Gait & Posture - Articles in Press

Discrimination of gender-, speed-, and shoe-dependent movement patterns in runners using full-body kinematics - Corrected Proof

2012-02-06

Highlights: ► Eigen value decomposition (PCA) introduced to full body kinematic analysis. ► Condition dependent characterization of human running movement. ► Changes of speed change first principal components, changes introduced by shoes can be found in higher principal components. ► PCA finds subject independent changes even when the changes introduced are small.Abstract: Changes in gait kinematics have often been analyzed using pattern recognition methods such as principal component analysis (PCA). It is usually just the first few principal components that are analyzed, because they describe the main variability within a dataset and thus represent the main movement patterns. However, while subtle changes in gait pattern (for instance, due to different footwear) may not change main movement patterns, they may affect movements represented by higher principal components.This study was designed to test two hypotheses: (1) speed and gender differences can be observed in the first principal components, and (2) small interventions such as changing footwear change the gait characteristics of higher principal components.Kinematic changes due to different running conditions (speed – 3.1m/s and 4.9m/s, gender, and footwear – control shoe and adidas MicroBounce shoe) were investigated by applying PCA and support vector machine (SVM) to a full-body reflective marker setup.Differences in speed changed the basic movement pattern, as was reflected by a change in the time-dependent coefficient derived from the first principal. Gender was differentiated by using the time-dependent coefficient derived from intermediate principal components. (Intermediate principal components are characterized by limb rotations of the thigh and shank.) Different shoe conditions were identified in higher principal components.This study showed that different interventions can be analyzed using a full-body kinematic approach. Within the well-defined vector space spanned by the data of all subjects, higher principal components should also be considered because these components show the differences that result from small interventions such as footwear changes.

Automated method to distinguish toe walking strides from normal strides in the gait of idiopathic toe walking children from heel accelerometry data - Corrected Proof

Gita Pendharkar, Paul Percival, David Morgan, Daniel Lai — 2012-02-02

Highlights: ► We embedded accelerometers in the heel of the boots and sampled heel motion data. ► A classifier to distinguish toe walking stride from normal stride was developed. ► The algorithm has an accuracy of 98.5% for subjects with similar gait frequency. ► The algorithm can be implemented in a microcontroller and made portable. ► The algorithm can be modified to assess toe walking in other gait disorders.Abstract: Toe walking mainly occurs in children due to medical condition or physical injury. When there are no obvious signs of any medical condition or physical injury, a diagnosis of Idiopathic Toe Walking (ITW) is made. ITW children habitually walk on their toes, however can modify their gait and walk with a heel–toe gait if they want to. Correct gait assessment in ITW children therefore becomes difficult. To solve this problem, we have developed an automated way to assess the gait in ITW children using a dual axis accelerometer. Heel acceleration data was recorded from the gait of ITW children using boots embedded with the sensor in the heel and interfaced to a handheld oscilloscope. An innovative signal processing algorithm was developed in IgorPro to distinguish toe walking stride from normal stride using the acceleration data. The algorithm had an accuracy of 98.5%. Based on the statistical analysis of the heel accelerometer data, it can be concluded that the foot angle during mid stance in ITW children tested, varied from 36° to 11.5° while as in normal children the foot stance angle is approximately zero. This algorithm was later implemented in a system (embedded in the heel) which was used remotely to differentiate toe walking stride from normal stride. Although the algorithm classifies toe walking stride from normal stride in ITW children, it can be generalized for other applications such as toe walking in Cerebral Palsy or Acquired Brain Injury subjects. The system can also be used to assess the gait for other applications such as Parkinson's disease by modifying the algorithm.

Gait symmetry and velocity differ in their relationship to age - Corrected Proof

Kara K. Patterson, Neelesh K. Nadkarni, Sandra E. Black, William E. McIlroy — 2012-02-02

Highlights: ► Gait velocity declines with age. ► Measures of swing time, stance time and step length symmetry are not significantly associated with age in healthy adults or stroke survivors. ► Therefore, gait symmetry ratios can inform about effects of disease on the control of gait without the confound of age.Abstract: Measurement of gait is essential for identifying underlying deficits contributing to gait dysfunction, guiding clinical decisions and measuring rehabilitation outcomes. Velocity is commonly used to measure gait, however, its interpretation in patient populations is complicated by the confound of age. Gait symmetry may be an additional and valuable measure since it may not feature the same age-related changes as velocity. The purpose of this study was to determine if gait symmetry is related to age.Methods: Spatiotemporal gait parameters were recorded for 172 individuals with stroke and 81 healthy adults walking across a pressure sensitive mat at their preferred speed. Swing time, stance time and step length symmetry ratios were calculated. The relationship of age to velocity and symmetry was examined using Pearson correlations.Results: There was a significant negative association between velocity and age in the healthy group (r=−0.57, p<0.01). There were no significant relationships between age and any of the three symmetry ratios for either the stroke or healthy groups.Conclusions: The main finding of the current study is that gait symmetry ratios are not significantly associated with age in either a healthy or a post-stroke group. Gait symmetry ratios may therefore, allow the clinician and the researcher to make judgments about the effects of disease (such as stroke) on the control of an individual's gait without the confound of age.

The influence of heel height on lower extremity kinematics and leg muscle activity during gait in young and middle-aged women - Corrected Proof

Anna Mika, Łukasz Oleksy, Piotr Mika, Anna Marchewka, Brian C. Clark — 2012-02-02

Highlights: ► In young and middle-aged women muscle activity and lower limbs kinematics were assessed during gait in heeled shoes. ► Footwear of the stiletto type increases the leg muscle activity and changes knee and ankle kinematics during gait. ► Permanent wearing of heeled footwear could contribute to muscle overuse and repetitive strain injuries. ► Age-related changes alter in certain body segments the biomechanical adjustments associated with wearing heeled shoes.Abstract: The aim of this study was to evaluate the changes in electromyographic (EMG) activity of the lower limb muscles, and hip, knee and ankle kinematics during gait while wearing low- (4-cm) and high-heeled (10-cm) shoes in 31 young and 15 middle-aged adult women.We observed an increase in knee flexion and decrease in ankle eversion associated with elevated heel heights suggesting that compensatory mechanisms attenuating ground reaction forces may be compromised during gait with higher-heeled shoes. Additionally, we observed increased muscle activity during high-heeled gait that may exacerbate muscle fatigue. Collectively, these findings suggest that permanent wearing of heeled footwear could contribute to muscle overuse and repetitive strain injuries.

Ambulatory measurement of the scapulohumeral rhythm: Intra- and inter-operator agreement of a protocol based on inertial and magnetic sensors - Corrected Proof

I. Parel, A.G. Cutti, G. Fiumana, G. Porcellini, G. Verni, A.P. Accardo — 2012-02-02

Highlights: ► We developed a motion analysis protocol named ISEO for the ambulatory measure of the scapulohumeral rhythm. ► We assessed ISEO intra and inter-operator agreement involving 2 operators and 40 subjects. ► We quantified the similarity of scapulohumeral patterns and the smallest detectable difference in scapula range of motion. ► The similarity was acceptable for most of the scapula rotations. ► The smallest detectable difference ranged from 4.4° to 8.6°.Abstract: To measure the scapulohumeral rhythm (SHR) in outpatient settings, the motion analysis protocol named ISEO (INAIL Shoulder and Elbow Outpatient protocol) was developed, based on inertial and magnetic sensors. To complete the sensor-to-segment calibration, ISEO requires the involvement of an operator for sensor placement and for positioning the patient's arm in a predefined posture. Since this can affect the measure, this study aimed at quantifying ISEO intra- and inter-operator agreement. Forty subjects were considered, together with two operators, A and B. Three measurement sessions were completed for each subject: two by A and one by B. In each session, the humerus and scapula rotations were measured during sagittal and scapular plane elevation movements. ISEO intra- and inter-operator agreement were assessed by computing, between sessions, the: (1) similarity of the scapulohumeral patterns through the Coefficient of Multiple Correlation (CMC2), both considering and excluding the difference of the initial value of the scapula rotations between two sessions (inter-session offset); (2) 95% Smallest Detectable Difference (SDD95) in scapula range of motion.Results for CMC2 showed that the intra- and inter-operator agreement is acceptable (median≥0.85, lower-whisker ≥0.75) for most of the scapula rotations, independently from the movement and the inter-session offset. The only exception is the agreement for scapula protraction–retraction and for scapula medio-lateral rotation during abduction (inter-operator), which is acceptable only if the inter-session offset is removed. SDD95 values ranged from 4.4° to 8.6° for the inter-operator and between 4.9° and 8.5° for the intra-operator agreement.In conclusion, ISEO presents a high intra- and inter-operator agreement, particularly with the scapula inter-session offset removed.

Swing limb mechanics and minimum toe clearance in people with knee osteoarthritis - Corrected Proof

2012-01-27

Abstract: Objective: Knee osteoarthritis (OA) has been shown to be a risk factor for falls. Reductions in foot clearance during the swing phase of walking can cause a trip and potentially lead to a fall. This study examined the swing phase mechanics of people with and without knee OA during walking.Design: Minimum toe clearance (MTC) height, joint angles at the time of MTC and the influence of the angular changes of the hip, knee and ankle of the swing leg on foot clearance using sensitivity analysis were investigated in 50 knee OA participants and 28 age-matched asymptomatic controls.Results: Although both groups had a similar MTC height (controls: 12.8±6.7mm, knee OA: 13.4±7.0mm), the knee OA group used a different strategy to achieve the same foot clearance, as evidenced by greater knee flexion (52.5±5.3° vs 49.4±4.8°, p=0.007), greater hip abduction (−3.6±3.3° vs −1.8±3.3°, p=0.03) and less ankle adduction (2.8±1.9° vs 4.2±2.1°, p=0.01).Conclusion: MTC height was comparable between the groups, however a different swing phase mechanism was used by the knee OA. Although adequate MTC is an important component of safe locomotion, it does not appear to be impaired in people with knee OA. Other factors, such as inadequate responses to postural perturbation, may be responsible for falls in this group.

