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The effect of cadence on the rate of neuromuscular fatigue and the slow component of oxygen uptake in cyclists during heavy exercise

University of British Columbia

This study was designed first to replicate previously published data which examined the effect of cadence on the rate of neuromuscular fatigue of the vastus lateralis muscle in cyclists during heavy exercise and how neuromuscular fatigue was incorporated in the selection of preferred cadence in cyclists. It was the intention of this study to expand previous work and include the examination of other lower limb musculature and detemine a global measure of neuromuscular fatigue for each cadence selected. In addition, the present study sought to assess the affect of cadence on the slow component of oxygen uptake (VO₂ SC) and attempt to establish a relationship between this slow component and a global measure of neuromuscular fatigue. Twelve cyclists performed four sessions of cycling exercise at a power output corresponding to their individual ventilatory thresholds (VT). Each criterion exercise session was performed at a different cadence, ranging from 55 to 100 RPM in 15 RPM steps. A measure of the rate of neuromuscular fatigue was calculated using both a previously published and a novel methodology. Neuromuscular fatigue was evaluated in vastus lateralis, soleus, gastrocnemius, biceps femoris, and gluteus maximus; a global representation was calculated as the sum of the rates of neuromuscular fatigue from all muscle groups. No level of neuromuscular fatigue was observed during the criterion exercise for any of the cadence conditions. There was no relationship between a global representation of neuromuscular fatigue and cadence. The VO₂ SC displayed a significant quadratic trend (p < 0.05) over the range of cadences, with a calculated minimum value at 80.8 RPM. No relationship between neuromuscular fatigue and the VO₂ SC was established, suggesting a different mechanistic basis for these two variables. These data suggested that cyclists do not use a measure of neuromuscular fatigue in the selection of preferred cadence at power outputs corresponding to VT. The cadence minimizing the VO₂ SC did not match the cyclists' preferred cadence, however did corresponded to the pedal frequency previously shown to maximize the efficiency of Type I muscle fibers.

Thesis/Dissertation

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2009-06-16

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http://hdl.handle.net/2429/9274

Human Kinetics

University of British Columbia

UBCV

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