| | Kinematics of stair descent in young and older adults and the impact of exercise trainingReceived 20 July 2005; received in revised form 16 December 2005; accepted 18 December 2005. published online 15 February 2006. Abstract Stair descent is a challenging task in old age. This study firstly investigated lower extremity kinematics during stair descent in young (YOU) and healthy, community dwelling older adults (OLD). Secondly, the impact of an exercise training intervention on age-related differences in stair descent was assessed. At baseline, a motion analysis system was used to determine spatio-temporal gait variables and lower extremity kinematics as YOU (n =23, age=27±3 years) and OLD (n=34, age=73±4 years) descended a three step staircase. The older adults were then divided into training (TRA) and control (CON) groups. For 12 months, TRA performed resistance, aerobic, balance, and flexibility exercises under supervision in a class environment (twice per week) and unsupervised at home (once per week). CON carried on with normal daily activities. Following the intervention, baseline measurements were repeated in TRA and CON. At baseline, total descent, stride cycle, and single support times were longer in OLD than in YOU. In addition, sagittal plane knee motion was lower in OLD whilst frontal and transverse plane pelvis and hip motion were higher in OLD. Exercise training did not reduce the age-related differences observed. In conclusion healthy older adults perform stair descent at a slower speed and with greater motion outside the plane of progression than young adults. We found no evidence that these differences are reduced by generic exercise training, at least in non-frail older adults. 1. Introduction  The incidence of falling rises in those aged 65 and over and this has severe consequences in terms of morbidity, mortality and healthcare cost [1]. Injuries related to falls on staircases, in particular, increase in old age [2] and are one of the leading causes of fall-related injuries [3], [4] highlighting the challenging nature of stair negotiation. The mechanics of stair negotiation in young adults have been comprehensively described [5], [6], [7], [8]. A handful of studies have reported on some elements of the mechanics of stair negotiation in middle and old aged individuals [9], [10], [11], [12], [13], although these studies lack comparison with a younger control group. To our knowledge the only detailed biomechanical comparisons of younger and older adults concentrate exclusively on ground reaction force parameters [14], [15]. A comprehensive description of lower extremity motion in older adults during stair negotiation could not be found in the literature. Alterations in mechanics of stair descent (and gait mechanics in general) in old age are caused by and/or compensate for age-related decline in physiological characteristics. For example stair negotiation demands a substantial percentage of maximum strength capacity in older adults [16]. Poor vision, proprioception, balance, and cardiovascular health are also likely to contribute to reduction in stair negotiation ability [4]. Older adults experience well established benefits from structured exercise training in terms of musculoskeletal, cardiovascular, and balance fitness [17]. A number of studies have demonstrated transfer of such benefits to gait characteristics, including walking speed, endurance, and stability [18], [19], [20]. However, the impact of physical fitness and exercise training on stair negotiation has not been well established. Previous investigations focussed only on speed of stair negotiation as an overall performance indicator. For example, cross-sectional analyses have revealed positive relationships between speed of stair negotiation and lower extremity muscle cross-sectional area, isometric torque, and power [21], [22], [23]. Similarly, in intervention studies, improvement in speed of stair negotiation [24], [25] has been observed to accompany improvement in muscle size and strength following resistance training of frail older adults. No information is presently available on the impact of improvement in physiological capacity through exercise training on the mechanics of stair negotiation in older adults. The first aim of this investigation was to compare lower extremity motion during stair descent in young and healthy older adults. The second aim was to determine whether 12 months of exercise training had a beneficial impact on lower extremity stair descent kinematics in healthy older adults. We focussed on descent because it is more challenging than ascent from a dynamic stability perspective [7]. Furthermore, injuries due to falls during descent outnumber those during ascent by three to one [3]. 