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Table 1 Propulsion variables

From: Variability in bimanual wheelchair propulsion: consistency of two instrumented wheels during handrim wheelchair propulsion on a motor driven treadmill

Variable:

Description:

Equation:

Push time (s)

Time from the start of positive torque to the stop of positive torque for an individual push.

tend(i) - tstart(i)

Cycle time (s)

Time from the start of positive torque to the next start of positive torque.

tend(i) − tend(i − 1)

Contact angle (rad)

Angle at the end of a push minus the angle at the start.

Øend(i) − Østart(i)

Fpeak (N)

3d peak force during the push phase

Maxstart : end(Fx2 + Fy2 + Fz2)0.5

Mean Power/push (W)

The mean power during the push phase.

Meanstart : end(Tz • Δ Ø)

Work/push (J)

The power integrated over the duration of the push.

∑start : end(Tz • Δ Ø)

Frequency (push/min)

Pushes per minute.

Npushes/Δ t

Mean power/minute (W)

The mean total (unilateral) power (Tz*Angular velocity) during a complete series of cycles in a minute multiplied by 2.

2 • (∑start(i) : start(n)(Tz • Δ Ø))

  1. Abbrevations: t, time(s); start(i), start of the current push (sample); end(i), end of the current push (sample); Ø, angle (rad); Fx, Fy and Fz, force components (N); Tz, torque around wheel axle (Nm).