J Luke Pryor1, Riana R Pryor2, Lesley W Vandermark3, Elizabeth L Adams3, Rachel M VanScoy3, Douglas J Casa3, Larry E Armstrong3, Elaine C Lee3, Lindsay J DiStefano3, Jeffrey M Anderson3, Carl M Maresh4. 1. 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. 2. Central California Sports Sciences Institute, Department of Kinesiology, California State University, United States; Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States. 3. Korey Stringer Institute, Department of Kinesiology, University of Connecticut, United States. 4. Department of Human Sciences, The Ohio State University, United States.
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.
RCT Entities:
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: Yasuki Sekiguchi; Courteney L Benjamin; Ciara N Manning; Jeb F Struder; Lawrence E Armstrong; Elaine C Lee; Robert A Huggins; Rebecca L Stearns; Lindsay J Distefano; Douglas J Casa Journal: Sports Health Date: 2021-10-27 Impact factor: 4.355
Authors: Oliver R Gibson; Carl A James; Jessica A Mee; Ashley G B Willmott; Gareth Turner; Mark Hayes; Neil S Maxwell Journal: Temperature (Austin) Date: 2019-10-12
Authors: Courteney L Benjamin; Yasuki Sekiguchi; Jeb F Struder; Michael R Szymanski; Ciara N Manning; Andrew J Grundstein; Elaine C Lee; Robert A Huggins; Lawrence E Armstrong; Douglas J Casa Journal: Int J Environ Res Public Health Date: 2021-04-20 Impact factor: 3.390
Authors: Margaret C Morrissey; Douglas J Casa; Gabrielle J Brewer; William M Adams; Yuri Hosokawa; Courteney L Benjamin; Andrew J Grundstein; David Hostler; Brendon P McDermott; Meredith L McQuerry; Rebecca L Stearns; Erica M Filep; David W DeGroot; Juley Fulcher; Andreas D Flouris; Robert A Huggins; Brenda L Jacklitsch; John F Jardine; Rebecca M Lopez; Ronda B McCarthy; Yannis Pitisladis; Riana R Pryor; Zachary J Schlader; Caroline J Smith; Denise L Smith; June T Spector; Jennifer K Vanos; W Jon Williams; Nicole T Vargas; Susan W Yeargin Journal: Geohealth Date: 2021-08-01