Martin, J. C., & Brown, N. A. (2009). Joint-specific power production and fatigue during maximal cycling. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 2772.

"Cycling power decreases substantially during a maximal 30 s cycling trial. It is not known whether powers produced at each joint decrease to a similar extent or if each joint exhibits an individual fatigue profile. Changes in movement patterns and/or relative joint powers with fatigue could arise from several different mechanisms or from a complex interplay of mechanisms."

This investigation determined changes in movement and power at each joint during a fatiguing an aerobic cycling trial. Trained cyclists performed (N = 13) a 30-second maximal isokinetic cycling trial at 120 rpm. Pedal forces and limb kinematics were recorded. Joint powers were calculated using a sagittal plane inverse dynamics model, averaged for the initial, middle, and final three-second intervals of the trial, and normalized to initial values.

Relative ankle plantar flexion power was significantly less than all other joint actions at the middle interval. Relative ankle plantar flexion power for the final interval was significantly less than the relative knee flexion and hip extension power. Relative knee extension power was significantly less than relative hip extension power during the final three second interval. Knee flexion power did not differ from relative hip extension power.

Implication. Changes in power were accompanied by a decrease in time spent extending by each joint with the onset of anaerobic fatigue. Because the ankle fatigued more than the hip and knee joints, either peripheral muscle fatigue or changes in motor control strategies were identified as the potential mechanisms for joint-specific fatigue.

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