Effects of age and pathology on stance modifications in response to increased postural threat - Corrected Proof

James A. Shaw, Leslie E. Stefanyk, James S. Frank, Mandar S. Jog, Allan L. Adkin — 2012-01-27

Highlights: ► Potential of a physical threat to stability elevated postural anxiety. ► Trunk sway changes in response to elevated anxiety depended on age. ► Anxiety increased sway in young adults but decreased sway in older adults. ► Trunk sway did not change in response to elevated anxiety in individuals with PD. ► This lack of adaptation should be considered when training balance and gait in PD.Abstract: This study investigated modifications to standing posture in response to elevated postural anxiety evoked by a potential physical threat to stability. Sixteen young adults, 16 older adults and 16 patients diagnosed with Parkinson's disease (PD) stood with or without the expectation of a threat to their posture (i.e., external trunk perturbation). This method allowed for the assessment of the effects of anticipatory anxiety on standing posture associated with an ecologically valid and direct threat to stability. Our manipulation was successful as all participants, independent of age and disease, reported significant increases in postural anxiety when anticipating a threat to their posture. The trunk sway modifications observed in response to elevated postural anxiety were dependent on age and disease. Young adults showed increased trunk sway in both pitch and roll directions while older adults demonstrated decreased trunk sway but only in the roll direction when standing and expecting a threat to posture compared to standing without this threat. Individuals with PD showed no significant changes in trunk pitch or roll sway when anticipating a threat to posture compared to standing without this threat. Our findings suggest that the effects of postural anxiety on postural control are dependent on the context associated with the postural threat, and age and disease status.

Body-worn motion sensors detect balance and gait deficits in people with multiple sclerosis who have normal walking speed - Corrected Proof

2012-01-25

Highlights: ► Stopwatch-timed mobility tests are insensitive to mild multiple sclerosis (MS). ► We compared timed mobility tests with instrumented body-worn sensors in the clinic. ► Stopwatch timed measures did not distinguish mild MS from control subjects. ► The sensors found significant differences in balance and gait parameters in MS. ► Body-worn sensors may prove a useful and practical MS mobility outcome measure.Abstract: While balance and gait limitations are hallmarks of multiple sclerosis (MS), standard stopwatch-timed measures practical for use in the clinic are insensitive in minimally affected patients. This prevents early detection and intervention for mobility problems. The study sought to determine if body-worn sensors could detect differences in balance and gait between people with MS with normal walking speeds and healthy controls. Thirty-one MS and twenty-eight age- and sex-matched control subjects were tested using body-worn sensors both during quiet stance and gait (Timed Up and Go test, TUG). Results were compared to stopwatch-timed measures. Stopwatch durations of the TUG and Timed 25 Foot Walk tests were not significantly different between groups. However, during quiet stance with eyes closed, people with MS had significantly greater sway acceleration amplitude than controls (p=0.02). During gait, people with MS had greater trunk angular range of motion in roll (medio-lateral flexion, p=0.017) and yaw (axial rotation, p=0.026) planes. Turning duration through 180° was also longer in MS (p=0.031). Thus, body-worn motion sensors detected mobility differences between MS and healthy controls when traditional timed tests could not. This portable technology provides objective and quantitative mobility data previously not obtainable in the clinic, and may prove a useful outcome measure for early mobility changes in MS.

Relation between risk of falling and postural sway complexity in diabetes - Corrected Proof

S. Morrison, S.R. Colberg, H.K. Parson, A.I. Vinik — 2012-01-24

Highlights: ► Older individuals with type 2 diabetes are at a high risk of falling than healthy people of a similar age. ► Persons at high risk of falling exhibited changes in postural motion compared to low-risk, healthy adults. ► Balance training resulted in a decline in falls risk for all older persons. ► With training, the postural motion of the older person with type 2 diabetes became more similar to the healthy adult.Abstract: For older individuals with diabetes, any decline in balance control can be especially problematic since it is often a precursor to an increased risk of falling. This study was designed to evaluate differences in postural motion dynamics and falls risk for older individuals with type 2 diabetes (T2DM) classified as fallers/non-fallers and, to assess what impact exercise has on balance and falls risk. The results demonstrated that the risk of falling is greater for those older individuals with multiple risk factors including diabetes and a previous falls history. The postural motion features of the high-risk individuals (T2DM-fallers) were also different, being characterized by increased variability and complexity, increased AP-ML coupling, less overall COP motion and increased velocity. One suggestion is that these individuals evoked a stiffening strategy during the more challenging postural tasks. Following training, a decline in falls risk was observed for all groups, with this effect being most pronounced for the T2DM-fallers. Interestingly, the COP motion of this group became more similar to controls, exhibiting decreased complexity and variability, and decreased velocity. The reciprocal changes in COP complexity support the broader view that age/disease-related changes in physiological complexity are bi-directional. Overall, these results show that, even for older T2DM individuals at greater risk of falling, targeted interventions can positively enhance their postural dynamics. Further, the finding that the pattern of postural motion variability and complexity was altered highlights that a decline in physiological complexity may not always be negatively associated with aging and/or disease

Progressive resistance training improves gait initiation in individuals with Parkinson's disease - Corrected Proof

Chris J. Hass, Thomas A. Buckley, Chris Pitsikoulis, Ernest J. Barthelemy — 2012-01-24

Highlights: ► Strength training (ST) may improve postural control in Parkinson's disease patients. ► Studied a 10-week ST program and biomechanical analysis of gait initiation (GI). ► ST subjects improved GI anticipatory postural adjustments and stride performance. ► ST subjects increased strength and safely completed the 10 week program.Abstract: An impaired ability to initiate walking is a common feature of postural instability and gait impairment in Parkinson's disease. While progressive resistance training (PRT) has been proposed to be an effective modality to improve balance and gait function in people with Parkinson's disease, there are a limited number of randomized trials and no studies have evaluated gait initiation performance. Thus, the purpose of this study was to examine the potential benefits PRT on GI performance in people with Parkinson's disease. Eighteen individuals with idiopathic PD were randomly assigned to either a twice weekly PRT program or a non-contact control group for 10 weeks. Biomechanical analysis of GI was performed pre- and post-intervention. Dependent variables of interest included the displacement of the center-of-pressure (COP) during the anticipatory postural phase of GI as well as the initial stride length and velocity. The PRT group demonstrated improvements in the posterior displacement of the COP and the initial stride length and velocity. There were no improvements in any variables for the control subjects. These results suggest that PRT may be an effective non-pharmacological and nonsurgical treatment to improve GI performance in PWP.

Planar covariation of elevation angles in prosthetic gait - Corrected Proof

F. Leurs, A. Bengoetxea, A.M. Cebolla, C. De Saedeleer, B. Dan, G. Cheron — 2012-01-18

Highlights: ► Kinematic strategies in transfemoral amputees were analyzed by planar covariation. ► The typical elliptic loop was preserved in prosthetic walking in both limbs. ► The orientation of the loop for the prosthetic limb did not change with speed. ► The relation to speed was even stronger for the sound limb than for control subjects. ► These results reveal a centrally commanded compensation strategy.Abstract: In order to achieve efficacious walking, transfemoral amputees must adapt coordination within both the artificial and the sound lower limb. We analyzed kinematic strategies in amputees using the planar covariation of lower limb segments approach. When the elevation angles of the thigh, shank and foot are plotted one versus the others, they describe a regular loop which lies close to a plane in normal adults’ gait. Orientation of this plane changes with increased speed, in relation to mechanical energetic saving. We used an opto-electronic device to record the elevation angles of both limbs’ segments of novice and expert transfemoral amputees and compared them to those of control subjects. The statistical structure underlying the distribution of these angles was described by principal component analysis and Fourier transform. The typical elliptic loop was preserved in prosthetic walking, in both limbs in both novice and expert transfemoral amputees. This reflects a specific control over the thigh elevation angle taking into account knowledge of the other elevation angles throughout the gait cycle. The best-fitting plane of faster trials rotates around the long axis of the gait loop with respect to the plane of slower trials for control subjects, and even more for the sound limb of expert amputees. In contrast, plane rotation is very weak or absent for the prosthetic limb. We suggest that these results reveal a centrally commanded compensation strategy.

Sensitivity of the OLGA and VCM models to erroneous marker placement: Effects on 3D-gait kinematics - Corrected Proof

B.E. Groen, M. Geurts, B. Nienhuis, J. Duysens — 2012-01-16

Highlights: ► We evaluated the sensitivity of the OLGA and VCM model to marker displacements. ► Errors due to marker displacement were generally larger than step-to-step variations. ► 3D gait kinematics were most sensitive to shank, knee and thigh marker displacements. ► OLGA was less sensitive to marker displacements. ► Accurate marker placements remains crucial for adequate 3D gait analysis.Abstract: Gait data need to be reliable to be valuable for clinical decision-making. To reduce the impact of marker placement errors, the Optimized Lower Limb Gait Analysis (OLGA) model was developed. The purpose of this study was to assess the sensitivity of the kinematic gait data to a standard marker displacement of the OLGA model compared with the standard Vicon Clinical Manager (VCM) model and to determine whether OLGA reduces the errors due to the most critical marker displacements. Healthy adults performed six gait sessions. The first session was a standard gait session. For the following sessions, 10mm marker displacements were applied. Kinematic data were collected for both models. The root mean squares of the differences (RMS) were calculated for the kinematics of the displacement sessions with respect to the first session. The results showed that the RMS values were generally larger than the stride-to-stride variation except for the pelvic kinematics. For the ankle, knee and hip kinematics, OLGA significantly reduced the averaged RMS values for most planes. The shank, knee and thigh anterior–posterior marker displacements resulted in RMS values exceeding 10°. OLGA reduced the errors due to the knee and thigh marker displacements, but not the errors due to the ankle marker displacements. In conclusion, OLGA reduces the effect of erroneous marker placement, but does not fully compensate all effects, indicating that accurate marker placement remains of crucial importance for adequate 3D-gait analysis and subsequent clinical decision-making.