2. Methods 2.1. Participants Thirty-four older adults (OLD, aged 69–82 years) from the local community were recruited to the study having responded to advertisement in the local press and having passed pre-trial screening. All participants were healthy, living independently in the local community, free from gait impairment or chronic disease, and were given medical clearance by their general practitioner to undertake the exercise training protocol prescribed in the present study. Furthermore, all participants were capable of descending the staircase used in this study without using a handrail. Baseline data were compared to a sample of 23 young adults (YOU, aged 20–29 years) recruited from the university student and staff population. We observed no difference between males and females in spatio-temporal gait parameters in either YOU or OLD, thus data for males and females were pooled in the current study. The older participants were assigned to a training group (TRA) or a non-training control group (CON). After the withdrawal during the study of three TRA and three CON participants, 14 TRA and 14 CON were available for analysis of the effect of intervention. All measurements were made pre- and post-intervention. Post-intervention measurements were completed within 2 weeks from completion of the intervention period. All methods and procedures were approved by our institution's ethics committee. 2.2. Protocol Experiments were conducted on a three step staircase (rise=17cm, tread=28cm, width=50cm) with force plates mounted in each step (Kistler type 9286AA, Kistler Instruments, Winterthur, Switzerland) and in the ground (Kistler type 9253A) directly in front of the staircase (Fig. 1). A kinetic analysis was not undertaken in this study because of a malfunction of the integrated force plate amplifiers not allowing accurate recording of forces higher than 243N, however ground reaction forces (GRF) were used to define foot contact and foot off times using a 10N vertical GRF threshold [26]. After several familiarisation trials participants stood on the extended platform at the top of the staircase and walked down after a cue from the investigator. All participants were given the instruction to walk down at their normal pace, to use their left leg for the first step, to only place one foot on each step (foot-over-foot descent), and to continue walking in a straight line for 5m upon reaching the bottom of the staircase. Total stair descent time was measured from foot contact on step one to foot off on the ground force platform. Kinematic analysis (details in Section 2.3) was performed on the stride defined by foot contact with step two to foot contact with the ground immediately beyond the staircase. All participants performed six trials without using the handrails. Any trials with visible hesitation, misplaced footing, or stumbles were excluded from further analysis. There were no exclusions in the YOU group, and of all trials by older adults seven (<2%) were excluded. Three trials per participant were randomly selected to determine within-subject averages of the variables of interest. 2.3. Motion analysis A nine camera motion analysis system (Vicon 612, Oxford Metrics, UK) sampling at 120Hz captured 15 retro-reflective markers placed bilaterally on the lower extremity [27]. From filtered marker trajectories [28] the software calculated joint and segment angles (Vicon Bodybuilder plug in gait model, Oxford Metrics, UK). This model determines instantaneous embedded, orthogonal coordinate systems for the pelvis, thigh, shank, and foot based on marker trajectories and predicted joint centre locations. Cardan angles are then derived from the orientation of one coordinate system relative to another. Pelvic angles are relative to the global reference frame, whilst hip, knee, and ankle angles refer to the relative orientation of adjacent lower extremity segments. Sagittal, frontal, and transverse plane angles were investigated for the pelvis and hip. Frontal and transverse plane knee and ankle angles were not considered, in part because of inadequate signal to noise ratio [29]. Therefore, for the knee and ankle, we only considered sagittal plane angles. The same individual placed the markers in all trials, was well practiced in this task prior to the commencement of the study, and strictly adhered to the instructions provided by Vicon. We assumed that using this approach led to adequate intra-trial reliability for joint kinematic data. For statistical comparison of joint/segment angles between groups/conditions the following discrete variables were obtained from individual trials: maximum, minimum, and range of motion (ROM). Ensemble average curves were then constructed for presentation by transforming the time series data into discrete points at each 2% of the gait cycle. Standard temporal and spatial gait parameters were also measured for statistical comparison. 