Age Modulates Physiological Responses during Fan Use under Extreme Heat and Humidity

Daniel Gagnon, Steven A. Romero, Matthew N. Cramer, Ken Kouda, Paula Y.S. Poh, Hai Ngo, Ollie Jay, Craig G. Crandall

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Purpose We examined the effect of electric fan use on cardiovascular and thermoregulatory responses of nine young (26 ± 3 yr) and nine aged (68 ± 4 yr) adults exposed to extreme heat and humidity. Methods While resting at a temperature of 42°C, relative humidity increased from 30% to 70% in 2% increments every 5 min. On randomized days, the protocol was repeated without or with fan use. HR, core (Tcore) and mean skin (Tsk) temperatures were measured continuously. Whole-body sweat loss was measured from changes in nude body weight. Other measures of cardiovascular (cardiac output), thermoregulatory (local cutaneous and forearm vascular conductance, local sweat rate), and perceptual (thermal and thirst sensations) responses were also examined. Results When averaged over the entire protocol, fan use resulted in a small reduction of HR (-2 bpm, 95% confidence interval [CI], -8 to 3), and slightly greater Tcore (+0.05°C; 95% CI, -0.13 to 0.23) and Tsk (+0.03°C; 95% CI, -0.36 to 0.42) in young adults. In contrast, fan use resulted in greater HR (+5 bpm; 95% CI, 0-10), Tcore (+0.20°C; 95% CI, 0.00-0.41), and Tsk (+0.47°C; 95% CI, 0.18-0.76) in aged adults. A greater whole-body sweat loss during fan use was observed in young (+0.2 kg; 95% CI, -0.2 to 0.6) but not aged (0.0 kg; 95% CI, -0.2 to 0.2) adults. Greater local sweat rate and cutaneous vascular conductance were observed with fan use in aged adults. Other measures of cardiovascular, thermoregulatory, and perceptual responses were unaffected by fan use in both groups. Conclusions During extreme heat and humidity, fan use elevates physiological strain in aged, but not young, adults.

Original languageEnglish
Pages (from-to)2333-2342
Number of pages10
JournalMedicine and Science in Sports and Exercise
Volume49
Issue number11
DOIs
StatePublished - 1 Nov 2017

Keywords

  • CARDIOVASCULAR
  • CORE TEMPERATURE
  • HEART RATE
  • HEAT WAVE
  • SWEAT
  • VASODILATION

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