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Eur J Appl Physiol. 2013 Jan;113(1):183-90. doi: 10.1007/s00421-012-2428-3. Epub 2012 May 29.

Heat stress attenuates the increase in arterial blood pressure during isometric handgrip exercise.

Author information

1
Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University, Room 367, Montpetit Hall, Ottawa, ON K1N 6N5, Canada.

Abstract

The purpose of this study was to examine arterial blood pressure responses during isometric handgrip (IHG) exercise performed at increasing levels of heat stress. Ten male subjects performed 1 min of IHG exercise at 60 % of maximal voluntary contraction under no heat stress (NHS), moderate heat stress [MHS, 0.6 °C increase in esophageal temperature (T (es))] and high heat stress (HHS, 1.4 °C increase in T (es)). For all conditions, IHG exercise significantly elevated mean arterial pressure (MAP) (NHS: 124 ± 6 vs. 90 ± 4 mmHg, MHS: 112 ± 6 vs. 89 ± 6 mmHg, HHS: 107 ± 7 vs. 91 ± 5 mmHg, P ≤ 0.05) and cardiac output (CO) (NHS: 9.0 ± 1.5 vs. 6.1 ± 0.6 L/min, MHS: 9.8 ± 1.8 vs. 7.6 ± 1.3 L/min, HHS: 10.0 ± 2.0 vs. 8.5 ± 1.9 L/min, P ≤ 0.05) relative to baseline, whereas no differences in total peripheral resistance (TPR) were observed (P > 0.05). However, the relative increases in MAP and CO were significantly reduced during MHS (MAP: 23 ± 6 mmHg, CO: 2.1 ± 0.9 L/min) and HHS (MAP: 16 ± 7 mmHg, CO: 1.5 ± 0.8 L/min) compared to NHS (34 ± 5 mmHg, CO: 2.9 ± 1.1 L/min, P ≤ 0.05). Furthermore, these elevations were significantly attenuated during HHS compared to MHS (P ≤ 0.05). Our findings show that heat stress attenuates the increase in arterial blood pressure during isometric handgrip exercise and this attenuation is cardiac output dependent, since TPR did not change during exercise for all heat stress conditions.

PMID:
22644569
DOI:
10.1007/s00421-012-2428-3
[Indexed for MEDLINE]

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