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Determinants of endurance exercise capacity in the heat in prepubertal boys.
Int J Sports Med 2007; 28(1):26-32IJ

Abstract

The goal of this study was to identify factors which limit exercise endurance in hot ambient conditions in prepubertal boys. Eight healthy non-acclimatized, highly physically active prepubertal boys performed steady load cycling at approximately 65 % peak VO (2) to exhaustion in both cool (19.6 +/- 0.6 degrees C, 66.4 +/- 11.0 % relative humidity) and hot (31.0 +/- 0.3 degrees C, 56.9 +/- 2.0 % relative humidity) environmental conditions. Cardiac output, oxygen uptake, rectal temperature (T (re)), rating of perceived exertion (RPE), blood pressure, and calculated arterial venous oxygen difference were obtained serially in each testing session, and percent dehydration was calculated from body weight loss. Endurance time was significantly shorter in the hot condition (29.30 +/- 6.19 minutes versus 41.38 +/- 6.30 minutes in the cool room). No significant differences in circulatory markers or hydration status were observed either during testing or between cycling thermal conditions. Rate of rise of T (re) was greater during exercise in the heat, but no significant difference in T (re) between conditions was observed at exhaustion. Mean values of RPE were consistently greater during exercise in the heat, but these differences did not reach statistical significance. These findings support the concept that rises in core temperature and/or brain perception (RPE) rather than circulatory insufficiency may be the critical factors defining limits to exercise in the heat.

Authors+Show Affiliations

Department of Pediatrics, Baystate Medical Center, Springfield, MA 01106, USA. thomas.rowland@bhs.orgNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17213963

Citation

Rowland, T, et al. "Determinants of Endurance Exercise Capacity in the Heat in Prepubertal Boys." International Journal of Sports Medicine, vol. 28, no. 1, 2007, pp. 26-32.
Rowland T, Garrison A, Pober D. Determinants of endurance exercise capacity in the heat in prepubertal boys. Int J Sports Med. 2007;28(1):26-32.
Rowland, T., Garrison, A., & Pober, D. (2007). Determinants of endurance exercise capacity in the heat in prepubertal boys. International Journal of Sports Medicine, 28(1), pp. 26-32.
Rowland T, Garrison A, Pober D. Determinants of Endurance Exercise Capacity in the Heat in Prepubertal Boys. Int J Sports Med. 2007;28(1):26-32. PubMed PMID: 17213963.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Determinants of endurance exercise capacity in the heat in prepubertal boys. AU - Rowland,T, AU - Garrison,A, AU - Pober,D, PY - 2007/1/11/pubmed PY - 2007/3/21/medline PY - 2007/1/11/entrez SP - 26 EP - 32 JF - International journal of sports medicine JO - Int J Sports Med VL - 28 IS - 1 N2 - The goal of this study was to identify factors which limit exercise endurance in hot ambient conditions in prepubertal boys. Eight healthy non-acclimatized, highly physically active prepubertal boys performed steady load cycling at approximately 65 % peak VO (2) to exhaustion in both cool (19.6 +/- 0.6 degrees C, 66.4 +/- 11.0 % relative humidity) and hot (31.0 +/- 0.3 degrees C, 56.9 +/- 2.0 % relative humidity) environmental conditions. Cardiac output, oxygen uptake, rectal temperature (T (re)), rating of perceived exertion (RPE), blood pressure, and calculated arterial venous oxygen difference were obtained serially in each testing session, and percent dehydration was calculated from body weight loss. Endurance time was significantly shorter in the hot condition (29.30 +/- 6.19 minutes versus 41.38 +/- 6.30 minutes in the cool room). No significant differences in circulatory markers or hydration status were observed either during testing or between cycling thermal conditions. Rate of rise of T (re) was greater during exercise in the heat, but no significant difference in T (re) between conditions was observed at exhaustion. Mean values of RPE were consistently greater during exercise in the heat, but these differences did not reach statistical significance. These findings support the concept that rises in core temperature and/or brain perception (RPE) rather than circulatory insufficiency may be the critical factors defining limits to exercise in the heat. SN - 0172-4622 UR - https://www.unboundmedicine.com/medline/citation/17213963/Determinants_of_endurance_exercise_capacity_in_the_heat_in_prepubertal_boys_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2006-924142 DB - PRIME DP - Unbound Medicine ER -