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Fitness-related differences in the rate of whole-body evaporative heat loss in exercising men are heat-load dependent.

التفاصيل البيبلوغرافية
العنوان: Fitness-related differences in the rate of whole-body evaporative heat loss in exercising men are heat-load dependent.
المؤلفون: Lamarche DT; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada., Notley SR; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada., Louie JC; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada., Poirier MP; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada., Kenny GP; Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada.
المصدر: Experimental physiology [Exp Physiol] 2018 Jan 01; Vol. 103 (1), pp. 101-110. Date of Electronic Publication: 2017 Nov 22.
نوع المنشور: Journal Article; Research Support, Non-U.S. Gov't
اللغة: English
بيانات الدورية: Publisher: Wiley-Blackwell Country of Publication: England NLM ID: 9002940 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1469-445X (Electronic) Linking ISSN: 09580670 NLM ISO Abbreviation: Exp Physiol Subsets: MEDLINE
أسماء مطبوعة: Publication: Cambridge, Eng : Wiley-Blackwell
Original Publication: Cambridge ; New York, NY, USA : Published for the Physiological Society by Cambridge University Press, c1990-
مواضيع طبية MeSH: Hot Temperature*, Body Temperature/*physiology , Body Temperature Regulation/*physiology , Exercise/*physiology , Heart Rate/*physiology , Physical Fitness/*physiology, Adolescent ; Adult ; Calorimetry/methods ; Humans ; Male ; Thermogenesis/physiology ; Young Adult
مستخلص: New Findings: What is the central question of this study? Aerobic fitness modulates heat loss, but the heat-load threshold at which fitness-related differences in heat loss occur in young healthy men remains unclear. What is the main finding and its importance? We demonstrate using direct calorimetry that aerobic fitness modulates heat loss in a heat-load-dependent manner, with fitness-related differences occurring between young men who have low and high fitness when the heat load is ∼≥500 W. Although aerobic fitness has been known for some time to modulate heat loss, our findings define the precise heat-load threshold at which fitness-related differences occur. The effect of aerobic fitness (defined as rate of peak oxygen consumption) on heat loss during exercise is thought to be related to the level of heat stress. However, it remains unclear at what combined exercise and environmental (net) heat-load threshold these fitness-related differences occur. To identify this, we assessed whole-body heat exchange (dry and evaporative) by direct calorimetry in young (22 ± 3 years) men matched for physical characteristics with low (Low-fit; 39.8 ± 2.5 ml O 2  kg -1  min -1 ), moderate (Mod-fit; 50.9 ± 1.2 ml O 2  kg -1  min -1 ) and high aerobic fitness (High-fit; 62.0 ± 4.4 ml O 2  kg -1  min -1 ; each n = 8), during three 30 min bouts of cycling in dry heat (40°C, 12% relative humidity) at increasing rates of metabolic heat production of 300 (Ex1), 400 (Ex2) and 500 W (Ex3), each followed by a 15 min recovery period. Each group was exposed to a similar net heat load (metabolic plus ∼100 W dry heat gain; P = 0.83) during each exercise bout [∼400 (Ex1), ∼500 (Ex2) and ∼600 W (Ex3); P < 0.01]. Although evaporative heat loss was similar between groups during Ex1 (P = 0.33), evaporative heat loss was greater in the High-fit (Ex2, 466 ± 21 W; Ex3, 557 ± 26 W) compared with the Low-fit group (Ex2, 439 ± 22 W; Ex3, 511 ± 20 W) during Ex2 and Ex3 (P ≤ 0.03). Conversely, evaporative heat loss for the Mod-fit group did not differ from either the High-fit or Low-fit group during all exercise bouts (P ≥ 0.09). We demonstrate that aerobic fitness modulates heat loss in a heat-load-dependent manner, such that young, highly fit men display greater heat-loss capacity only at heat loads ∼≥500 W compared with their lesser trained counterparts.
(© 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.)
فهرسة مساهمة: Keywords: aerobic fitness; heat loss; thermoregulation
تواريخ الأحداث: Date Created: 20171021 Date Completed: 20190109 Latest Revision: 20190109
رمز التحديث: 20231215
DOI: 10.1113/EP086637
PMID: 29052285
قاعدة البيانات: MEDLINE
الوصف
تدمد:1469-445X
DOI:10.1113/EP086637