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CURRENT ISSUETHE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS

A Journal on Applied Physiology, Biomechanics, Preventive Medicine,
Sports Medicine and Traumatology, Sports Psychology

Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
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ISSN 0022-4707

Online ISSN 1827-1928

 

The Journal of Sports Medicine and Physical Fitness 2003 September;43(3):386-92

EPIDEMIOLOGY AND CLINICAL MEDICINE 

    Original articles

Individual differences in self-reported heat tolerance. Is there a link to the cardiocirculatory, thermoregulatory and hormonal response to endurance exercise in heat?

Niess A. M. 1, Feherenbach E. 2, Roecker K. 1, Lehmann R. 3, Opavsky L. 4, Dickhuth H. H. 1

1 Cen­ter for Inter­nal Med­i­cine Depart­ment of Pre­ven­tion, Reha­bil­i­ta­tion and ­Sports Med­i­cine Frei­burg Uni­ver­sity Hos­pi­tal, Ger­ma­ny
2 Depart­ment of Trans­fu­sion Med­i­cine Uni­ver­sity of Tueb­ing­en, Tueb­ing­en, Ger­ma­ny
3 Medical Clinic and Polyclinic Depart­ment of Endo­cri­nol­o­gy and Metab­olism Uni­ver­sity of Tueb­ing­en, Tueb­ing­en, Ger­ma­ny
4 Depart­ment of ­Sports Med­i­cine Uni­ver­sity of Tueb­ing­en, Tueb­ing­en, Ger­ma­ny

Aim. Tol­er­ance to exer­cise in ­heat exhib­its ­great inter­in­di­vid­u­al var­i­abil­ity. We ques­tioned wheth­er indi­vid­u­al dif­fer­enc­es in ­self-report­ed ­heat tol­er­ance with­in a ­group of endu­rance ­trained ath­letes are ­linked to the car­di­o­cir­cu­la­to­ry, ther­mo­reg­u­la­to­ry and hor­mo­nal ­response to endu­rance exer­cise in ­heat.
Meth­ods. ­Using a rat­ing ­scale to ­assess the indi­vid­u­al ­degree of tol­er­ance to exer­cise in ­heat we allo­cat­ed 12 non-­heat-accli­mat­ed ­trained run­ners ­into two ­groups of 5 high­ly ­heat tol­er­ant (HHT) and 7 ­less ­heat tol­er­ant (LHT) ath­letes. ­Both ­groups per­formed a 60-min tread­mill run (veloc­ity 90% of indi­vid­u­al anaer­o­bic thresh­old, ­room tem­per­a­ture and humid­ity 28°C and 50%, respec­tive­ly).
­Results. Sweat­ing ­rate did not dif­fer ­between HHT (­mean ± SEM: 0.44±0.02) and LHT (0.40±0.02 ml·kg-1·min-1). Com­pared to LHT, exer­cise-­induced ris­es in ­core tem­per­a­ture (39.3±0.2/40.0±0.2°C), ­heart ­rate, plas­ma nor­epi­neph­rine and cor­ti­sol ­were sig­nif­i­cant­ly low­er in HHT, ­while epi­neph­rine did not exhib­it dif­fer­enc­es ­between the ­groups. In con­trast, ­response of ­human ­growth hor­mone (hGH) was sig­nif­i­cant­ly ­more pro­nounced in HHT.
Con­clu­sion. Our ­initial ­results, ­obtained in a ­small ­group of endu­rance-­trained run­ners, ­show ­that ­self-report­ed tol­er­ance to exer­cise in ­heat is asso­ciat­ed ­with an atten­u­at­ed ­rise in ­body ­core tem­per­a­ture dur­ing pro­longed exer­cise ­under ele­vat­ed ambi­ent tem­per­a­tures. ­This find­ing in ­heat tol­er­ant ath­letes is par­alleled by a low­er ­stress ­response as reflect­ed by low­er ris­es in ­heart ­rate and ­stress hor­mones ­such as nor­epi­neph­rine and cor­ti­sol. The func­tion­al sig­nif­i­cance (i.e. ­with ­respect to sweat­ing func­tion) of the ­more pro­nounced ­response of hGH in ­heat tol­er­ant ath­letes war­rants fur­ther ­research.

language: English


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