Full length articleKinematic and muscle demand similarities between motor-assisted elliptical training and walking: Implications for pediatric gait rehabilitation
Introduction
Many children with physical disabilities and special health care needs experience barriers to accessing effective therapeutic technologies to improve walking and fitness. The expense of many robotic and exoskeleton technologies hinders widespread use in most clinics, school settings, and fitness facilities. Additionally, the physical labor demands associated with delivering partial body weight support (BWS) treadmill training hinders use beyond larger rehabilitation settings, particularly for children requiring physical assistance to repetitively lift and advance their legs [1], [2], [3], [4], [5].
A growing number of facilities are using the ICARE, a motor-assisted elliptical, to improve walking and fitness in adults with physical disabilities [6], [7], [8]. The device promotes movements emulating the joint motions and muscle demands of adult gait [9] and integrates design features that improve accessibility and usability (e.g., motor assistance, partial BWS, electronic height-adjustable seat, steps, ramp, wheelchair platform) compared to traditional ellipticals [7], [8]. A motor assists those with strength and/or endurance limitations to train (forward/reverse direction) at speeds up to 65 revolutions per minute (RPM). Individuals can over-ride the motor’s assistance simply by training faster than the set speed [10]. As capacity improves [6], the device is equipped to be used as a traditional elliptical with varying levels of resistance.
ICARE’s initial design criterion of a 17” minimum step length denied many children of smaller stature access to this promising tool for mass practice of a gait-like activity. Recently, this limitation was overcome by integrating a modified crank into the rear shaft to enable step length to be varied from 8” to 29” vs. the traditional 17”–29” [11]. Additionally, the pedals were inset to narrow step width and were made height adjustable so children could see and interact with the console.
The purpose of this study was to compare children’s lower extremity joint motions and muscle activation patterns during walking and training on Pedi-ICARE (Fig. 1). Given our past research with adults, we hypothesized that children’s (1) sagittal plane kinematics while training on Pedi-ICARE would closely emulate those of overground gait [9]; (2) hip, knee, and ankle muscle demands would be lower during motor-assisted Pedi-ICARE training compared to over-riding Pedi-ICARE’s motor or walking (due to motor’s assistance); (3) hip and knee muscle demands would be higher when participants over-rode Pedi-ICARE’s motor compared to gait (due to need to exert increased force to advance the pedals faster than motor and increased flexion); and (4) ankle muscle demands would be lower when participants over-rode Pedi-ICARE’s motor compared to gait (due to Pedi-ICARE’s pedals providing sustained double limb support throughout movement cycle). We expect findings from this research will provide clinicians and health care professionals with information critical to guide therapeutic exercise interventions for children seeking to regain or retain walking and fitness.
Section snippets
Participants
Twenty-one children (14 girls) without known disabilities were recruited to participate in this cross-sectional study. Eighteen children completed all conditions and formed the basis of this analysis. Their mean age was 7.9 ± 2.9 years (range 3–12 years), body mass was 30.9 ± 10.8 kg (range 16.3–46.7 kg) and height was 130.7 ± 17.9 cm (range 97–156 cm).
Instrumentation
Gait analysis was conducted along a 10-m walkway, with the middle six meters designated for data collection to eliminate the effects of acceleration and
Stride characteristics
During AAC, self-selected stride length was approximately 39% shorter and average cadence was approximately 42% slower compared to walking (Table 1). During AAC+, stride length was similar to that documented during AAC; however, average cadence increased approximately 13%.
Kinematics
Trunk, pelvis, hip, thigh, and knee movements revealed notable similarities between Pedi-ICARE training and walking; however, the ankle’s movement profile differed notably (Fig. 2). During AAC, the trunk’s shallow sinusoidal
Discussion
Task-specific training interventions are often cited as critical for promoting neuroplastic recovery and behavioral improvements in walking for children with acquired and congenital neurologic disabilities impacting locomotor function. However, many school systems, smaller clinics, and medical fitness environments lack the financial resources to purchase expensive robotic or exoskeleton devices for gait rehabilitation. Additionally, the need to care for children with a wide range of statures,
Conclusions
Children with physical disabilities and chronic conditions often require sustained rehabilitation to improve function and fitness. The similarity of trunk and lower limb motion patterns between Pedi-ICARE training conditions and walking suggests the device could be used to promote task-specific training to improve walking. The capacity to manipulate muscle demands using different motor-assistance conditions highlights Pedi-ICARE’s versatility in addressing a wide range of children’s abilities.
Conflict of interest statement
Judith M. Burnfield, Thad W. Buster, and Carl A Nelson are the inventors of the patented motor-assisted elliptical technology. The patented technology has been licensed to SportsArt for commercial distribution. The inventors receive royalties.
Statement
All authors were fully involved in the study and preparation of this manuscript. Each of the authors has read and concurs with the content of the final manuscript. The material within this submission has not been (except partial data as an abstract to conference) and will not be submitted for publication elsewhere.
Acknowledgements
The contents of this work were developed under a grant (H133G130274) initially received from the National Institute on Disability and Rehabilitation Research, Department of Education, and now funded through a grant (90IF0060) from the National Institute on Disability, Independent Living and Rehabilitation Research, Administration for Community Living. The contents of the manuscript do not necessarily represent the policy of the Department of Education or the Administration for Community Living,
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