2.4. Intervention Participants in TRA underwent a 12 months tailored exercise program for older individuals. The programme was intended to incorporate exercises to target the causes of muscle weakness, poor balance, and poor mobility. Each week, participants attended two supervised sessions (held at a gym and led by a certified instructor) and completed one home based session. All sessions lasted 1h. Each supervised session commenced with 10min of warm up activities. This was followed by a 12min, instructor led, group aerobic workout involving low impact walking and stepping with changes of direction to challenge balance maintenance. This included for example, forward, backward, side and diagonal heel and toe taps; forward, backward, and sideway walks; knee raises and lunges. Upper body movements such as arm raises, crosses, and curls were also incorporated into these movements. This was set to music paced at 118–124 beats per minute and was followed by 25min of resistance training. Two sets (increasing to 3 after 6 months) of 8–10 repetition maximums were performed on each of the following machines: leg press, leg extension, calf raise, chest press, and seated row. Training load was reviewed and adjusted at the start of each month. In addition, elastic resistance bands were used to strengthen muscle groups not targeted specifically by the resistance machines. The final 10min included a cool down period, involving stretching of the major muscle groups and tai chi exercises. For the home based session, participants followed a guide book provided by the investigators. This session involved a brisk walk (20–40min) followed by strengthening of major muscle groups with resistance bands and stretching exercises (20min). Adherence was good with participants attending, on average, 91% of supervised sessions and reporting completion of 92% of home based sessions. Subjects in CON carried on with their normal daily activities and were asked not to take on new vigorous activities. We have reported the findings regarding the impact of this intervention on typical muscle strength and functional ability parameters in the present participants elsewhere [30], [31]. In particular, training led to significant improvements in triceps surae volume (+12%) and plantar flexor isometric strength (+20%) [30], as well as improvements in knee extensor isometric strength (+17%), knee extensor power (+32%), maximum distance walked in 6min (+7%), and time taken in the get up and go test (−12%) [31]. No improvements were observed in non-training controls. 3. Results 3.1. Age effects Physical characteristics of YOU and OLD are shown in Table 1. YOU were 5cm taller than OLD (p<0.05), but leg length and body mass were similar. Stair descent was slower in OLD as shown by longer total descent, stride cycle, and single limb support durations (p<0.05, Table 2). Total double support time, percentage of stride time spent in stance, step width, and foot clearance were similar between groups (Table 2). Ensemble average joint angle curves are plotted in Fig. 2 and joint angle data are shown in Table 3. In the sagittal plane, no differences were observed in pelvic tilt, hip flexion/extension, or ankle dorsiflexion/plantarflexion. However, reduced peak knee flexion in early swing was observed in OLD (p<0.05). This led to a smaller knee ROM in OLD (p<0.05). More pronounced age-related differences were present in the frontal and transverse planes. In the frontal plane, increased obliquity of the pelvis was observed (ipsilateral side higher) (max; p<0.05) and the hip was more adducted (max; p>0.05) in the second half of stance in OLD (max; p<0.05). These differences resulted in greater frontal plane ROM for the pelvis and hip in OLD (p<0.05). In the transverse plane, pelvic rotation (ipsilateral side protracted) in early stance and pelvic external rotation in late stance both tended to be slightly higher in OLD, although the differences in peak values were not significant. Internal hip rotation in late stance was greater in OLD (max; p<0.05). These differences led to greater transverse plane ROM for pelvis and hip in OLD (p<0.05). 4. Discussion The first aim of this study was to investigate differences in stair descent kinematics between young and healthy older adults. The main findings in this regard were that: (1) OLD performed stair descent at a slower speed than YOU; (2) motion in the sagittal plane was similar apart from reduced peak knee flexion in OLD; (3) hip and pelvic motion in the frontal and transverse planes was increased in OLD. The second aim of this study was to determine if an exercise training intervention could reduce the age-related differences observed at baseline. We found no evidence of a reduction of these differences after the exercise training intervention. To our knowledge no previous study has reported a comprehensive comparison of joint kinematics in young and older adults during stair negotiation. However, studies have investigated sagittal plane joint angles during a single step down from a raised platform [32], [33]. Hortobagyi and DeVita [32] observed less knee and ankle motion in the lead leg of older adults during loading, which would indicate increased leg stiffness. Lark et al. [33] observed increased ankle dorsiflexion in older adults