Gait and menstrual cycle: Ovulating women use sexier gaits and walk slowly ahead of men - Corrected Proof

Nicolas Guéguen — 2012-01-16

Highlights: ► Gait and women’ walking were examined according to their menstrual cycle. ► The amount of time that women spent walking ahead a male was measured. ► The sexiness of their gaits recorded with the help of a spy-camera was evaluated by males. ► Ovulation phase was measured with an LH salivary test. ► Near ovulation, women walked slower and their gait was subjectively rated as sexier.Abstract: Previous research has demonstrated that women's physical appearance or sexual interest is different across the menstrual cycle. However, the nonverbal behavior of women toward men according to their menstrual cycle has not been previously explored. In this study, the gait of women walking ahead a male confederate was recorded with the help of a spy-camera. The amount of time that women spent walking was the first dependent variable whereas the extent to which the women were perceived to be sexually attractive by two judges was the second dependent variable. Comparisons were performed according to the women's ovulation phase measured with an LH salivary test. Near ovulation, it was found that women walked slower and their gait was subjectively rated as sexier. Such behaviors were interpreted as unconscious desires of women near ovulation to reinforce their attractiveness in order to attract more men and to increase their choice of a partner.

Enhanced somatosensory information decreases postural sway in older people - Corrected Proof

2012-01-16

Highlights: ► We examined the effects of textured insole surfaces on changing postural sway of young and older people during standing. ► We tested people under conditions of vision, no vision, firm and foam surfaces. ► The textured insole surface decreased postural sway in older people especially while standing on a foam surface with no vision. ► Changes in postural sway were attributed due to the enhancement of the somatosensory information received from the feet.Abstract: The somatosensory system plays an important role in balance control and age-related declines in somatosensory function have been implicated in falls incidence. Different types of insole devices have been developed to enhance somatosensory information and improve postural stability. However, they are often too complex and expensive to integrate into daily life and textured insole surfaces may provide an inexpensive and accessible means to enhance somatosensory input. This study investigated the effects of textured insole surfaces on postural sway in ten younger and seven older participants performing standing balance tests on a force plate under three insole surface conditions: (1) barefoot; (2) with hard; and (3), soft textured insole surfaces. With each insole surface, participants were tested under two vision conditions (eyes open, closed) on two standing surfaces (firm, foam). Four 30s trials were collected for different combinations of insole surface, standing surface and vision. Centre of pressure measurements included the range and standard deviation of anterior–posterior and medial–lateral displacement, path length and the 90% confidence elliptical area. Results revealed a significant Group*Surface*Insole interaction for five of the dependent variables. Compared to younger individuals, postural sway was greater in older people on both standing surfaces in the barefoot condition. However, both textured insole surfaces reduced postural sway for the older group especially in the eyes closed condition on a foam surface. These findings suggest that textured insole surfaces can reduce postural sway in older people, particularly during more challenging balance tasks. Textured insole surfaces may afford a low-cost means of decreasing postural sway, providing an important intervention in falls prevention.

Computerized gait analysis in Legg–Calvé–Perthes disease—Analysis of the sagittal plane - Corrected Proof

B. Westhoff, F. Martiny, A. Reith, R. Willers, R. Krauspe — 2012-01-13

Highlights: ► In florid stage significantly impaired sagittal plane kinematics on involved and non-involved side. ► Significantly reduced power generation and absorption mainly at the level of involved hip. ► In final stage impaired global hip function in 46, 2% of patients.Abstract: Current follow-up- and outcome-evaluations of Legg–Calvé–Perthes disease (LCPD) are based on subjective measures of function, clinical and radiological parameters. The objective of this study was to evaluate the sagittal plane kinematics and the effect on hip joint loading on the affected hip in children with LCPD.Materials and methods: Computerized gait analysis was performed in 49 LCPD patients aged ≥5 years with unilateral hip involvement. Sagittal plane kinematics and kinetics were compared to a group of healthy children (n=30).Results: Kinematics: a significantly increased anterior tilt and range of motion (ROM) of the pelvis combined with a marked reduction of the extension of the involved hip joint compared to the control group was observed. The increased ROM of the contralateral hip results from increased maximum flexion. Power generation: overall significantly decreased on the involved side during florid stage. Global hip function: significantly reduced hip flexor index of the involved hip; 46.2% of the patients in advanced stage, although having no significant changes in kinematics – except increased anterior pelvic tilt – had a pathologic HFI.Conclusion: Sagittal plane hip function is significantly impaired in florid and advanced LCPD. The results of this study will lead to further investigations into whether this development can be prevented by conservative or operative treatment thus improving function and long-term prognosis.

Online control of anticipated postural adjustments in step initiation: Evidence from behavioral and computational approaches - Corrected Proof

L. Mouchnino, G. Robert, H. Ruget, J. Blouin, M. Simoneau — 2012-01-13

Highlights: ► Online control of the anticipatory postural adjustments (APAs) during gait initiation was investigated. ► APAs were modified online when a body perturbation occurred during their execution. ► Changes in the APAs were triggered when a mismatch between passively originated forces and those actively specified by the central command was detected.Abstract: Anticipatory postural adjustments (APAs) prior to step execution are thought to be immutable once released. Here we challenge this assumption by testing whether APAs can be modified online if a body perturbation occurs during execution. Two directions of perturbation (resisting and assisting) relative to the body weight transfer were used during the execution of APAs. We found that APAs are modified online (increase in both ground pressure and muscle activity) to compensate for resisting perturbations. The outcomes of a biomechanical model confirmed that the early changes in the APAs resulted from an active control of the APAs and were not merely mechanical consequences of the perturbation. However, no modification of the initial feedforward command was observed for assisting perturbations. The motor command changes for the resisting perturbation may originate from the mismatch between passively originated forces and those actively specified by the central command when acting in the opposite direction. The absence of a mismatch in the assisting perturbation might explain why the central nervous system was not prompted to modify the APAs in this condition.

Kinematic and kinetic characteristics of Masai Barefoot Technology footwear - Corrected Proof

Masashi Taniguchi, Hiroshige Tateuchi, Toru Takeoka, Noriaki Ichihashi — 2012-01-12

Highlights: ► We examined the immediate effects of using Masai Barefoot Technology (MBT) footwear in the lower extremity in healthy males. ► MBT shoes could assist with shock absorption and maintain the progression force. ► MBT shoes might be effective to improve shock absorption and assist ankle push-off.Abstract: The Masai Barefoot Technology (MBT) shoe was developed as a walking device to improve gait stability and reduce the joint load. Kinematic changes with MBT shoes have been reported; however, kinetic characteristics with MBT shoes have not been adequately assessed. The purpose of this study was to investigate the immediate effects of using MBT footwear on the kinetic and kinematic changes in the lower extremity in healthy males. Fourteen healthy male subjects (mean age: 25.6±5.1 years) underwent three-dimensional gait analysis. Ground reaction forces (GRF) during the shock absorption phase were significantly decreased with MBT shoes compared with stable shoes. Gait with the MBT shoes showed significantly decreased knee extension angle in the early stance phase, a decreased hip extension angle, and an increased ankle dorsiflexion angle in the late stance phase. The peak value of the ankle planter moment, ankle negative power, and vertical component of the GRF significantly decreased with MBT shoes in the late stance phase compared with stable shoes. Therefore, MBT shoes could assist with shock absorption in the early stance phase and maintain the progression force while reducing joint moment and power. The results of this study suggest that MBT shoes might be effective to improve shock absorption, increase knee extensor muscle activity, and assist ankle push-off.

Compensatory balance reactions during forward and backward walking on a treadmill - Corrected Proof

D.A.E. Bolton, J.E. Misiaszek — 2012-01-09

Highlights: ► Balance perturbations that oppose the direction of walking are expected to yield larger amplitude corrective reactions. ► We compared corrective balance reactions during forward and backward treadmill walking. ► Backwards perturbations resulted in the largest amplitude reactions, regardless of walking direction.Abstract: Previous work suggests that balance perturbations to the body opposing the direction of progression during walking lead to larger amplitude corrective reactions than perturbations concurrent with walking direction. To test this hypothesis, subjects received forward and backward perturbations applied to the pelvis through a padded harness, while walking forwards or backwards on a treadmill. Contrary to our hypothesis, the greatest responses were associated with backward perturbations regardless of the direction of walking.

