Time-course for onset and decay of physiological adaptations in endurance trained athletes undertaking prolonged heat acclimation training
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Time-course for onset and decay of physiological adaptations in endurance trained athletes undertaking prolonged heat acclimation training. / Cubel, Claes; Fischer, Mads; Stampe, Daniel; Klaris, Magnus B.; Bruun, Tim R.; Lundby, Carsten; Nordsborg, Nikolai B.; Nybo, Lars.
In: Temperature, 2024.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Time-course for onset and decay of physiological adaptations in endurance trained athletes undertaking prolonged heat acclimation training
AU - Cubel, Claes
AU - Fischer, Mads
AU - Stampe, Daniel
AU - Klaris, Magnus B.
AU - Bruun, Tim R.
AU - Lundby, Carsten
AU - Nordsborg, Nikolai B.
AU - Nybo, Lars
N1 - Publisher Copyright: © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
PY - 2024
Y1 - 2024
N2 - Short-term heat acclimation (HA) appears adequate for maximizing sudomotor adaptations and enhancing thermal resilience in trained athletes. However, for enhanced erythropoiesis and transfer effects to exercise capacity in cooler environments, prolonged HA appears necessary. To establish the time-course for physiological adaptations and performance effects, 20 male elite cyclists were divided into an intervention group (HEAT; n = 10) completing 5 weeks of HA (six one-hour HA-training sessions per week) and control (n = 10) tested pre and post in hot (40°C) and cool conditions (20°C). HEAT completed tests at 40°C every week during HA with measures of sweat rate and [Na+] and a decay test 2 weeks after termination of HA. HEAT improved time for exhaustion by 15 min (p < 0.001) in the 40°C test, increased sweat rate by 0.44 L/hour (p < 0.001), and lowered sweat sodium concentration [Na+] by 14.1 mmol/L (p = 0.006) from pre- to post-HA, with performance returning to pre-HA levels in the 2-week decay test. Total hemoglobin mass (tHbmass) was increased by 30 grams (+3%, p = 0.048) after 3 weeks and 40 grams (+4%, p = 0.038) after 5 weeks in HEAT but returned to pre-HA levels at the 2-week decay test. HEAT improved incremental peak power output (+12 W, p = 0.001) without significant changes in maximal oxygen uptake (p = 0.094). In conclusion, improvements in heat exercise tolerance and sudomotor adaptations materialized during the first ~3 weeks and the entire 5 weeks of HA augmented both cool exercise capacity and tHbmass. However, the 2-week post-HA evaluation demonstrated a rapid decay of physiological adaptations and exercise capacity in the heat.
AB - Short-term heat acclimation (HA) appears adequate for maximizing sudomotor adaptations and enhancing thermal resilience in trained athletes. However, for enhanced erythropoiesis and transfer effects to exercise capacity in cooler environments, prolonged HA appears necessary. To establish the time-course for physiological adaptations and performance effects, 20 male elite cyclists were divided into an intervention group (HEAT; n = 10) completing 5 weeks of HA (six one-hour HA-training sessions per week) and control (n = 10) tested pre and post in hot (40°C) and cool conditions (20°C). HEAT completed tests at 40°C every week during HA with measures of sweat rate and [Na+] and a decay test 2 weeks after termination of HA. HEAT improved time for exhaustion by 15 min (p < 0.001) in the 40°C test, increased sweat rate by 0.44 L/hour (p < 0.001), and lowered sweat sodium concentration [Na+] by 14.1 mmol/L (p = 0.006) from pre- to post-HA, with performance returning to pre-HA levels in the 2-week decay test. Total hemoglobin mass (tHbmass) was increased by 30 grams (+3%, p = 0.048) after 3 weeks and 40 grams (+4%, p = 0.038) after 5 weeks in HEAT but returned to pre-HA levels at the 2-week decay test. HEAT improved incremental peak power output (+12 W, p = 0.001) without significant changes in maximal oxygen uptake (p = 0.094). In conclusion, improvements in heat exercise tolerance and sudomotor adaptations materialized during the first ~3 weeks and the entire 5 weeks of HA augmented both cool exercise capacity and tHbmass. However, the 2-week post-HA evaluation demonstrated a rapid decay of physiological adaptations and exercise capacity in the heat.
KW - cycling
KW - endurance-trained cyclists
KW - Heat acclimation
KW - hemoglobin mass
KW - performance
KW - sudomotor adaptations
U2 - 10.1080/23328940.2024.2383505
DO - 10.1080/23328940.2024.2383505
M3 - Journal article
AN - SCOPUS:85200122693
JO - Temperature
JF - Temperature
SN - 2332-8940
ER -
ID: 402750032