in the trail leg as it controlled the lowering of the body. This was interpreted as a safer strategy than the plantarflexion/forefoot weight-bearing strategy employed by younger adults, as this allowed a flat foot position to be maintained for longer. Such differences were not apparent in the current study suggesting that these observations [32], [33] might be specific to a single step down, the transition from stair to level ground, or to a step by step stair descent technique rather than dynamic foot over foot descent. Stepping down was also performed on boxes up to 33cm in height which is approximately double the stair height used in the current study. During level walking, observations of sagittal plane motion in older adults include decreased plantarflexion and hip extension during push off, and increased knee flexion at contact relative to young adults [34], [35], [36]. These observations are related to a shortened stride (at a slower speed) in older individuals. During stair negotiation stride length is constrained by the dimensions of the staircase, therefore differences in motion related to stride length are not expected. Similarly, stride width (base of support) was not different between groups and therefore did not systematically affect joint kinematics. Hence we do not consider the differences in joint kinematics observed in the current study to be a simple consequence of a slower, safer strategy. The only difference in sagittal plane motion observed in the current study was a decrease in knee ROM in OLD due to decreased peak flexion in early swing. A similar finding during level gait was made in a previous study [34] but not in others [35], [36]. The requirement for knee flexion is greater in stair descent than in level gait in order to lower the body towards the step below. The reduction in knee flexion may be linked to differences in frontal plane hip/pelvis motion and is further discussed later. We observed increased frontal and transverse plane motion of the hip and pelvis as OLD descended the staircase. Increased frontal plane hip motion resulted from increased hip adduction in late stance. Increased transverse plane hip motion was due to increased internal hip rotation in late stance. The increased frontal/transverse plane pelvic motion in OLD may be mechanically linked to these observations at the hip. Increased hip adduction in stance during stair descent in OLD is similar to observations made during level gait [34]. In contrast to increased frontal/transverse pelvic motion during stair descent in OLD, decreased frontal/transverse pelvic motion has been observed during level gait [34], a difference which may be related to the more challenging nature of stair descent. The increased frontal/transverse plane motion may be related to insufficient neuromuscular control. During single stance, the body centre of mass is located medial to the weight-bearing hip joint. This contributes to a large external moment that tends to adduct the hip. This moment has been shown to be larger during stair descent than in other activities of daily living and is larger than other external moments about the hip or knee [12]. A large opposing internal hip abductor moment is required to control hip adduction in stance. Therefore, increased hip adduction and pelvic motion during stair descent in OLD may reflect hip abductor weakness in old age [37]. Similarly, weakness of the external hip rotators might be related to increased stance phase internal hip rotation, and hence, increased hip and pelvic transverse plane motion. There may be a link between the observed changes in frontal plane hip/pelvis motion and sagittal plane knee motion in OLD: increased hip adduction in late stance and associated drop of the pelvis on the contralateral side could contribute to lowering the body to the next step, potentially reducing the need for knee flexion in terminal stance for this task. Whilst the reduced peak knee flexion reported in Section 3 refers to early swing, further analysis revealed that knee flexion at the end of stance (foot off) was also lower in OLD (YOU 86.8±4.2° versus OLD 80.8±5.1°; p<0.05). Therefore reduced knee flexion in OLD may be a consequence of insufficient medio-lateral control about the hip. Alternatively, increased medio-lateral hip/pelvis motion may represent a compensatory mechanism to reduced knee flexion range of motion in OLD [33], [38]. Evidence for decreased stability during stair negotiation in old age comes mainly from epidemiological observations of increased stairway accidents in older adults [2]. However, strong direct biomechanical evidence of reduced stability on stairs is lacking and a more cautious approach in older adults is often interpreted as a compensatory strategy to overcome inherent instability. In previous analyses of GRF parameters during stair negotiation, lower anterior shear force and coefficient of friction required to prevent slipping during descent [14], and lower loading rate and