TY - JOUR
T1 - Age Modulates Physiological Responses during Fan Use under Extreme Heat and Humidity
AU - Gagnon, Daniel
AU - Romero, Steven A.A.
AU - Cramer, Matthew N.N.
AU - Kouda, Ken
AU - Poh, Paula YS
AU - Ngo, Hai
AU - Jay, Ollie
AU - Crandall, Craig G.G.
N1 - Funding Information:
This study was supported by the National Institutes of Health (GM-068865) and Department of Defense (W81XWH-12-1-0152). D. G. was supported by a Postdoctoral Fellowship from the Natural Sciences and Engineering Research Council of Canada. The authors thank Naomi Kennedy and Amy Adams for their contributions to the study. The authors would also like to thank Dr. John R. Halliwill for the development and use of the DUC2 software. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation.
Publisher Copyright:
© 2017 by the American College of Sports Medicine.
PY - 2017/11/1
Y1 - 2017/11/1
N2 - 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.
AB - 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.
KW - CARDIOVASCULAR
KW - CORE TEMPERATURE
KW - HEART RATE
KW - HEAT WAVE
KW - SWEAT
KW - VASODILATION
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U2 - 10.1249/MSS.0000000000001348
DO - 10.1249/MSS.0000000000001348
M3 - Article
C2 - 28609330
AN - SCOPUS:85020719873
SN - 0195-9131
VL - 49
SP - 2333
EP - 2342
JO - Medicine and science in sports and exercise
JF - Medicine and science in sports and exercise
IS - 11
ER -