Cell phones change the way we walk - Corrected Proof

Eric M. Lamberg, Lisa M. Muratori — 2012-01-09

Highlights: ► While walking and using a cell phone is common, effects on gait are unclear. ► We investigated if walking errors occur when talking or texting on a cell phone. ► Gait velocity is reduced when using a cell phone while talking or texting. ► Navigational errors occur when texting while walking. ► Texting while walking produces greater interference than talking on a cell phone.Abstract: Cell phone use among pedestrians leads to increased cognitive distraction, reduced situation awareness and increases in unsafe behavior. Performing a dual-task, such as talking or texting with a cell phone while walking, may interfere with working memory and result in walking errors. At baseline, thirty-three participants visually located a target 8m ahead; then vision was occluded and they were instructed to walk to the remembered target. One week later participants were assigned to either walk, walk while talking on a cell phone, or walk while texting on a cell phone toward the target with vision occluded. Duration and final location of the heel were noted. Linear distance traveled, lateral angular deviation from the start line, and gait velocity were derived. Changes from baseline to testing were analyzed with paired t-tests. Participants engaged in cell phone use presented with significant reductions in gait velocity (texting: 33% reduction, p=0.01; talking: 16% reduction, p=0.02). Moreover, participants who were texting while walking demonstrated a 61% increase in lateral deviation (p=0.04) and 13% increase in linear distance traveled (p=0.03). These results suggest that the dual-task of walking while using a cell phone impacts executive function and working memory and influences gait to such a degree that it may compromise safety. Importantly, comparison of the two cell phone conditions demonstrates texting creates a significantly greater interference effect on walking than talking on a cell phone.

The effects of word length, articulation, oral-motor movement, and lexicality on gait: A pilot study - Corrected Proof

2012-01-09

Highlights: ► It is possible to deconstruct a verbal task to examine motoric, articulatory, and lexical demands. ► Gait seems to be most affected by the motoric demands of speaking. ► Articulatory and lexical demands may not produce incremental changes in gait over the motoric demands of speaking.Abstract: Previous research has suggested that articulatory demands are important predictors of the impact of dual-task interference on spatial-temporal parameters of gait. In this study, we evaluated the effects of word length, oral-motor movement, articulation, and lexicality, within a verbal task, on a continuous gait task. Fifteen healthy young women participated in a study in which two word lengths (monosyllabic and bisyllabic) were crossed with four levels of secondary task complexity (no dual-task, non-speech movement, spoken non-word, and spoken word). Spatial and temporal parameters of gait were measured using a 23′ instrumented carpet. Results indicated a significant multivariate main effect for task type, F(15, 120)=3.07, that explained 71.1% of the demonstrated variability in gait. Univariate analyses of this main effect revealed statistically significant effects for velocity, step time, swing time, and stance time, but no statistically significant effect for step length. Post hoc analyses suggested that dual-task interference produced significant changes in the parameters of gait, but that this interference was not significantly greater with non-words as compared to the non-speech movement condition, nor was it significantly greater with words as compared to non-words. The results of this systematic deconstruction of a simple verbal task suggest that the motor component of a secondary speech task may produce the largest amount of interference within a dual-task interference paradigm.

A linear soft tissue artefact model for human movement analysis: Proof of concept using in vivo data - Corrected Proof

2012-01-09

Highlights: ► We linearly modelled soft tissue artefact (STA) for walking, cutting and hopping. ► The linear model parameters were computed from bone pin data using PCA. ► Modelling errors were reduced from cm to mm scale compared to a rigid-body model. ► 95% of the STA variance are captured with a five degrees-of-freedom linear model. ► STA is dominated by rigid-body motions rather than deformations.Abstract: We investigated the accuracy of a linear soft tissue artefact (STA) model in human movement analysis. Simultaneously recorded bone-mounted pin and skin marker data for the thigh and shank during walking, cutting and hopping were used to measure and model the motion of the skin marker clusters within anatomical reference frames (ARFs). This linear model allows skin marker movements relative to the underlying bone contrary to a rigid-body assumption. The linear model parameters were computed through a principal component analysis, which revealed that 95% of the variance of the STA motion for the thigh was contained in the first four principal components for all three tasks and all subjects. For the shank, 95% of the variance was contained in the first four principal components during walking and cutting and first five during hopping. For the thigh, the maximum residual artefact was reduced from 27.0mm to 5.1mm (walking), 22.7mm to 3.0mm (cutting) and 16.2mm to 3.5mm (hopping) compared to a rigid-body assumption. Similar reductions were observed for the shank: 24.2mm to 1.9mm (walking), 20.3mm to 1.9mm (cutting) and 14.7mm to 1.8mm (hopping). A geometric analysis of the first four principal components revealed that, within the ARFs, marker cluster STA is governed by rigid-body translations and rotations rather than deformations. The challenge remains, however, in finding the linear model parameters without bone pin data, but this investigation shows that relatively few parameters in a linear model are required to model the vast majority of the STA movements.

The minimal clinically important difference for the Gait Profile Score - Corrected Proof

2012-01-09

Highlights: ► A minimally clinically important difference is derived for the Gait Profile Score. ► Based on variability of typically developing children. ► Based on difference between Functional Assessment Questionnaire levels. ► MCID is 1.6°.Abstract: The minimally clinically important difference (MCID) is an important concept for interpreting the results of clinical research. This paper proposes a rationale for defining an MCID for the Gait Profile Score (GPS) based on an analysis of the difference in median GPS for children classified at different levels of the Functional Assessment Questionnaire. A strong linear correlation between median score and FAQ level was found. An MCID of 1.6° is therefore suggested, reflecting the mean difference between adjacent FAQ levels. Comparison of this value with (i) the standard deviation of GPS from typically developing children (1.4°) and (ii) the percentage of the difference between the median GPS for each FAQ level and that for typically developing children offers further support to suggest that 1.6° is an appropriate figure.

Direction specific preserved limits of stability in early progressive supranuclear palsy: A dynamic posturographic study - Corrected Proof

Mohan Ganesan, Shaik Afsar Pasha, Pramod Kumar Pal, Ravi Yadav, Anupam Gupta — 2012-01-09

Highlights: ► Patients with PSP had impaired dynamic balance indices compared to controls. ► The overall limits of stability (LOS) was decreased in PSP compared to controls. ► In early PSP, the LOS was preserved in the left and forward-left directions. ► Evidence of lateralization for balance and postural control in normal subjects.Abstract: Objectives: To quantitatively detect the nature of balance impairment in patients with progressive supranuclear palsy (PSP) using dynamic posturography.Methods: Twenty clinically diagnosed PSP patients (8 women, 12 men; age: 62.1±7.7 years; duration: 2.6±1.3 years) and 20 healthy controls were studied. All subjects were right side dominant. They were evaluated by dynamic posturography (Biodex, USA). The measurements included (i) balance indices: ability to control balance in all directions (overall balance index, OBI), front to back (anterior–posterior index, API) and side-to-side (medio-lateral index, MLI), and (ii) the limits of stability (LOS) in 8 directions: forward (FW), backward (BW), right (RT), left (LT), forward-right (FW-RT), forward-left (FW-LT), backward-right (BW-RT) and backward-left (BW-LT).Results: Compared to controls, patients showed significantly higher OBI (p<0.001), API (p=0.003) and MLI (p<0.001), implying impaired balance. The total LOS score was significantly lower (implying poor stability) in PSP than in controls (18.3±7.3 vs. 28.4±8.5, p<0.001). Patients took significantly longer time to complete LOS test (262.7±33.0s vs. 135.4±20.6s, p<0.001). Direction-wise analysis showed that PSP patients had significantly lower LOS scores in FW, BW, RT, FW-RT, BW-RT and BW-LT directions compared to controls. However the scores in LT and FW-LT did not differ significantly.Conclusions: PSP patients showed impaired balance indices and decreased overall LOS compared to controls. Though LOS is affected in PSP, the scores in the left (non-dominant side) and forward-left (non-dominant forward diagonal) directions were preserved.

Evaluation of robot-assisted gait training using integrated biofeedback in neurologic disorders - Corrected Proof

Oliver Stoller, Marco Waser, Lukas Stammler, Corina Schuster — 2012-01-03

Highlights: ► This biofeedback approach cannot detect progress during robot-assisted gait training (RAGT). ► Hip flexion activity decreased following 8 RAGT sessions. ► Knee extension activity increased following 8 RAGT sessions. ► Consider these findings when refining existing or developing new biofeedback strategies for RAGT.Abstract: Background: Neurological disorders lead to walking disabilities, which are often treated using robot-assisted gait training (RAGT) devices such as the driven gait-orthosis Lokomat. A novel integrated biofeedback system was developed to facilitate therapeutically desirable activities during walking. The aim of this study was to evaluate the feasibility to detect changes during RAGT by using this novel biofeedback approach in a clinical setting for patients with central neurological disorders.Methods: 84 subjects (50 men and 34 women, mean age of 58±13years) were followed over 8 RAGT sessions. Outcome measures were biofeedback values as weighted averages of torques measured in the joint drives and independent parameters such as guidance force, walking speed, patient coefficient, session duration, time between sessions and total treatment time.Results: Joint segmented analysis showed significant trends for decreasing hip flexion activity (p≤.003) and increasing knee extension activity (p≤.001) during RAGT sessions with an intercorrelation of r=−.43 (p≤.001). Further associations among independent variables were not statistically significant.Conclusion: This is the first study that evaluates the Lokomat integrated biofeedback system in different neurological disorders in a clinical setting. Results suggest that this novel biofeedback approach used in this study is not able to detect progress during RAGT. These findings should be taken into account when refining existing or developing new biofeedback strategies in RAGT relating to appropriate systems to evaluate progress and support therapist feedback in clinical settings.