peak vertical force during ascent [15] were suggestive of a more cautious strategy in older adults. In the current study OLD adopted a slower speed, consistent with a more conservative approach. Hip musculature has a vital role in medio-lateral postural stability [39]. Therefore, if the increased hip/pelvis motion during stair descent in OLD is reflective of impaired neuromuscular control around the hip joint as speculated earlier, this could potentially contribute to an increased risk of balance loss and falling on stairs in old age. The second part of this study involved investigating whether a 1 year exercise training intervention had a beneficial impact on stair descent kinematics in older adults. To our knowledge this is the first study to investigate stair negotiation variables, other than speed, as outcome measures following exercise training in older adults. As noted earlier, we have shown elsewhere that the exercise intervention had a beneficial impact on muscle size, strength and power of the participants used in this study [30], [31]. Speed of stair negotiation has been related to muscle size, strength, and power [21], [22], [23]. However, we observed no increase in speed following the exercise intervention (although it is possible that a full size staircase may have been necessary to detect a subtle change in speed). We also found no evidence of a reduction in the age-related differences in joint motion following the intervention. We should reinforce that whilst OLD descended the staircase more slowly and with differences in joint kinematics compared to YOU, they were a healthy group without clinical balance or mobility difficulties. Furthermore, all had sufficient strength and balance to descend the staircase without using the handrail. Our observations are in contrast to those in frail older adults, who clearly increase their speed of stair negotiation following resistance training [24], [25]. Given these findings it could be suggested that the intervention used lacked volume/intensity to significantly impact on mobility in our healthy group of older adults without functional limitations. We do not believe this to be the case, since other measures of mobility, such as maximum distance walked in 6min and the time taken to perform the timed up and go test were significantly improved following the current exercise intervention [31]. A more likely explanation is that the intervention may have lacked specificity to impact on stair descent as discussed below. Interventions that target only one specific task (e.g. stair descent) have limited application. The current analysis was one component of a larger study aimed at investigating the reversibility of several aspects of reduced physiological function and mobility in old age. The generic nature of the intervention is advocated by relevant organisations [17] for improving physical well-being and therefore our observations have wide application. Some potential reasons can be offered for the lack of transfer of improvement in general physiological capacity to stair descent performance. First, stair descent involves controlled lowering (eccentric muscle work). By design, traditional resistance machines as used in this intervention prioritise improvement in concentric strength. A recent study found that training using eccentric ergometers improved stair descent speed in frail older adults whilst training using conventional resistance machines did not [25]. Second, given the observed increase in hip and pelvis motion in OLD, resistance training of frontal and transverse plane hip muscles may be key factors to improve stair negotiation. In the current intervention, some exercises involving relatively lightweight elastic resistance bands targeted the hip abductors and external rotators but the loading may have been inadequate to induce significant strength improvements in these muscles. Third, the aerobic component of the intervention included exercises designed to challenge dynamic balance maintenance, however performing similar exercises whilst changing levels (e.g. using a stepping box) may have been more beneficial for stair negotiation. In conclusion, healthy community dwelling older adults perform stair descent at a slower speed and with greater motion outside of the plane of progression than young adults. We found no evidence that these differences are reduced by generic exercise training. Acknowledgements Supported by European Commission Framework V funding (‘Better-Ageing’ Project, No. QLRT-2001-00323). The resistance machines were provided courtesy of Technogym®. We thank Andrea Muirhead for delivering the training programme. References [1]. [1]American Geriatrics Society, British Geriatrics Society, American Academy of Orthopaedic Surgeons Panel on Falls Prevention. Guideline for the prevention of falls in older persons. J Am Geriatr Soc. 2001;49:664–672. MEDLINE |
CrossRef
[2]. [2]Hemenway D, Solnick SJ, Koeck C, Kytir J. The incidence of stairway injuries in Austria. Accid Anal Prev. 1994;26:675–679. MEDLINE |
