Reduced Finger and Wrist Flexor Activity During Propulsion With a New Flexible Handrim

(A) The contoured elastic interface of the flexible handrim matches the shape of the hand as it grips. (B) As the user grips the elastic interface, it deforms around the hand to improve comfort and grip. (C) For extended braking, the user grips only the outer tubular handrim.

The experimental setup used in this study included a research treadmill, a surface electromyographic measurement system, and an instrumented wheel.

Linear envelopes of the electromyographic (EMG) signals taken over a single push for subject S23 with the standard and flexible handrims while on the 6° grade. Electromyographic activity is noticeably lower when using the flexible handrim. This trimodal shape was seen with some consistency. It suggests that grip is not constant during the push and that it is highest at the beginning and end of each push. Grip may be lowest in the middle of the push because the user can generate the necessary friction by pushing down radially into the handrim within that angular range.

Maximum finger and wrist flexor activity for the population of wheelchair users. The average (Avg) condition represents an average across all grades. NOTE. Error bars represent SD. *Not statistically analyzed; †P=.026.

Total finger and wrist flexor activity for the population of wheelchair users. The average condition represents an average across all grades. NOTE. Error bars represent SD. *Not statistically analyzed; †P=.016.