Motor learning benefits of self-controlled practice in persons with Parkinson's disease - Corrected Proof

Suzete Chiviacowsky, Gabriele Wulf, Rebecca Lewthwaite, Tiago Campos — 2012-01-03

Highlights: ► Persons with Parkinson's disease practice a balance task (stabilometer). ► We compare learning in groups with and without self-controlled use of a balance pole. ► Self-controlled use of the pole enhances learning compared with no self-control. ► Self-controlled practice increases motivation and reduces nervousness. ► Satisfying people's need for autonomy promotes learning.Abstract: The present study examined the effectiveness of a training method to enhance balance in people with PD, which could potentially reduce their risk for falls. Specifically, we investigated whether the benefits of the self-controlled use of a physical assistance device for the learning of a balance task, found previously in healthy adults, would generalize to adults with PD. Twenty-eight individuals with PD were randomly assigned to one of two groups, a self-control and a yoked (control) group. The task required participants to stand on a balance platform (stabilometer), trying to keep the platform as close to horizontal as possible during each 30-s trial. In the self-control group, participants had a choice, on each of 10 practice trials, to use or not to use a balance pole. Participants in the yoked group received the same balance pole on the schedule used by their counterparts in the self-control group, but did not have a choice. Learning was assessed one day later by a retention test. The self-control group demonstrated more effective learning of the task than the yoked group. Questionnaire results indicated that self-control participants were more motivated to learn the task, were less nervous, and less concerned about their body movements relative to yoked participants. Possible reasons for the learning benefits of self-controlled practice, including a basic psychological need for autonomy, are discussed.

Study II: Mechanoreceptive sensation is of increased importance for human postural control under alcohol intoxication - Corrected Proof

F. Modig, M. Patel, M. Magnusson, P.A. Fransson — 2011-12-29

Highlights: ► The recorded stability during alcohol intoxication is significantly influenced by individual mechanoreceptive sensation. ► The relationship between stability and mechanoreceptive sensation is changed by intoxication level, vision and adaptation. ► Plantar mechanoreceptive sensation becomes more important for postural control when more heavily intoxicated. ► The influence of alcohol on postural stability and adaptation is strongly dependent on efficient sensory re-weighting.Abstract: Standing postural stability relies on input from visual, vestibular, proprioceptive and mechanoreceptive sensors. When the information from any of these sensors is unavailable or disrupted, the central nervous system maintains postural stability by relying more on the contribution from the reliable sensors, termed sensory re-weighting. Alcohol intoxication is known to affect the integrity of the vestibular and visual systems. The aim was to assess how mechanoreceptive sensory information contributed to postural stability at 0.00% (i.e. sober), 0.06% and 0.10% blood alcohol concentration (BAC) in 25 healthy subjects (mean age 25.1 years). The subjects were assessed with eyes closed and eyes open under quiet standing and while standing was perturbed by repeated, random-length, vibratory stimulation of the calf muscles. Plantar cutaneous mechanoreceptive sensation was assessed for both receptor types: slowly adapting (tactile sensitivity) and rapidly adapting (vibration perception). The correlation between recorded torque variance and the sensation from both mechanoreceptor types was calculated.The recorded stability during alcohol intoxication was significantly influenced by both the tactile sensation and vibration perception of the subjects. Moreover, the study revealed a fluctuating association between the subjects’ vibration perception and torque variance during balance perturbations, which was significantly influenced by the level of alcohol intoxication, vision and adaptation. Hence, one's ability to handle balance perturbations under the influence of alcohol is strongly dependent on accurate mechanoreceptive sensation and efficient sensory re-weighting.

Compressive tibiofemoral force during crouch gait - Corrected Proof

Katherine M. Steele, Matthew S. DeMers, Michael H. Schwartz, Scott L. Delp — 2011-12-29

Abstract: Crouch gait, a common walking pattern in individuals with cerebral palsy, is characterized by excessive flexion of the hip and knee. Many subjects with crouch gait experience knee pain, perhaps because of elevated muscle forces and joint loading. The goal of this study was to examine how muscle forces and compressive tibiofemoral force change with the increasing knee flexion associated with crouch gait. Muscle forces and tibiofemoral force were estimated for three unimpaired children and nine children with cerebral palsy who walked with varying degrees of knee flexion. We scaled a generic musculoskeletal model to each subject and used the model to estimate muscle forces and compressive tibiofemoral forces during walking. Mild crouch gait (minimum knee flexion 20–35°) produced a peak compressive tibiofemoral force similar to unimpaired walking; however, severe crouch gait (minimum knee flexion>50°) increased the peak force to greater than 6 times body-weight, more than double the load experienced during unimpaired gait. This increase in compressive tibiofemoral force was primarily due to increases in quadriceps force during crouch gait, which increased quadratically with average stance phase knee flexion (i.e., crouch severity). Increased quadriceps force contributes to larger tibiofemoral and patellofemoral loading which may contribute to knee pain in individuals with crouch gait.

Vision and agility training in community dwelling older adults: Incorporating visual training into programs for fall prevention - Corrected Proof

Rebecca J. Reed-Jones, Sandor Dorgo, Maija K. Hitchings, Julia O. Bader — 2011-12-29

Highlights: ► We examined the effects of visual training on mobility of older adults. ► A 12 week exercise intervention with visual training was used. ► The Nintendo Wii® was used as the tool for visual training. ► Visual training group significantly reduced collisions with obstacles. ► Visual training may be an important aspect for fall prevention programs.Abstract: This study aimed to examine the effect of visual training on obstacle course performance of independent community dwelling older adults. Agility is the ability to rapidly alter ongoing motor patterns, an important aspect of mobility which is required in obstacle avoidance. However, visual information is also a critical factor in successful obstacle avoidance. We compared obstacle course performance of a group that trained in visually driven body movements and agility drills, to a group that trained only in agility drills. We also included a control group that followed the American College of Sports Medicine exercise recommendations for older adults. Significant gains in fitness, mobility and power were observed across all training groups. Obstacle course performance results revealed that visual training had the greatest improvement on obstacle course performance (22%) following a 12 week training program. These results suggest that visual training may be an important consideration for fall prevention programs.

Comparison of plantar pressure distribution in adolescent runners at low vs. high running velocity - Corrected Proof

2011-12-28

Highlights: ► The impact of running velocity on foot plantar patterns distribution has not been explored in adolescent distance runners. ► Relative loads under the medial and central forefoot regions are higher while jogging compared to running. ► Relative loads under the lesser toes are higher while running compared to jogging. ► In order to prevent overloading of the metatarsals in young runners, excessive mileage at jogging pace should be avoided. ► Strengthening exercises of the foot musculature are recommended for protecting the first three metatarsals from overload.Abstract: This study aimed to compare foot plantar pressure distribution while jogging and running in highly trained adolescent runners. Eleven participants performed two constant-velocity running trials either at jogging (11.2±0.9km/h) or running (17.8±1.4km/h) pace on a treadmill. Contact area (CA in cm2), maximum force (Fmax in N), peak pressure (PP in kPa), contact time (CT in ms), and relative load (force time integral in each individual region divided by the force time integral for the total plantar foot surface, in %) were measured in nine regions of the right foot using an in-shoe plantar pressure device. Under the whole foot, CA, Fmax and PP were lower in jogging than in running (−1.2% [p<0.05], −12.3% [p<0.001] and −15.1% [p<0.01] respectively) whereas CT was higher (+20.1%; p<0.001). Interestingly, we found an increase in relative load under the medial and central forefoot regions while jogging (+6.7% and +3.7%, respectively; [p<0.05]), while the relative load under the lesser toes (−8.4%; p<0.05) was reduced. In order to prevent overloading of the metatarsals in adolescent runners, excessive mileage at jogging pace should be avoided.

The body configuration at step contact critically determines the successfulness of balance recovery in response to large backward perturbations - Corrected Proof

Vivian Weerdesteyn, Andrew C. Laing, Stephen N. Robinovitch — 2011-12-26

Highlights: ► We aimed to validate a biomechanical model for balance recovery in the backward direction. ► Ten young participants were exposed to very large backward balance perturbations. ► Primary outcome: successful recovery or fall. ► The variables from the model (leg and trunk angle at step contact) accurately predicted recovery outcome (95% correct). ► The model was more predictive than spatiotemporal step variables.Abstract: The mechanical efficiency of stepping to recover balance can be expressed by a biomechanical model that includes the trunk inclination angle and the angle of the leg at the instant of stepping-foot contact. The aim of the present study was to test the hypothesis that this model would accurately predict the successfulness of recovery attempts (recovery vs. falls) following large backward perturbations. Ten young participants were exposed to a series of 12 very large postural perturbations in the backward direction by means of a support-surface translation. At the instant of stepping-foot contact, we calculated the trunk inclination angle and the angle of the stepping leg with the vertical. Reaction time, step duration, step velocity and step length were also determined. A logistic regression analysis revealed that the model with leg and trunk inclination angles accurately predicted successful recovery, with a more forward tilted trunk and a further backward positioned leg increasing the probability of success. The set of spatiotemporal step variables was significantly less predictive. Over the course of the experiment, participants gradually became more successful in recovering balance, which coincided with an increase in leg but not in trunk angles. In conclusion, the body configuration at the instant of first stepping-foot contact accurately predicted successful balance recovery after a backward postural perturbation. Given the observation that participants improved their performance by increasing their leg angles, which suggests that it may be easier to improve this variable, compared to the trunk angle, by exercise interventions.

Study I: Effects of 0.06% and 0.10% blood alcohol concentration on human postural control - Corrected Proof

F. Modig, M. Patel, M. Magnusson, P.A. Fransson — 2011-12-26

Highlights: ► Between 0.06% and 0.10% BAC, a relatively small increase in BAC resulted in an abrupt decrease in postural control. ► Sustained exposure to repeated balance perturbations augments the alcohol-related destabilization. ► Alcohol intoxication causes larger destabilization in lateral direction than in anteroposterior direction. ► Alcohol intoxication decreases the adaptation capacity, especially for stability control in lateral direction.Abstract: Alcohol intoxication causes many accidental falls presented at emergency departments, with the injury severity often related to level of blood alcohol concentration (BAC). One way to evaluate the decline in postural control and the fall risk is to assess standing stability when challenged. The study objective was to comprehensively investigate alcohol-related impairments on postural control and adaptive motor learning at specific BAC levels.Effects of alcohol intoxication at 0.06% and 0.10% BAC were examined with posturography when unperturbed or perturbed by calf vibration. Twenty-five participants (mean age 25.1years) were investigated standing with either eyes open or closed.Our results revealed several significant findings: (1) stability declined much faster from alcohol intoxication between 0.06% and 0.10% BAC (60–140%) compared with between 0.0% and 0.06% BAC (30%); (2) sustained exposure to repeated balance perturbations augmented the alcohol-related destabilization; (3) there were stronger effects of alcohol intoxication on stability in lateral direction than in anteroposterior direction; and (4) there was a gradual degradation of postural control particularly in lateral direction when the balance perturbations were repeated at 0.06% and 0.10% BAC, indicating adaptation deficits when intoxicated.To summarize, alcohol has profound deteriorating effects on human postural control, which are dose dependent, time dependent and direction specific. The maximal effects of alcohol intoxication on physiological performance might not be evident initially, but may be revealed first when under sustained sensory-motor challenges.