CrossRef
[3]. [3]Svanstrom L. Falls on stairs: an epidemiological accident study. Scand J Soc Med. 1974;2:113–120. MEDLINE [4]. [4]Startzell JK, Owens DA, Mulfinger LM, Cavanagh PR. Stair negotiation in older people: a review. J Am Geriatr Soc. 2000;48:567–580. MEDLINE [5]. [5]Andriacchi TP, Andersson GB, Fermier RW, Stern D, Galante JO. A study of lower-limb mechanics during stair-climbing. J Bone Joint Surg Am. 1980;62:749–757. MEDLINE [6]. [6]McFadyen BJ, Winter DA. An integrated biomechanical analysis of normal stair ascent and descent. J Biomech. 1988;21:733–744. MEDLINE |
CrossRef
[7]. [7]Zachazewski JE, Riley PO, Krebs DE. Biomechanical analysis of body mass transfer during stair ascent and descent of healthy subjects. J Rehabil Res Dev. 1993;30:412–422. MEDLINE [8]. [8]Riener R, Rabuffetti M, Frigo C. Stair ascent and descent at different inclinations. Gait Posture. 2002;15:32–44. Abstract | Full Text |
Full-Text PDF (1304 KB)
|
CrossRef
[9]. [9]James B, Parker AW. Electromyography of stair locomotion in elderly men and women. Electromyogr Clin Neurophysiol. 1989;29:161–168. [10]. [10]Simoneau GG, Cavanagh PR, Ulbrecht JS, Leibowitz HW, Tyrrell RA. The influence of visual factors on fall-related kinematic variables during stair descent by older women. J Gerontol. 1991;46:M188–M195. MEDLINE [11]. [11]Kirkwood RN, Culham EG, Costigan P. Hip moments during level walking, stair climbing, and exercise in individuals aged 55 years or older. Phys Ther. 1999;79:360–370. MEDLINE [12]. [12]Luepongsak N, Amin S, Krebs DE, McGibbon CA, Felson D. The contribution of type of daily activity to loading across the hip and knee joints in the elderly. Osteoarthr Cartilage. 2002;10:353–359. [13]. [13]Nadeau S, McFadyen BJ, Malouin F. Frontal and sagittal plane analyses of the stair climbing task in healthy adults aged over 40 years: what are the challenges compared to level walking?. Clin Biomech. 2003;18:950–959. [14]. [14]Christina KA, Cavanagh PR. Ground reaction forces and frictional demands during stair descent: effects of age and illumination. Gait Posture. 2002;15:153–158. Abstract | Full Text |
Full-Text PDF (199 KB)
|
CrossRef
[15]. [15]Stacoff A, Diezi C, Luder G, Stussi E, Kramers-de Quervain IA. Ground reaction forces on stairs: effects of stair inclination and age. Gait Posture. 2005;21:24–38. Abstract | Full Text |
Full-Text PDF (225 KB)
|
CrossRef
[16]. [16]Hortobagyi T, Mizelle C, Beam S, DeVita P. Old adults perform activities of daily living near their maximal capabilities. J Gerontol A: Biol Sci Med Sci. 2003;58:M453–M460. MEDLINE [17]. [17]American College of Sports Medicine. Position stand: exercise and physical activity for older adults. Med Sci Sports Exerc. 1998;30:992–1008. MEDLINE |
CrossRef
[18]. [18]Judge JO, Underwood M, Gennosa T. Exercise to improve gait velocity in older persons. Arch Phys Med Rehabil. 1993;74:400–406. MEDLINE [19]. [19]Ades PA, Ballor DL, Ashikaga T, Utton JL, Nair KS. Weight training improves walking endurance in healthy elderly persons. Ann Intern Med. 1996;124:568–572. MEDLINE [20]. [20]Hausdorff JM, Nelson ME, Kaliton D, Layne JE, Bernstein MJ, Nuernberger A, et al. Etiology and modification of gait instability in older adults: a randomized controlled trial of exercise. J Appl Physiol. 2001;90:2117–2129. [21]. [21]Bassey EJ, Fiatarone MA, Oneill EF, Kelly M, Evans WJ, Lipsitz LA. Leg extensor power and functional performance in very old men and women. Clin Sci. 1992;82:321–327. [22]. [22]Masuda K, Kim J, Kinugasa R, Tanabe K, Kuno S-Y. Determinants for stair climbing by elderly from muscle morphology. Percept Mot Skills. 2002;94:814–816. MEDLINE |
CrossRef
[23]. [23]Ploutz-Snyder LL, Manini T, Ploutz-Snyder RJ, Wolf DA. Functionally relevant thresholds of quadriceps femoris strength. J Gerontol A: Biol Sci Med Sci. 2002;57:B144–B152. MEDLINE [24]. [24]Fiatarone MA, O’Neill EF, Ryan ND, Clements KM, Solares GR, Nelson ME, et al. Exercise training and nutritional supplementation for physical frailty in very elderly people. N Engl J Med. 1994;330:1769–1775. MEDLINE |
CrossRef
[25]. [25]LaStayo PC, Ewy GA, Pierotti DD, Johns RK, Lindstedt S. The positive effects of negative work: increased muscle strength and decreased fall risk in a frail elderly population. J Gerontol A: Biol Sci Med Sci. 2003;58:M419–M424. MEDLINE [26]. [26]Tirosh O, Sparrow WAT. Identifying heel contact and toe-off using force plate thresholds with a range of digital-filter cutoff frequencies. J Appl Biomech. 2003;19:178–184. [27]. [27]Kadaba MP, Ramakrishnan HK, Wootten ME. Measurement of lower-extremity kinematics during level walking. J Orthop Res. 1990;8:383–392. MEDLINE |
CrossRef
[28]. [28]Woltring HJ. A fortran package for generalized, cross-validatory spline smoothing and differentiation. Adv Eng Softw. 1986;8:104–113. [29]. [29]Davis RB, Ounpuu S, Tyburski D, Gage JR. A gait analysis data collection and reduction technique. Hum Mov Sci. 1991;10:575–587.
