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Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations.
J Sci Med Sport 2019; 22(1):117-122JS

Abstract

OBJECTIVES

To determine if intermittent exercise-heat exposures (IHE) every fifth day sustain heat acclimation (HA) adaptations 25 days after initial HA.

DESIGN

Randomized control trial.

METHODS

Sixteen non-heat acclimatized men heat acclimated during 10-11 days of exercise in the heat (40°C, 40% RH). A heat stress test (120min, 45% V˙O2peak) before (Pre HA) and after HA (Post HA) in similar hot conditions assessed HA status. Pair-matched participants were randomized into a control group (CON; n=7) that exercised in a temperate environment (24°C, 21%RH) or IHE group (n=9) that exercised in a hot environment (40°C, 40%RH) every fifth day for 25 days following HA (+25d) with out-of-laboratory exercise intensity and duration recorded. Both groups completed +25d in the hot condition.

RESULTS

Both groups heat acclimated similarly (p>0.05) evidenced by lower heart rate (HR), thermoregulatory, physiological, and perceptual responses (perceived exertion, fatigue, thermal sensation) Pre HA vs. Post HA (p≤0.05). At +25d, post-exercise HR (p=0.01) and physiological strain index (p<0.05) but neither Tre (p=0.18) nor sweat rate (p=0.44) were lower in IHE vs. CON. In IHE only, post-exercise Tre and perceptual responses at Post HA and +25d were lower than Pre HA (p≤0.01). +25d post-exercise epinephrine was higher in CON vs. IHE (p=0.04). Exercise intensity during out-of-lab exercise and +25d post-exercise HR were correlated (r=-0.89, p=0.02) in IHE.

CONCLUSIONS

Exercise-heat exposures every fifth day for 25 days and regular intense physical activity after HA sustained HR and Tre adaptations and reduced perceptual and physiological strain during exercise-heat stress ∼1 month later.

Authors+Show Affiliations

Central California Sports Sciences Institute, Department of Kinesiology, California State University, United States; Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States. Electronic address: lukepryor@csufresno.edu.Central California Sports Sciences Institute, Department of Kinesiology, California State University, United States; Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States.Department of Human Sciences, The Ohio State University, United States.

Pub Type(s)

Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

30554611

Citation

Pryor, J Luke, et al. "Intermittent Exercise-heat Exposures and Intense Physical Activity Sustain Heat Acclimation Adaptations." Journal of Science and Medicine in Sport, vol. 22, no. 1, 2019, pp. 117-122.
Pryor JL, Pryor RR, Vandermark LW, et al. Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations. J Sci Med Sport. 2019;22(1):117-122.
Pryor, J. L., Pryor, R. R., Vandermark, L. W., Adams, E. L., VanScoy, R. M., Casa, D. J., ... Maresh, C. M. (2019). Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations. Journal of Science and Medicine in Sport, 22(1), pp. 117-122. doi:10.1016/j.jsams.2018.06.009.
Pryor JL, et al. Intermittent Exercise-heat Exposures and Intense Physical Activity Sustain Heat Acclimation Adaptations. J Sci Med Sport. 2019;22(1):117-122. PubMed PMID: 30554611.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Intermittent exercise-heat exposures and intense physical activity sustain heat acclimation adaptations. AU - Pryor,J Luke, AU - Pryor,Riana R, AU - Vandermark,Lesley W, AU - Adams,Elizabeth L, AU - VanScoy,Rachel M, AU - Casa,Douglas J, AU - Armstrong,Larry E, AU - Lee,Elaine C, AU - DiStefano,Lindsay J, AU - Anderson,Jeffrey M, AU - Maresh,Carl M, Y1 - 2018/06/19/ PY - 2017/12/30/received PY - 2018/05/02/revised PY - 2018/06/12/accepted PY - 2018/12/18/entrez PY - 2018/12/18/pubmed PY - 2019/1/15/medline KW - Decay KW - Exertional heat illness KW - Heat acclimatization KW - Induction KW - Thermoregulation SP - 117 EP - 122 JF - Journal of science and medicine in sport JO - J Sci Med Sport VL - 22 IS - 1 N2 - OBJECTIVES: To determine if intermittent exercise-heat exposures (IHE) every fifth day sustain heat acclimation (HA) adaptations 25 days after initial HA. DESIGN: Randomized control trial. METHODS: Sixteen non-heat acclimatized men heat acclimated during 10-11 days of exercise in the heat (40°C, 40% RH). A heat stress test (120min, 45% V˙O2peak) before (Pre HA) and after HA (Post HA) in similar hot conditions assessed HA status. Pair-matched participants were randomized into a control group (CON; n=7) that exercised in a temperate environment (24°C, 21%RH) or IHE group (n=9) that exercised in a hot environment (40°C, 40%RH) every fifth day for 25 days following HA (+25d) with out-of-laboratory exercise intensity and duration recorded. Both groups completed +25d in the hot condition. RESULTS: Both groups heat acclimated similarly (p>0.05) evidenced by lower heart rate (HR), thermoregulatory, physiological, and perceptual responses (perceived exertion, fatigue, thermal sensation) Pre HA vs. Post HA (p≤0.05). At +25d, post-exercise HR (p=0.01) and physiological strain index (p<0.05) but neither Tre (p=0.18) nor sweat rate (p=0.44) were lower in IHE vs. CON. In IHE only, post-exercise Tre and perceptual responses at Post HA and +25d were lower than Pre HA (p≤0.01). +25d post-exercise epinephrine was higher in CON vs. IHE (p=0.04). Exercise intensity during out-of-lab exercise and +25d post-exercise HR were correlated (r=-0.89, p=0.02) in IHE. CONCLUSIONS: Exercise-heat exposures every fifth day for 25 days and regular intense physical activity after HA sustained HR and Tre adaptations and reduced perceptual and physiological strain during exercise-heat stress ∼1 month later. SN - 1878-1861 UR - https://www.unboundmedicine.com/medline/citation/30554611/Intermittent_exercise_heat_exposures_and_intense_physical_activity_sustain_heat_acclimation_adaptations_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1440-2440(18)30260-3 DB - PRIME DP - Unbound Medicine ER -