Analysis of a kinetic multi-segment foot model part II: Kinetics and clinical implications - Corrected Proof

Dustin A. Bruening, Kevin M. Cooney, Frank L. Buczek — 2011-12-26

Highlights: ► The addition of kinetics may help diagnose some foot and ankle disorders. ► We have provided normative multi-segment foot joint moments and powers. ► Kinetics can be incorporated into other multi-segment foot models during push off. ► Power transfer occurs between the 1st metatarsophalangeal and mid-tarsal joints.Abstract: Kinematic multi-segment foot models have seen increased use in clinical and research settings, but the addition of kinetics has been limited and hampered by measurement limitations and modeling assumptions. In this second of two companion papers, we complete the presentation and analysis of a three segment kinetic foot model by incorporating kinetic parameters and calculating joint moments and powers. The model was tested on 17 pediatric subjects (ages 7–18years) during normal gait. Ground reaction forces were measured using two adjacent force platforms, requiring targeted walking and the creation of two sub-models to analyze ankle, midtarsal, and 1st metatarsophalangeal joints. Targeted walking resulted in only minimal kinematic and kinetic differences compared with walking at self selected speeds. Joint moments and powers were calculated and ensemble averages are presented as a normative database for comparison purposes. Ankle joint powers are shown to be overestimated when using a traditional single-segment foot model, as substantial angular velocities are attributed to the mid-tarsal joint. Power transfer is apparent between the 1st metatarsophalangeal and mid-tarsal joints in terminal stance/pre-swing. While the measurement approach presented here is limited to clinical populations with only minimal impairments, some elements of the model can also be incorporated into routine clinical gait analysis.

A multi-segment foot model based on anatomically registered technical coordinate systems: Method repeatability in pediatric feet - Corrected Proof

Prabhav Saraswat, Bruce A. MacWilliams, Roy B. Davis — 2011-12-22

Highlights: ► We present a new pediatric foot model utilizing static anatomical registrations. ► A plaster mold was used to ensure consistent foot position. ► Three clinicians modeled at separate dates to measure intra-clinician variability. ► Two clinicians modeled same subjects to measure inter-clinician variability. ► Intra-clinician and inter-clinician joint angle variability were less than 4°.Abstract: Several multi-segment foot models to measure the motion of intrinsic joints of the foot have been reported. Use of these models in clinical decision making is limited due to lack of rigorous validation including inter-clinician, and inter-lab variability measures. A model with thoroughly quantified variability may significantly improve the confidence in the results of such foot models. This study proposes a new clinical foot model with the underlying strategy of using separate anatomic and technical marker configurations and coordinate systems. Anatomical landmark and coordinate system identification is determined during a static subject calibration. Technical markers are located at optimal sites for dynamic motion tracking. The model is comprised of the tibia and three foot segments (hindfoot, forefoot and hallux) and inter-segmental joint angles are computed in three planes. Data collection was carried out on pediatric subjects at two sites (Site 1: n=10 subjects by two clinicians and Site 2: five subjects by one clinician). A plaster mold method was used to quantify static intra-clinician and inter-clinician marker placement variability by allowing direct comparisons of marker data between sessions for each subject. Intra-clinician and inter-clinician joint angle variability were less than 4°. For dynamic walking kinematics, intra-clinician, inter-clinician and inter-laboratory variability were less than 6° for the ankle and forefoot, but slightly higher for the hallux. Inter-trial variability accounted for 2–4° of the total dynamic variability. Results indicate the proposed foot model reduces the effects of marker placement variability on computed foot kinematics during walking compared to similar measures in previous models.

A wide number of trials is required to achieve acceptable reliability for measurement patellar tendon elongation in vivo - Corrected Proof

Felix Schulze, Falk Mersmann, Sebastian Bohm, Adamantios Arampatzis — 2011-12-19

Abstract: The purpose of the current study was to examine the reproducibility of patellar tendon elongation measurements using brightness-mode ultrasonography (BMU) during isometric knee extension contractions. We hypothesized that the measurement of the patellar tendon elongation during only one maximal voluntary isometric knee extension contractions would not provide reliable results and that a wide number of trials is required to achieve acceptable reliability. Ten participants (eight male and two female) performed 10 isometric knee extension contractions on two separate days (5 trials on each day). Using a modified knee brace, the ultrasound probe was firmly adjusted in the sagittal plane overlying the patellar tendon. The registered ultrasound images were analyzed by three different but equally trained observers. The reproducibility was examined by the calculation of the within-day, between-day and overall coefficient of multiple correlations (wCMC, bCMC and oCMC). The Spearman–Brown prophecy formula was use to estimate the required trials to achieve the desired reliability. The wCMC, bCMC and oCMC were in average 0.824, 0.798 and 0.770, respectively, suggesting a rather moderate reproducibility of patellar tendon elongation measurements. For a high reliability (≥0.95) of tendon elongation measurements 5–6 trials are required. Finally, the results revealed an independence of the measurements from days and observers.

Sports activities are reflected in the local stability and regularity of body sway: Older ice-skaters have better postural control than inactive elderly - Corrected Proof

Claudine J.C. Lamoth, Marieke J.G. van Heuvelen — 2011-12-19

Abstract: With age postural control deteriorates and increases the risk for falls. Recent research has suggested that in contrast to persons with superior balance control (dancer's athletes), with pathology and aging, predictability and regularity of sway patterns increase and stability decreases implying a less adaptive form of postural control.The aim of the present study was to determine, whether patterns of body sway of elderly (N=13) who practice a sport which challenges postural control (ice speed-skating), are more similar to that of young subjects (N=10) than to that of inactive elderly (N=10). Trunk patterns were measured with a tri-axial accelerometer. Data were recorded during quiet upright stance with (1) eyes open, (2) limited vision, and (3) while performing a dual task. Anterior–posterior and medio-lateral acceleration time-series were analyzed. Differences in postural control were quantified in terms of the magnitude of the acceleration (root mean square), the smoothness (mean power frequency), the predictability (sample entropy) and the local stability (largest Lyapunov exponent). Postural control of ice-skating elderly differed from that of sedentary elderly. As anticipated, postural control of the ice-skating elderly was similar to that of young adults. For anterior–posterior accelerations, the skating elderly and the younger subjects had significant higher stability and lower regularity than the non-skating elderly in all tasks. These results imply that sport activities such as ice-skating are beneficial for elderly people. It might, at least partly, counteract the age related changes in postural control.

Evaluation of immediate impact of cane use on energy expenditure during gait in patients with knee osteoarthritis - Corrected Proof

2011-12-16

Highlights: ► We assessed the immediately impact of cane use in patients with OA. ► The energy expenditure and walking cost were immediately increased. ► Pain decreased during gait while using the cane for the first time.Abstract: Purpose: The aim of the present study was to assess the immediate impact of cane use on energy expenditure during gait in patients with knee OA analyzing VO2.Methods: An observational, cross-sectional study was carried out on 64 symptomatic patients with a diagnosis of knee OA. The assessment of energy expenditure was performed through an analysis of expired gases using the portable K4 apparatus (Cosmed, Model K4 b2, Italy) during the six-min walk test (6MWT). Two tests were performed with a cane and two without a cane on two different days within a seven-day period.Results: The patients walked farther on the test without the cane (p<0.001). Oxygen expenditure (VO2) and the O2 cost of walking at the end of the 6MWT increased approximately 50% and 80% during cane-assisted gait when compared to gait without the use of a cane (p<0.001). Pain (Borg scale) decreased approximately 20% at the end of the 6MWT with cane-assisted gait in comparison to gait without a cane (p<0.001).Conclusion: Cane use causes an immediate increase in energy expenditure (VO2) during gait and O2 cost of walking and an immediate decrease of pain during gait. It is necessary to do a more prolonged follow up in order to assess the impact of daily cane use on energy expenditure among these patients and determine whether adaptation occurs. Furthermore, it is necessary to study whether daily cane use has a positive impact on important parameters in these patients, such as pain, function and quality of life.

