Biophysical aspects of submaximal hand cycling.

Hand cycling is a popular form of wheeled mobility. This study evaluates biophysical differences between synchronous/asynchronous hand cycling. During submaximal hand cycling on a motor driven treadmill, 9 able-bodied subjects performed 2 series of 4 steady state exercise bouts at 1.11 to 2.78 m/s. Metabolic parameters, mean force on the handle bar, muscle activity and local perceived exertion in the upper body were determined. Mean power output was 35.4 +/- 7 W (v = 2.78 m/s). At this speed oxygen uptake was 1.11 +/- 0.25 and 1.26 +/- 0.26 l/min for the synchronous and asynchronous modes, respectively. Mechanical efficiency was significantly higher (v = 2.78 m/s: + 11.5 %) in synchronous cycling. Higher activity of m. obliquus externus and extensor carpi ulnaris was seen. Mean 2D total force and fraction effective force on the handle bar were lower in asynchronous hand cycling. Local perceived discomfort was higher in the asynchronous mode for different arm regions. Synchronous hand cycling is more efficient and at a lower metabolic cost. Mean muscle activation and the local perceived discomfort may explain some results. Future study should focus on combined time-based force and muscle activity characteristics. Synchronous hand cycling should be preferred during submaximal exercise in early rehabilitation.