Table 2. Definitions of propulsion technique variables.
Variable: | Description: | Equation: |
Energy expenditure (W) | Calculated from the oxygen uptake and respiratory exchange ratioaccording to Garby and Astrup [47] | ((4.94*RER+16.04)*(1000*VO2))/60 |
Gross mechanical efficiency (%) | The percentage of internal power used for external power deliveredat the wheels | Mean power output/Energyexpenditure |
Frequency (push/min) | The number of complete pushes per minute. | (Cycletime)−1 ⋅ 60 |
Contact angle (°) | Angle at the end of a push minus the angle at the start. | Øend(i)−Østart(i) |
Max Torque/push (Nm) | The maximum torque generated around the wheel-axle within a push | Maxstart(i):end(i) (Tz) |
Pos. Work/push (J) | The torque around the wheel-axle integrated over the contactangle of the push. | ∑ start(i):end(i) (Tz ⋅ ΔØ) |
Neg. Work/cycle (J) | The torque around the wheel-axle integrated over the wheelrotation angle during the recovery phase | ∑end(i):start(i+1) (Tz ⋅ ΔØ) |
Abbrevations: start(i), start of the current push (sample); end(i), end of the current push (sample); Ø, angle (rad); Tz, torque around wheel axle (Nm).