Voluntarily changing step length or step width affects dynamic stability of human walking - Corrected Proof

Patricia M. McAndrew Young, Jonathan B. Dingwell — 2011-12-16

Highlights: ► We quantify how step characteristics influence variability and stability of walking. ► We examined voluntary changes in step width and step length. ► Any change in step characteristics was associated with increased step variability. ► Short-term, voluntary changes in step width and step length affect dynamic stability.Abstract: Changes in step width (SW), step length (SL), and/or the variability of these parameters have been prospectively related to risk of falling. However, it is unknown how voluntary changes in SW and SL directly alter variability and/or dynamic stability of walking. Here, we quantified how variability and dynamic stability of human walking changed when individuals voluntarily manipulated SW and SL. 14 unimpaired, young adults walked on a treadmill at their preferred walking speed with normal gait, with a metronome and with narrower, wider, shorter and longer steps than normal. Taking narrower steps caused increased SL variability while mediolateral (ML) movements of the C7 vertebra (i.e., trunk) became locally more stable (p<0.05) and anterior–posterior (AP) C7 movements became locally less stable (p<0.05). Taking wider steps caused increased SW and SL variability, while ML C7 movements became both locally and orbitally less stable (p<0.05). Any change in SL caused increased SW, SL, and stride time variability. When taking shorter steps, ML C7 movements exhibited greater short-term local and orbital instability, while AP C7 movements exhibited decreased short-term and long-term local instability (p<0.05). When taking longer steps, AP, ML, and vertical C7 movements all exhibited increased long-term local instability and increased orbital instability (p<0.05). Correlations between mean SW, SL and dynamic stability of C7 marker motions were weak. However, short-term voluntary changes in SW and SL did significantly alter local and orbital stability of trunk motions.

Artificial balancer – Supporting device for postural reflex - Corrected Proof

2011-12-14

Abstract: The evolutionarily novel ability to keep ones body upright while standing or walking, the human balance, deteriorates in old age or can be compromised after accidents or brain surgeries. With the aged society, age related balance problems are on the rise. Persons with balance problems are more likely to fall during their everyday life routines. Especially in elderly, falls can lead to bone fractures making the patient bedridden, weakening the body and making it more prone to other diseases. Health care expenses for a fall patient are often very high. There is a great deal of research being done on exoskeletons and power assists. However, these technologies concentrate mainly on the amplifications of human muscle power while balance has to be provided by the human themself.Our research has been focused on supporting human balance in harmony with the human's own posture control mechanisms such as postural reflexes. This paper proposes an artificial balancer that supports human balance through acceleration of a flywheel attached to the body. Appropriate correcting torques are generated through our device based on the measurements of body deflections. We have carried out experiments with test persons standing on a platform subject to lateral perturbations and ambulatory experiments while walking on a balance beam. These experiments have demonstrated the effectiveness of our device in supporting balance and the possibility of enhancing balance-keeping capability in human beings through the application of external torque.

Anteroposterior stability of the knee during the stance phase of gait after anterior cruciate ligament deficiency - Corrected Proof

2011-12-14

Highlights: ► Combined DFIS and MR image based technique was used to investigate treadmill gait of the knee. ► Higher flexion angles and anterior tibial translations were found in ACL deficient knees during stance phase of gait. ► Higher flexion gait strategy of ACL injured knees could not compensate the anterior tibial translation effectively.Abstract: Quadriceps avoidance and higher flexion strategies have been assumed as effects of ACL deficiency on knee joint function during gait. However, the effect of ACL deficiency on anteroposterior stability of the knee during gait is not well defined. In this study, 10 patients with unilateral acute ACL ruptures and the contralateral side intact performed gait on a treadmill. Flexion angles and anteroposterior translation of the ACL injured and the intact controlateral knees were measured at every 10% of the stance phase of the gait (from heel strike to toe-off) using a combined MRI and dual fluoroscopic imaging system (DFIS). The data indicated that during the stance phase of the gait, the ACL-deficient knees showed higher flexion angles compared to the intact contralateral side, consistent with the assumption of a higher flexion gait strategy. However, the data also revealed that the ACL-deficient knees had higher anterior tibial translation compared to the intact contralateral side during the stance phase of the gait. The higher flexion gait strategy was not shown to correlate to a reduction of the anterior tibial translation in ACL deficient knees. These data may provide indications for conservative treatment or surgical reconstruction of the ACL injured knees in restoration of the knee kinematics during daily walking activities.

Heel height affects lower extremity frontal plane joint moments during walking - Corrected Proof

Danielle D. Barkema, Timothy R. Derrick, Philip E. Martin — 2011-12-14

Highlights: ► We examine the effect of heel height on frontal plane joint moments of the lower extremity during walking. ► Hip, knee, and ankle moments increased systematically as heel height increased during both fixed and preferred speeds. ► The systematic increase in peak internal knee abduction moment suggests higher medial compartment loading at the knee. ► Wearing high heels may put individuals at greater risk for the development of knee osteoarthritis.Abstract: Wearing high heels alters walking kinematics and kinetics and can create potentially adverse effects on the body. Our purpose was to determine how heel height affects frontal plane joint moments at the hip, knee, and ankle, with a specific focus on the knee moment due to its importance in joint loading and knee osteoarthritis. 15 women completed overground walking using three different heel heights (1, 5, and 9cm) for fixed speed (1.3ms−1) and preferred speed conditions while kinematic and force platform data were collected concurrently. For both fixed and preferred speeds, peak internal knee abduction moment increased systematically as heel height increased (fixed: 0.46, 0.48, 0.55Nmkg−1; preferred: 0.47, 0.49, 0.53Nmkg−1). Heel height effects on net frontal plane moments of the hip and ankle were similar to those for the knee; peak joint moments increased as heel height increased. The higher peak internal knee abduction moment with increasing heel height suggests greater medial loading at the knee. Kinetic changes at the ankle with increasing heel height may also contribute to larger medial loads at the knee. Overall, wearing high heels, particularly those with higher heel heights, may put individuals at greater risk for joint degeneration and developing medial compartment knee osteoarthritis.

Comparison of real-life accidental falls in older people with experimental falls in middle-aged test subjects - Corrected Proof

M. Kangas, I. Vikman, L. Nyberg, R. Korpelainen, J. Lindblom, T. Jämsä — 2011-12-14

Highlights: ► We collected acceleration data from real-life falls from older people. ► Real-life falls were compared to experimental falls from middle-aged persons. ► Fall phases based on acceleration data from real-life falls show similarities to experimental falls. ► The pre-impact phase of real-life falls shows protective actions in most falls, but not in the fall resulting in hip fracture.Abstract: Falling is a common accident among older people. Automatic fall detectors are one method of improving security. However, in most cases, fall detectors are designed and tested with data from experimental falls in younger people. This study is one of the first to provide fall-related acceleration data obtained from real-life falls. Wireless sensors were used to collect acceleration data during a six-month test period in older people. Data from five events representing forward falls, a sideways fall, a backwards fall, and a fall out of bed were collected and compared with experimental falls performed by middle-aged test subjects. The signals from real-life falls had similar features to those from intentional falls. Real-life forward, sideways and backward falls all showed a pre impact phase and an impact phase that were in keeping with the model that was based on experimental falls. In addition, the fall out of bed had a similar acceleration profile as the experimental falls of the same type. However, there were differences in the parameters that were used for the detection of the fall phases. The beginning of the fall was detected in all of the real-life falls starting from a standing posture, whereas the high pre impact velocity was not. In some real-life falls, multiple impacts suggested protective actions. In conclusion, this study demonstrated similarities between real-life falls of older people and experimental falls of middle-aged subjects. However, some fall characteristics detected from experimental falls were not detectable in acceleration signals from corresponding heterogeneous real-life falls.

Intra- and inter-foot coordination in quiet standing: Footwear and posture effects - Corrected Proof

Melissa C. Kilby, Karl M. Newell — 2011-12-14

Abstract: Intra-foot coordination between center of pressure (COP) of the ball and heel of the foot in single leg standing and inter-foot coordination of the right and left foot during bipedal stance was examined as a function of postural stance (two legs, one leg, and toe postures), footwear (barefoot, different area based high heel shoes) and postural training (ballet group and regular exercising group). Young adult females performed three 20s trials in each postural condition. In general, the traditional variability measures of COPnet motion increased under the less stable postural support conditions and ballet dancers had better balance in single leg standing. Regularity analysis revealed a negative relation between the variability of foot coupling (both intra- and inter-foot) and the standard deviation of COPnet that was mediated by the interaction of shoe support and postural stance. The findings show that shoe support and postural stance modulate collective postural motion (COPnet) through the adaptability of the coupling of foot dynamics.

Validation of an ear-worn sensor for gait monitoring using a force-plate instrumented treadmill - Corrected Proof

2011-12-14

Abstract: A force-plate instrumented treadmill (Hp Cosmos Gaitway) was used to validate the use of a miniaturised lightweight ear-worn sensor (7.4g) for gait monitoring. Thirty-four healthy subjects were asked to progress up to their maximum walking speed on the treadmill (starting at 5km/h, with 0.5km increments). The sensor houses a 3D accelerometer which measures medio-lateral (ML), vertical (VT) and anterior–posterior (AP) acceleration. Maximum signal ranges and zero crossings were derived from accelerometer signals per axis, having corrected for head motion and signal noise. The maximal force, measured by the instrumented treadmill correlated best with a combination of VT and AP acceleration (R-squared=0.36, p=0), and combined VT, ML, and AP acceleration (R-squared=0.36, p=0). Weight-acceptance peak force and impulse values also correlated well with VT and AP acceleration (Weight acceptance: R-squared=0.35, p=0, Impulse: 0.26, p=0), and combined VT, ML, and AP acceleration (Weight acceptance: R-squared=0.35, p=0, Impulse: 0.26, p=0). Zero crossing features on the ML axis provided an accurate prediction of the gait-cycle, with a mean difference of 0.03s (−0.01, 0.05 confidence intervals).