CrossRef
[30]. [30]Morse CI, Thom JM, Mian OS, Muirhead A, Birch KM, Narici MV. Muscle strength, volume and activation following 12-month resistance training in 70-year-old males. Eur J Appl Physiol. 2005;95:197–204. MEDLINE [31]. [31]Thom JM, Morse CI, Mian OS, Muirhead A, Birch KM, Narici MV. Recovery of muscle strength and functional performance with strength training in old age. In: Roi GS, Nanni G editor. XIV International Congress on Sports Rehabilitation and Traumatology: The Accelerated Rehabilitation of the Injured Athlete. Bologna, Italy. 2005;p. 36–37. [32]. [32]Hortobagyi T, DeVita P. Altered movement strategy increases lower extremity stiffness during stepping down in the aged. J Gerontol A: Biol Sci Med Sci. 1999;54:B63–B70. MEDLINE [33]. [33]Lark SD, Buckley JG, Jones DA, Sargeant AJ. Knee and ankle range of motion during stepping down in elderly compared to young men. Eur J Appl Physiol. 2004;91:287–295. MEDLINE |
CrossRef
[34]. [34]Judge JO, Davis RB, Ounpuu S. Step length reductions in advanced age: the role of ankle and hip kinetics. J Gerontol A: Biol Sci Med Sci. 1996;51:M303–M312. MEDLINE [35]. [35]Kerrigan D, Todd M, Croce U, Lipsitz L, Collins J. Biomechanical gait alterations independent of speed in the healthy elderly: evidence for specific limiting impairments. Arch Phys Med Rehabil. 1998;79:317–322. Abstract |
Full-Text PDF (785 KB)
|
CrossRef
[36]. [36]DeVita P, Hortobagyi T. Age causes a redistribution of joint torques and powers during gait. J Appl Physiol. 2000;88:1804–1811. [37]. [37]Johnson ME, Mille ML, Martinez KM, Crombie G, Rogers MW. Age-related changes in hip abductor and adductor joint torques. Arch Phys Med Rehabil. 2004;85:593–597. Abstract | Full Text |
Full-Text PDF (100 KB)
|
CrossRef
[38]. [38]Roach KE, Miles TP. Normal hip and knee active range of motion: the relationship to age. Phys Ther. 1991;71:656–665. MEDLINE [39]. [39]Winter DA. Human balance and posture control during standing and walking. Gait Posture. 1995;3:193–214. Abstract |
Full-Text PDF (2515 KB)
|
CrossRef
a Institute for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Hassall Road, Alsager, Cheshire ST7 2HL, United Kingdom b School of Sport, Health and Exercise Sciences, University of Wales, Bangor, Gwynedd LL57 2PX, United Kingdom  Corresponding author. Tel.: +44 161 247 5515; fax: +44 161 247 6375.
PII: S0966-6362(06)00009-9 doi:10.1016/j.gaitpost.2005.12.014 © 2006 Elsevier B.V. All rights reserved. | |
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