Repeated-bout exercise in the heat in young athletes: Physiological strain and perceptual responses

Michael F. Bergeron, Melissa D. Laird, Elaina L. Marinik, Joel S. Brenner, Jennifer L Waller

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

A short recovery period between same-day competitions is common practice in organized youth sports. We hypothesized that young athletes will experience an increase in physiological strain and perceptual discomfort during a second identical exercise bout in the heat, with 1 h (21°C) between bouts, even with ample hydration. Twenty-four athletes (6 boys and 6 girls: 12-13 yr old, 47.7 ± 8.3 kg; 6 boys and 6 girls: 16-17 yr old, 61.0 ± 8.6 kg) completed two 80-min intermittent exercise bouts (treadmill 60%, cycle 40% peak oxygen uptake) in the heat (33°C, 48.9 ± 6.1% relative humidity). Sweat loss during each bout was similar within each age group (12-13 yr old: bout 1, 943.6 ± 237.1 ml; bout 2, 955.5 ± 250.3 ml; 16-17 yr old: bout 1, 1,382.2 ± 480.7 ml; bout 2, 1,373.1 ± 472.2 ml). Area under the curve (AUC) was not statistically different (P > 0.05) between bouts for core body temperature (12-13 yr old: bout 1 peak, 38.6 ± 0.4°C; bout 2, 38.4 ± 0.2°C; 16-17 yr old: bout 1 peak, 38.8 ± 0.7°C; bout 2, 38.7 ± 0.6° C), physiological strain index (12-13 yr old: bout 1 peak, 7.9 ± 0.9; bout 2, 7.5 ± 0.7; 16-17 yr old: bout 1 peak, 8.1 ± 1.5; bout 2, 7.9 ± 1.4), or thermal sensation for any age/sex subgroup or for all subjects combined. However, rating of perceived exertion AUC and peak were higher (P = 0.0090 and 0.0004, respectively) during bout 2 in the older age group. Notably, four subjects experienced consistently higher responses throughout bout 2. With these healthy, fit, young athletes, 1 h of complete rest, cool down, and rehydration following 80 min of strenuous exercise in the heat was generally effective in eliminating any apparent carryover effects that would have resulted in greater thermal and cardiovascular strain during a subsequent identical exercise bout.

Original languageEnglish (US)
Pages (from-to)476-485
Number of pages10
JournalJournal of Applied Physiology
Volume106
Issue number2
DOIs
StatePublished - Feb 1 2009

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Athletes
Hot Temperature
Exercise
Area Under Curve
Age Groups
Sweat
Fluid Therapy
Humidity
Body Temperature
Oxygen

Keywords

  • Hydration
  • Recovery
  • Risk management
  • Thermoregulation
  • Youth sports

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Repeated-bout exercise in the heat in young athletes : Physiological strain and perceptual responses. / Bergeron, Michael F.; Laird, Melissa D.; Marinik, Elaina L.; Brenner, Joel S.; Waller, Jennifer L.

In: Journal of Applied Physiology, Vol. 106, No. 2, 01.02.2009, p. 476-485.

Research output: Contribution to journalArticle

Bergeron, Michael F. ; Laird, Melissa D. ; Marinik, Elaina L. ; Brenner, Joel S. ; Waller, Jennifer L. / Repeated-bout exercise in the heat in young athletes : Physiological strain and perceptual responses. In: Journal of Applied Physiology. 2009 ; Vol. 106, No. 2. pp. 476-485.
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