Neuromuscular function following prolonged intense self-paced exercise in hot climatic conditions

Julien D Périard, Matthew N. Cramer, Phillip G Chapman, Corinne Caillaud, Martin W. Thompson

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Muscle weakness following constant load exercise under heat stress has been associated with hyperthermia-induced central fatigue. However, evidence of central fatigue influencing intense self-paced exercise in the heat is lacking. The purpose of this investigation was to evaluate force production capacity and central nervous system drive in skeletal muscle pre- and post-cycle ergometer exercise in hot and cool conditions. Nine trained male cyclists performed a 20-s maximal voluntary isometric contraction (MVC) prior to (control) and following a 40-km time trial in hot (35°C) and cool (20°C) conditions. MVC force production and voluntary activation of the knee extensors was evaluated via percutaneous tetanic stimulation. In the cool condition, rectal temperature increased to 39.0°C and reached 39.8°C in the heat (P < 0.01). Following exercise in the hot and cool conditions, peak force declined by ~90 and ~99 N, respectively, compared with control (P < 0.01). Mean force decreased by 15% (hot) and 14% (cool) (P < 0.01 vs. control). Voluntary activation during the post-exercise MVC declined to 93.7% (hot) and 93.9% (cool) (P < 0.05 vs. control). The post-exercise decline in voluntary activation represented ~20% of the decrease in mean force production in both conditions. Therefore, the additional increase in rectal temperature did not exacerbate the loss of force production following self-paced exercise in the heat. The impairment in force production indicates that the fatigue exhibited by the quadriceps is mainly of peripheral origin and a consequence of the prolonged contractile activity associated with exercise.

Original languageEnglish
Pages (from-to)1561-9
Number of pages9
JournalEuropean Journal of Applied Physiology
Volume111
Issue number8
DOIs
Publication statusPublished - Aug 2011
Externally publishedYes

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Isometric Contraction
Hot Temperature
Fatigue
Induced Hyperthermia
Temperature
Muscle Weakness
Knee
Skeletal Muscle
Central Nervous System

Cite this

Périard, Julien D ; Cramer, Matthew N. ; Chapman, Phillip G ; Caillaud, Corinne ; Thompson, Martin W. / Neuromuscular function following prolonged intense self-paced exercise in hot climatic conditions. In: European Journal of Applied Physiology. 2011 ; Vol. 111, No. 8. pp. 1561-9.
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Neuromuscular function following prolonged intense self-paced exercise in hot climatic conditions. / Périard, Julien D; Cramer, Matthew N.; Chapman, Phillip G; Caillaud, Corinne; Thompson, Martin W.

In: European Journal of Applied Physiology, Vol. 111, No. 8, 08.2011, p. 1561-9.

Research output: Contribution to journalArticle

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AB - Muscle weakness following constant load exercise under heat stress has been associated with hyperthermia-induced central fatigue. However, evidence of central fatigue influencing intense self-paced exercise in the heat is lacking. The purpose of this investigation was to evaluate force production capacity and central nervous system drive in skeletal muscle pre- and post-cycle ergometer exercise in hot and cool conditions. Nine trained male cyclists performed a 20-s maximal voluntary isometric contraction (MVC) prior to (control) and following a 40-km time trial in hot (35°C) and cool (20°C) conditions. MVC force production and voluntary activation of the knee extensors was evaluated via percutaneous tetanic stimulation. In the cool condition, rectal temperature increased to 39.0°C and reached 39.8°C in the heat (P < 0.01). Following exercise in the hot and cool conditions, peak force declined by ~90 and ~99 N, respectively, compared with control (P < 0.01). Mean force decreased by 15% (hot) and 14% (cool) (P < 0.01 vs. control). Voluntary activation during the post-exercise MVC declined to 93.7% (hot) and 93.9% (cool) (P < 0.05 vs. control). The post-exercise decline in voluntary activation represented ~20% of the decrease in mean force production in both conditions. Therefore, the additional increase in rectal temperature did not exacerbate the loss of force production following self-paced exercise in the heat. The impairment in force production indicates that the fatigue exhibited by the quadriceps is mainly of peripheral origin and a consequence of the prolonged contractile activity associated with exercise.

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KW - Physical Exertion

KW - Time Factors

KW - Journal Article

KW - Randomized Controlled Trial

KW - Research Support, Non-U.S. Gov't

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SN - 1439-6319

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