Reduced finger and wrist flexor activity during propulsion with a new flexible handrim.
OBJECTIVE
To test the hypothesis that finger and wrist flexor activity is lower when pushing with a high-friction flexible handrim than with a standard uncoated handrim.


METHODS
Case series.


METHODS
Biomechanics laboratory.


METHODS
Twenty-four manual wheelchair users.


METHODS
Subjects pushed their own wheelchairs on a research treadmill set to level, 3 degrees , and 6 degrees grades using both a standard uncoated handrim and a high friction flexible handrim. Propulsion speed was self-selected and held constant between handrim trials. Handrim order was randomized. Finger and wrist flexor muscle activity was measured at the forearm using surface electromyography.


METHODS
Electromyographic data were rectified and normalized by each subject's maximum voluntary contraction. Total muscle exertion was determined by integrating the rectified signal over each push. Peak and total muscle exertion for each push were averaged across grade conditions and compared across handrims using a repeated measures t test.


RESULTS
The flexible handrim resulted in statistically significant reductions in both peak and total forearm muscle activation. Averaging across all subjects and grade conditions, peak muscle activation was reduced by 11.8% (P=.026) and overall muscle exertion was reduced by 14.5% (P=.016).


CONCLUSIONS
The flexible handrim was shown to require less finger and wrist flexor activity than a standard uncoated handrim for the same propulsion conditions.
Richter
W Mark
WM
MAX Mobility LLC, Beneficial Designs Inc, Nashville, TN 37211, USA. mark@max-mobility.com
Rodriguez
Russell
R
Woods
Kevin R
KR
Karpinski
Adam P
AP
Axelson
Peter W
PW
D000054:Acceleration; D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D004867:Equipment Design; D005260:Female; D005384:Finger Joint / Q000502:physiology*; D005542:Forearm / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D014910:Wheelchairs; D014955:Wrist Joint / Q000502:physiology*