Effects of 22°C muscle temperature on the rate of recovery of voluntary and evoked contractile properties of the plantar flexor after high intensity exercise

Drinkwater, Eric J. (2001) Effects of 22°C muscle temperature on the rate of recovery of voluntary and evoked contractile properties of the plantar flexor after high intensity exercise. Masters thesis, Memorial University of Newfoundland.

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Abstract

The primary goal of this study was to investigate the interaction effects of 22°C local muscle temperature on the recovery of specific evoked and voluntary contractile properties in intact human plantar flexors at 1-. 5-. and 10-minutes after high intensity, isometric exercise. The secondary goal of this study was to validate previous studies and add to the body of knowledge about the main effects of recovery from fatigue with homeostatic temperature and the main effects of local hypothermia on unfatigued muscle on evoked and voluntary contractile properties in intact human plantar flexors. Twelve subjects were tested for muscle voluntary and evoked contractile properties prior to fatigue (i.e. pre-fatigue), fatigued using intermittent, high-intensity, isometric contraction, and then retested at 1-. 5-. and 10-minutes post-fatigue conditions under localized hypothermic and normothermic conditions. Voluntary properties of the plantar flexor muscles were monitored by measuring the force of a maximal voluntary isometric contraction, as well as muscle activation derived from the interpolated twitch technique (ITT) and integrated electromyographic (iEMG) activity. Evoked contractile properties included the force and temporal characteristics of a maximal twitch and titanic contraction of the plantar flexor muscles. Data were analyzed with a 2-way repeated measures ANOVA for main effects of a) hypothermic and normothermic conditions, b) prefatigue and at post-fatigue intervals, and c) interactions between hypothermic and normothermic pre- and post-fatigue intervals. During recovery from high intensity-intermittent fatigue there was a general augmentation of evoked properties of the plantar flexors with a deceleration and decrease of the force of voluntary properties. Hypothermia had little effect on all but the temporal characteristics of the plantar flexor muscles, which were slowed by cold. The effect of cold on the rate of recovery of the plantar flexor muscles was generally not significant. Thus it may be concluded that local muscle hypothermia does not impair recovery of voluntary and evoked contractile properties of the plantar flexors from high intensity exercise.

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