Fig 1.
Overview of the protocol and the experimental set-up.
The participants rode on a motorized treadmill (slope 0°) at a velocity of 1.94 m/s, while the oxygen consumption and heart rate were continuously measured. To impose extra resistance, a pulley system was attached to the back of the handcycle, to add 10 W and 20 W, respectively.
Fig 2.
Handcycle and coordinates system.
(A) Attach-unit handcycle used in current study with (B) the according 3D coordinates system in the left handlebar. Alpha = angle between crank and axis. Beta = angle between handle and crank. Frad is positive directed towards crank axis, Flat is positive directed leftwards (out of the paper) and Ftan is positive directed counterclockwise.
Table 1.
Mean (standard deviation) of all participants (n = 11) for the nine handcycle conditions (at 1.94 m/s) and the outcomes of the statistical test for the physiological parameters and the force components.
Fig 3.
Effects of three cadences and three resistance settings on mean gross mechanical efficiency (%).
The mean value and the standard deviation (n = 11) are given for all nine conditions. Significant results following post-hoc pairwise comparisons (Bonferroni corrected): **: P<0.01; ***: P<0.001.
Fig 4.
Effects of three gear ratios and three resistance settings on mean fraction of effective force (%).
The mean value and the standard deviation (n = 11) are given for all nine conditions. Significant results following post-hoc pairwise comparisons (Bonferroni corrected): *: P<0.05; **: P<0.01; ***: P<0.001.
Fig 5.
The tangential force component (propulsion force) at the left handlebar for all nine conditions.
The view is from the left. The mean graphs (and standard deviation) of full cycles (without freewheeling cycles) from the last minute of handcycling at 1.94 m/s of all participants (n = 11) are given. The starting angle (crank angle = 0°) was defined as the crank pointing towards the participant. The forward propulsion is directed counterclockwise. To smoothen the graph, an additional second order Butterworth filter with a cut-off frequency of 10 Hz was applied to the tangential force data for displaying purposes only.