Long-term evaluation of gait initiation in six Parkinson's disease patients with bilateral subthalamic stimulation - Corrected Proof

A.M.S. Muniz, J. Nadal, K.E. Lyons, R. Pahwa, W. Liu — 2011-12-09

Highlights: ► Long-term effect of deep brain stimulation (DBS) was evaluated in Parkinson's disease. ► We applied principal component analysis on gait initiation data. ► There was a worsening in gait initiation after seven years of DBS.Abstract: Defined as the transient state between standing and walking, gait initiation is negatively affected in Parkinson's disease (PD), which often results in significant disability. Although deep brain stimulation (DBS) is the most common surgical procedure for PD, the long-term effects of DBS on gait initiation are not well studied. The present study evaluated the long-term effects of subthalamic nucleus (STN) DBS on the preparation phase of gait initiation using principal component (PC) analysis. Six patients with PD who had undergone STN DBS and 24 healthy control subjects were evaluated. PD subjects were assessed 11.3±10.3 (P1) and 78.9±10.6 (P2) months after surgery. PD subjects were tested with STN DBS in two conditions: without medication and with medication. PC analysis was applied separately for the vertical, anterior–posterior and medial–lateral components of ground reaction force (GRF) recorded during gait initiation. Three PC scores were chosen by the scree test for each GRF component and all these PC scores were used for calculating a standard distance between healthy controls and PD subjects. The Friedman test showed a significant difference in standard distance among conditions (P=0.004), with the post-hoc test recognizing differences among P1 conditions and P2 medication-on condition. The eigenvector loading factors pointed to major differences between PD conditions surrounding the maximum amplitude of vertical and anterior–posterior GRF. For the studied sample, all distances increased in the follow-up evaluation (P2) with and without medications, indicating a worsening in gait initiation after seven years.

The improvement of walking speed after cardiac rehabilitation is associated with the reduction in the metabolic cost of walking in older persons - Corrected Proof

2011-12-09

Highlights: ► We investigated a sample of older patients receiving cardiac rehabilitation. ► We assessed the energy cost of walking before and after physical training. ► We found a reduction of the energy cost of walking after physical training. ► This might explain the favourable effects of physical activity on older persons.Abstract: Background: To walk a given distance older persons consume more metabolic energy than younger adults across all speeds. As physical activity interventions improve a variety of physical performance measures in older persons, including walking speed, in this study we hypothesized that the improvement of walking speed might be associated with the reduction of the metabolic cost of walking and we tested our hypothesis in a selected sample of older patients receiving cardiac rehabilitation.Methods: In 120 patients (88 men and 32 women, mean age 74.1 years±SD 5.0) we assessed energy expenditure during the 6-min Walk Test (6mWT) before and after the rehabilitation using a portable system for direct calorimetry.Results: On the 6mWT performed after the rehabilitation patients significantly increased total energy expenditure (28.0kcal±SD 8.3 vs. 25.7kcal±SD 7.6, p<0.001), the distance walked (398m±SD 93 vs. 343m±SD 95, p<0.001) and, consequently, walking speed (1.11m/s±SD 0.26 vs. 0.95m/s±SD 0.26, p<0.001) while the metabolic cost of walking, i.e. the amount of energy used to move a body mass of 1kg for a distance of 1m, was significantly reduced (1.00cal/kg/m±SD 0.19 vs. 1.11cal/kg/m±SD 0.32, p<0.001).Conclusions: In older patients receiving cardiac rehabilitation the improvement of walking speed is associated with the improvement of walking economy. This might be a contributory factor to the favourable effects of physical activity interventions on physical performance measures.

Age-related differences in kinetic measures of landing phase lateral stability during a balance-restoring forward step - Corrected Proof

Gregory W. King, Chaitanya K. Akula, Carl W. Luchies — 2011-12-08

Highlights: ► We studied kinetic aspects of lateral stability during single-step balance recovery maneuvers. ► Older adults exhibited larger laterally directed forces during balance recovery. ► No age differences were observed in kinematic measures of lateral stability. ► Older adults appear to maintain lateral stability through increased strength usage.Abstract: Lateral stability during stepping is critical to successful balance recovery, and has been previously studied from a kinematics perspective. However, relatively little is known about the kinetic aspects of lateral stability. The purpose of this paper is to investigate age-related changes in laterally directed landing phase ground and joint reactions during a balance-restoring step response. 12 young and 13 older male adults were released from a static forward leaning position and were instructed to take a single step with the dominant leg. Laterally directed landing phase ground and ankle reactions, foot kinematics, and center of mass movement were compared across age groups. No age-related differences were observed in step width or center of mass behavior during step landing. Older adults, compared to young, demonstrated larger laterally directed landing phase ground and ankle reaction forces. The findings demonstrate an age-related increase in kinetic, but not kinematic or stability measures, suggesting that older adults do not minimize strength when maintaining stability during a single step balance recovery maneuver.

Evaluating asymmetry in prosthetic gait with step-length asymmetry alone is flawed - Corrected Proof

2011-12-08

Highlights: ► Prosthetic gait asymmetry is often evaluated in terms of step-length asymmetry. ► Step-length asymmetry depends on the relative contribution of forward foot placement and trunk progression asymmetries. ► Hence, step-length asymmetry alone is not a valid marker of prosthetic gait asymmetry. ► Adding an assessment of foot positioning relative to the trunk is recommended.Abstract: Prosthetic gait is often asymmetric in step length, but the direction of this asymmetry varies inconsistently across amputees. This situation is akin to that seen in stroke patients, where step-length asymmetry has been shown to be the additive result of asymmetries in trunk progression and asymmetries in forward foot placement relative to the trunk. The present study examined the validity of this notion in three trans-tibial and seven trans-femoral amputees wearing a unilateral prosthesis while walking over a walkway at a comfortable and slower-than-comfortable speed. The latter manipulation was added to examine the expectation that the magnitude of the trunk-progression asymmetry – attributable to a weaker propulsion generating capacity on the prosthetic side – would be smaller when walking slower because of the diminished propulsion demands. Step length, forward foot placement relative to the trunk, and trunk progression of prosthetic and non-prosthetic steps, as well as asymmetries therein, were quantified. The direction of step-length and forward foot placement asymmetries varied inconsistently across (but consistently within) participants. As expected, step-length asymmetry depended on the combination of asymmetries in forward foot placement and trunk progression, with a smaller contribution of trunk-progression asymmetry at slow speed. These results extend our previous finding for hemiplegic patients that an analysis of gait asymmetry in terms of step length alone is flawed to prosthetic gait, implying that knowledge of asymmetries in trunk progression and forward foot placement relative to the trunk is required to help elucidate the contribution of underlying impairments (viz. propulsion generating capacity) and adopted compensations on prosthetic gait asymmetry.

Influence of temporal pressure on anticipatory postural control of medio-lateral stability during rapid leg flexion - Corrected Proof

E. Yiou, T. Hussein, J. LaRue — 2011-12-08

Abstract: During leg flexion from erect posture, postural stability along the medio-lateral direction is organized in advance during “anticipatory postural adjustments” (APAs). This study aimed to investigate the influence of temporal pressure on this anticipatory postural control of medio-lateral stability. Eight young healthy participants performed series of leg flexions (1) as soon as possible in response to an acoustic signal (reaction-time condition; condition with temporal pressure) and (2) in a self-initiated condition (no temporal pressure). Results showed that APAs duration was shorter in the reaction-time condition as compared to the self-initiated condition; this shortening was compensated by an increase in the medio-lateral center-of-pressure displacement so that the dynamic stability reached at foot-off, as measured by the “extrapolated center-of-mass”, remained unchanged. It is concluded that when a complex task is performed under temporal pressure, the central nervous system is able to modulate the spatio-temporal features of APAs in a way to both hasten the initiation of the voluntary movement and maintain optimal conditions of dynamic stability. In other words, it seems that the central nervous system does not “trade off optimal stability for speed of movement initiation under reaction-time condition”, as it had been proposed in the literature.

Cycling exercise with functional electrical stimulation improves postural control in stroke patients - Corrected Proof

Hsin-Chang Lo, Yung-Chun Hsu, Ya-Hsin Hsueh, Chun-Yu Yeh — 2011-12-08

Abstract: The aim of this study is to determine whether short term functional electrical stimulation (FES)-assisted cycling training can affect the postural control of stroke patients, and whether the application of FES can enhance the effect of cycling training. 20 stroke patients were randomly assigned to the FES-cycling group (FES-CG) or the cycling group (CG). Measurements were completed before and immediately after each 20min training sessions. The measurements included a balance test (to quantify the postural control ability), a Hoffmann's reflex/motor response ratio (H/M ratio) test and a pendulum test (to quantify the muscle tone). In the balance test, some parameters in all directions exhibited significant intervention effects between the FES-CG group and the CG group. The H/M ratios (p=.014; .005, FES-CG and CG respectively) and relaxation index (p=.005; .047, FES-CG and CG respectively) revealed significant difference between FES-CG and CG group. The change ratios of directional control in the forward direction and H/M ratio revealed significant difference (p=.022; .015) between FES-CG and CG among subjects with higher muscle tone. The stroke subjects’ postural control was improved while their muscle tone was reduced after the 20min cycling training program both with and without FES. We conclude that cycling training, with or without FES may reduce spasticity in stroke patients. The application of FES in cycling exercise was shown to be more effective in stroke patients with higher muscle tone.

The effect of a long-distance run on plantar pressure distribution during running - Corrected Proof

Tine Marieke Willems, Roel De Ridder, Philip Roosen — 2011-12-07

Abstract: The purpose of this study was to assess plantar pressure alterations after long-distance running. Prior to and after a 20km run, force distribution underneath the feet of 52 participants was registered using Footscan® pressure plates while the participants ran shod at a constant self-selected pace. Peak force, mean force and impulse were registered underneath different zones of the foot. In addition, temporal data as total foot contact time, time of contact and end of contact were derived for these zones. Furthermore, a medio-lateral pressure distribution ratio was calculated in different phases of the roll-off. After the run, increases in the loading of the forefoot, midfoot and medial heel were noted and decreases in loading of the lateral toes. In the forefoot push off phase a more lateral pressure distribution was observed. The results of this study demonstrated plantar pressure deviations after long-distance running which could give additional information related to several running injuries.