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DOI: 10.1055/s-2007-965161
© Georg Thieme Verlag KG Stuttgart · New York
Bright Light and Thermoregulatory Responses to Exercise
Publikationsverlauf
accepted after revision February 12, 2007
Publikationsdatum:
13. September 2007 (online)
![](https://www.thieme-connect.de/media/sportsmed/200803/lookinside/thumbnails/10.1055-s-2007-965161-1.jpg)
Abstract
The thermoregulatory responses to morning exercise after exposure to different schedules of bright light were examined. At 07:00 h, six males ran on two occasions in an environmental chamber (temperature = 31.4 ± 1.0 °C, humidity = 66 ± 6 %) for 40 min at 60 % of maximal oxygen uptake. Participants were exposed to bright light (10 000 lux) either between 22:00 - 23:00 h (BTlow) or 06:00 - 07:00 h (BThigh). Otherwise, participants remained in dim light (< 50 lux). It was hypothesized that BTlow attenuates core temperature during morning exercise via the phase-delaying properties of evening bright light and by avoiding bright light in the morning. Evening bright light in BTlow suppressed (p = 0.037) the increase in melatonin compared to dim light (1.1 ± 11.4 vs. 15.2 ± 19.7 pg · ml-1) and delayed (p = 0.034) the core temperature minimum by 1.46 ± 1.24 h. Core temperature was 0.20 ± 0.17 °C lower in BTlow compared to BThigh during the hour before exercise (p = 0.036), with evidence (p = 0.075) that this difference was maintained during exercise. Conversely, mean skin temperature was 1.0 ± 1.7 °C higher during the first 10 min of exercise in BTlow than in BThigh (p = 0.030). There was evidence that the increase in perceived exertion was attenuated in BTlow (p = 0.056). A chronobiologically-based light schedule can lower core temperature before and during morning exercise in hot conditions.
Key words
body temperature - physical activity - circadian rhythm - melatonin
References
- 1 Aizawa S, Tokura H. Influence of bright light exposure for several hours during the daytime on cutaneous vasodilation and local sweating induced by exercise heat load. Eur J Appl Physiol. 1998; 78 303-307
- 2 Aldemir H, Atkinson G, Cable T, Edwards B, Waterhouse J, Reilly T. A comparison of the immediate effects of moderate exercise in the early morning and late afternoon on core temperature and cutaneous thermoregulatory mechanisms. Chronobiol Int. 2000; 17 197-207
- 3 Atkinson G. Analysis of repeated measurements in physical therapy research. Phys Ther Sport. 2001; 2 194-208
- 4 Atkinson G. Analysis of repeated measurements in physical therapy research: multiple comparisons amongst level means and multifactorial designs. Phys Ther Sport. 2002; 3 191-203
- 5 Atkinson G, Drust B, Reilly T, Waterhouse J. The relevance of melatonin to sports medicine and science. Sports Med. 2003; 33 809-831
- 6 Atkinson G, Jones H, Edwards B, Reilly T, Waterhouse J. Effects of daytime ingestion of melatonin on short-term athletic performance. Ergonomics. 2005; 48 1512-1522
- 7 Atkinson G, Holder A, Robertson C, Gant N, Drust B, Reilly T, Waterhouse J. Effects of melatonin on the thermoregulatory responses to intermittent exercise. J Pineal Res. 2005 b; 39 353-359
- 8 Badia P, Myers B, Boecker M, Culpepper J, Harsh J R. Bright light effects on body temperature, alertness, EEG and behavior. Physiol Behav. 1991; 50 583-588
- 9 Batterham A M, Atkinson G. How big does my sample need to be? A primer on the murky world of sample size estimation. Phys Ther Sport. 2005; 6 153-163
- 10 Sport B BC. Anger at Beijing swimming switch. http://news.bbc.co.uk/sport2/hi/other_sports/6086814. stm, Date visited; November 7 2006
- 11 Booth J, Marino F, Ward J. Improved running performance in hot humid conditions following whole body pre-cooling. Med Sci Sports Exerc. 1997; 29 943-949
- 12 Borg G AV. Psychological bases of perceived exertion. Med Sci Sports Exerc. 1982; 14 377-381
- 13 Burgess H J, Sletten T, Savic N, Gilbert S S, Dawson D. Effects of bright light and melatonin on sleep propensity, temperature, and cardiac activity at night. J Appl Physiol. 2001; 91 1214-1222
- 14 Burton A C. Human calorimetry. J Nutr. 1935; 9 261-280
- 15 Cajochen C, Dijk D J, Borbely A A. Dynamics of EEG slow-wave activity and core body temperature in human sleep after exposure to bright light. Sleep. 1992; 15 337-343
- 16 Cajochen C, Krauchi K, Wirz-Justice A. Role of melatonin in the regulation of human circadian rhythms and sleep. J Neuroendocrin. 2003; 15 432-437
- 17 Gant N, Williams C. The validity and reliability of intestinal temperature during intermittent running. J Sports Sci. 2005; 23 1190
- 18 González-Alonso J, Teller C, Andersen S L. et al . Influence of body temperature on the development of fatigue during prolonged exercise in the heat. J Appl Physiol. 1999; 86 1032-1039
- 19 Krauchi K, Cajochen C, Damilenko K V, Wirz-Justice A. The hypothermic effect of late evening melatonin does not block the phase delay induced by concurrent bright light in human subjects. Neurosci Let. 1997; 232 57-61
- 20 Kubota T, Uchiyama M, Suzuki H, Shibui K, Kim K, Tan X, Tagaya H, Okawa M, Inoue S. Effects of nocturnal bright light on saliva melatonin, core body temperature and sleep propensity rhythms in human subjects. Neurosci Res. 2001; 42 115-122
- 21 Ludbrook J. Multiple comparison procedures updated. Clin Exp Pharmacol Physiol. 1998; 25 1032-1037
- 22 McLellan T M, Gannon G A, Zamecnik J, Brown G M. Low doses of melatonin and diurnal effect on thermoregulation and tolerance to uncompensable heat stress. J Appl Physiol. 1999; 87 308-316
- 23 McLellan T M, Smith I F, Gannon G A, Zamecnik J. Melatonin has no effect on tolerance to uncompensable heat stress in man. Eur J Appl Physiol. 2000; 83 336-343
- 24 O'Brien P M, O'Connor P J. Effect of bright light on cycling performance. Med Sci Sports Exerc. 2000; 32 439-447
- 25 Ramanathan N. A new weighting system for mean surface temperature of the human body. J Appl Physiol. 1964; 19 531-533
- 26 Saunders A G, Dugas J P, Tucker R, Lambert M I, Noakes T D. The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environment. Acta Physiol Scand. 2005; 183 241-255
- 27 Waterhouse J, Drust B, Weinert D. et al . The circadian rhythm of core temperature: origin and some implications for exercise performance. Chronobiol Int. 2005; 22 205-223
- 28 Youngstedt S D, Kripke D F, Elliott J A. Circadian phase-delaying effects of bright light alone and combined with exercise in humans. Am J Physiol. 2002; 282 R259-R266
- 29 Zhang P, Tokura H. Thermoregulatory responses in humans during exercise after exposure to two different light intensities. Eur J Appl Physiol. 1999; 79 285-289
Prof. Greg Atkinson
Research Institute for Sport and Exercise Sciences
Liverpool John Moores University
Henry Cotton Campus
Webster Street
L3 2ET Liverpool
United Kingdom
Telefon: + 15 12 31 42 49
Fax: + 15 12 31 43 53
eMail: G.atkinson@ljmu.ac.uk