Elmer, S. J., Marshall, C. S., Amann, M., & Martin, J. C. (2013). Neuromuscular fatigue, reserve, and recovery following exhaustive high-intensity endurance exercise. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 764.

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This study evaluated exercise-induced changes in maximum cycling power immediately following exhaustive high-intensity cycling. Cyclists (N = 4) performed maximal isokinetic cycling trials (3-seconds, 90 rpm) before and again 0, 0.25, 0.75, 2.0, 3.3 , 6.6, and 10 minutes after either a isokinetic cycling time-trial (10 minutes, 90 rpm) or isokinetic constant power cycling until task failure (100% of time-trial power, 10.1 minutes, 90 rpm). Fatigue was estimated by comparing exercise-induced changes in maximum cycling power.

Power produced during the time-trial and task-failure trial did not differ. Exercise-induced alterations in maximum cycling power were similar following both tasks and thus, pooled values were reported. When compared to pre-exercise, post-exercise maximum cycling power was reduced by ~38% immediately following both trials. However, at 3.3 minutes post-exercise, maximum cycling power did not differ from pre-exercise. Immediate post-exercise maximum cycling power was more than twice as high as the power produced during the final three seconds of the time-trial as well as the power that elicited task failure.

Implication. Exhaustive high-intensity cycling substantially compromises maximum cycling power. Recovery of this impaired function occurs within a few minutes. Such rapid recovery may be linked to PCr resynthesis. These results highlight the recovery of brief maximal voluntary neuromuscular function and contrast with previous reports of long lasting low-frequency fatigue evaluated via pre- to post-exercise changes in quadriceps potentiated twitch force. Even with considerable fatigue, Ss were able to produce substantially greater power after a time-trial and cycling to exhaustion, thus indicating a “reserve capacity” which has been a recent topic of debate.

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