Mechanical efficiency and wheelchair performance during and after spinal cord injury rehabilitation.

The purpose of the present study was to investigate whether mechanical efficiency (ME) relates to wheelchair propulsion capacity and wheelchair performance tasks during and after rehabilitation of people with a spinal cord injury (SCI). Eighty participants with a SCI were tested during rehabilitation (3 x) and 1 year after discharge. Two 3-minute submaximal exercise blocks, a maximal wheelchair exercise test, and four wheelchair performance tasks were performed. ME, peak power output (PO (peak)), the sum of the performance times of a 15-m sprint and figure-of-eight, and the heart rate reserve (%HRR) during 10 s of wheelchair propulsion on a 3 % and 6 % slope were calculated. The relationship between ME and PO (peak), %HRR and performance time was tested with a multilevel regression analysis. ME showed a significant relationship with PO (peak) (p </= 0.002). A 1 % higher ME related to a 1.6 - 2.2 W higher PO (peak). ME of exercise block 2 was related to the sum of the performance times of a 15-m sprint and figure-of-eight; the tests were performed faster by participants with a higher ME. No relationship was found between ME and %HRR during wheelchair propulsion on a slope. ME showed a significant effect on wheelchair propulsion capacity and wheelchair performance time during and 1 yr after SCI rehabilitation although the isolated effect of ME is small.