Int J Sports Med 2012; 33(03): 211-217
DOI: 10.1055/s-0031-1295444
Training & Testing
© Georg Thieme Verlag KG Stuttgart · New York

Run Performance of Middle-Aged and Young Adult Runners in the Heat

J. de Paula Viveiros
1   Federal Center of Technological Education of Minas Gerais, Department of Physical Education and Sport, Belo Horizonte, Brazil
,
F. T. Amorim
2   Federal University of the Valleys of the Jequitinhonha and Mucuri, Department of Health Sciences, Diamantina, Brazil
,
M. N. M. Alves
3   Norwegian University of Science and Technology, Institutt for sirkulasjon og bildediagnostikk, Trondheim, Norway
,
R. L. F. Passos
4   Federal University of Minas Gerais, Department of Physical Education, Belo Horizonte, Brazil
,
F. Meyer
5   Federal University of Rio Grande do Sul, Department of Sport, Porto Alegre, Brazil
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accepted after revision 11. Oktober 2011

Publikationsdatum:
08. Dezember 2011 (online)

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Abstract

The aging process may impair exercise tolerance in the heat. It is not clear whether this impairment is partly due to a reduction in aerobic capacity. To compare the exercise performance and thermoregulatory responses of middle-aged and young adults with similar aerobic capacities and training statuses, 7 middle-aged (54±2 years; 58±4 ml·kg − 1·min − 1) and 7 young (28±1 years; 61±5 ml·kg − 1·min − 1) male competitive endurance runners underwent 2 10-km self-paced and 2 fixed-workload (90% of race speed) runs until fatigue on a treadmill in hot (40°C) and moderate (20°C) environments on separate days. The runners’ total time, average speed, rectal temperature, heat storage rate, physiological strain index, sweat rate, sweat sensitivity, number of heat-activated sweat glands and sweat rate per sweat gland were measured or calculated. Body fat, body surface area, body surface area per body mass, training volume and VO2max were similar between the 2 groups. No differences were observed in total time (59±3; 49±3; 27±2; 54±5 min in the middle-aged and 60±2; 49±3; 27±2; 51±4 min in the young group), average speed, rectal temperature, heat storage rate, physiological strain index, sweat rate (17±7; 15±3; 23±7; 13±2 g.m − 2.min − 1 in the middle-aged and 20±5; 14±4; 22±5; 15±4 g.m − 2.min − 1 in the young group) or sweat sensitivity between age groups (p>0.05) in any trial. The number of heat-activated sweat glands (88±14; 80±18; 90±16; 66±14 cm − 2 in the middle-aged and 43±10; 32±10; 37±11; 31±11 cm − 2 in the young group) was higher, and the sweat rate per sweat gland was smaller, in the middle-aged than the young group (p<0.05) in all of the trials. We conclude that running performance and body thermoregulation are similar between young and middle-aged runners with similar aerobic capacities and training statuses under hot and moderate conditions in self-paced and fixed-intensity runs. The decrease observed in the sweat rate per sweat gland in middle-aged men was compensated for by a higher number of heat-activated sweat glands.