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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Review article
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CIRCADIAN RHYTHMS IN EXERCISE PERFORMANCE: IMPLICATIONS FOR HORMONAL AND MUSCULAR ADAPTATION |
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Weipeng Teo1  ,
Michael J. Newton1 and Michael R. McGuigan2,3 |
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1School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, 2New Zealand Academy of Sport North Island, Auckland, New Zealand, 3Sport Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand |
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© Journal of Sports Science and Medicine (2011) 10, 600 - 606 |
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| ABSTRACT | |||
| Almost all physiological and biochemical processes within the
human body follow a circadian rhythm (CR). In humans, the suprachiasmatic
nucleus regulates sleep- wake cycle and other daily biorhythms in line with
solar time. Due to such daily physiological fluctuations, several investigations
on neuromuscular performance have reported a distinct CR during exercise.
Generally, peak performances have been found to occur in the early evening,
at approximately the peak of core body temperature. The increase in core
body temperature has been found to increase energy metabolism, improve muscle
compliance and facilitate actin-myosin crossbridging. In addition, steroidal
hormones such as testosterone (T) and cortisol (C) also display a clear
CR. The role of T within the body is to maintain anabolism through the process
of protein synthesis. By contrast, C plays a catabolic function and is involved
in the response of stress. Due to the anabolic and catabolic nature of both
T and C, it has been postulated that a causal relationship may exist between
the CR of T and C and muscular performance. This review will therefore discuss
the effects of CR on physical performance and its implications for training.
Furthermore, this review will examine the impact of muscular performance
on CR in hormonal responses and whether could variations in T and C be potentially
beneficial for muscular adaptation. Key words: Diurnal variation, steroidal hormones, neuromuscular adaptation. |
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