Correcting the Wingate Test for Changes in Kinetic Energy of the Ergometer Flywheel

Abstract

The rotating flywheel of a cycle ergometer possesses kinetic energy (KE) by virtue of its rotation about the center of mass. The energy released as the flywheel velocity (FV) decreases during the course of a Wingate test is used to accomplish mechanical work. The subject should not be “credited” with this work since the energy storage occurred prior to the start of the 30-s test. The total KE (KE_total) in the flywheel of a Monark ergometer was determined using the formula KE_total = 1/2 Iω². The KE available to do work (KE_work) was measured by loading the ergometer with 1 Kp (9.8 N), spinning it at predetermined rates, and observing the number of revolutions completed as it coasted to a stop. The difference between KE_total and KE_work was attributable to friction. The mechanical power supplied by the flywheel in any 5-s period of the Wingate test was found to be:

Flywheel power (W) = .00185 (FVstart²-FV_end ²)/5s

where FV is expressed in rpm. This indicates that Wingate test scores should be corrected by subtracting the flywheel power output from the total power output. The correction lowers peak power (PP), mean power (MP), and fatigue index (% fatigue) by 6.2%, 3.0%, and 6.6% in active male subjects (P < 0.05).

Key words

Wingate - anaerobic - cycle ergometer - kinetic energy - flywheel - moment of inertia