Are the force characteristics of synchronous handcycling affected by speed and the method to impose power?

To investigate the influence of exercise conditions (speed and method to impose power) on the applied force, force effectiveness and distribution of work during handcycling.

Ten able-bodied men performed handcycling on a treadmill. To test the effect of speed, subjects propelled at different velocities (1.38m/s, 1.66m/s, 1.94m/s) with a constant power output (35W). To test the effect of method to impose power, subjects cycled at a constant speed (1.66m/s) and different power outputs imposed by incline (1%, 2.5%, 4%) versus pulley system (simulated resistance of incline conditions). From the applied forces, fraction of effective force and work production over the propulsion cycle were calculated.

While total force (24.2 to 18.2N) and tangential force (20.0 to 13.5N) decreased significantly with higher speed, no change in lateral force was observed (3.5 to 2.8N). This resulted in a significant decrease of effectiveness (82.6 to 72.9%) and in a change of relative work distribution over the propulsion cycle (44 to 29.8J). While cycling with the highest velocity, compared to the lower velocities, more work was achieved during pulling and pressing and less work was produced while lifting the crank. No significant differences between the two methods to impose power were found in any parameter (p<0.05).

When propelling at equal power output, speed influences the force characteristics of handcycling and should be considered when analyzing force application. Since there is no difference in the force characteristics between propelling at an incline versus ground-level, results of studies examining handbike propulsion with either of these methods are largely comparable.