TY - JOUR
T1 - Acute performance and physiological responses to repeated-sprint exercise in a combined hot and hypoxic environment
AU - Yamaguchi, Keiichi
AU - Kasai, Nobukazu
AU - Hayashi, Nanako
AU - Yatsutani, Haruka
AU - Girard, Olivier
AU - Goto, Kazushige
PY - 2020/6/1
Y1 - 2020/6/1
N2 - We investigated performance, energy metabolism, acid–base balance, and endocrine responses to repeated-sprint exercise in hot and/or hypoxic environment. In a single-blind, cross-over study, 10 male highly trained athletes completed a repeated cycle sprint exercise (3 sets of 3 × 10-s maximal sprints with 40-s passive recovery) under four conditions (control [CON; 20℃, 50% rH, FiO2: 20.9%; sea level], hypoxia [HYP; 20℃, 50% rH, FiO2: 14.5%; a simulated altitude of 3,000 m], hot [HOT; 35℃, 50% rH, FiO2: 20.9%; sea level], and hot + hypoxia [HH; 35℃, 50% rH, FiO2: 14.5%; a simulated altitude of 3,000 m]). Changes in power output, muscle and skin temperatures, and respiratory oxygen uptake were measured. Peak (CON: 912 ± 26 W, 95% confidence interval [CI]: 862–962 W, HYP: 915 ± 28 W [CI: 860–970 W], HOT: 937 ± 26 W [CI: 887–987 W], HH: 937 ± 26 W [CI: 886–987 W]) and mean (CON: 808 ± 22 W [CI: 765–851 W], HYP: 810 ± 23 W [CI: 765–855 W], HOT: 825 ± 22 W [CI: 781–868 W], HH: 824 ± 25 W [CI: 776–873 W]) power outputs were significantly greater when exercising in heat conditions (HOT and HH) during the first sprint (p <.05). Heat exposure (HOT and HH) elevated muscle and skin temperatures compared to other conditions (p <.05). Oxygen uptake and arterial oxygen saturation were significantly lower in hypoxic conditions (HYP and HH) versus the other conditions (p <.05). In summary, additional heat stress when sprinting repeatedly in hypoxia improved performance (early during exercise), while maintaining low arterial oxygen saturation.
AB - We investigated performance, energy metabolism, acid–base balance, and endocrine responses to repeated-sprint exercise in hot and/or hypoxic environment. In a single-blind, cross-over study, 10 male highly trained athletes completed a repeated cycle sprint exercise (3 sets of 3 × 10-s maximal sprints with 40-s passive recovery) under four conditions (control [CON; 20℃, 50% rH, FiO2: 20.9%; sea level], hypoxia [HYP; 20℃, 50% rH, FiO2: 14.5%; a simulated altitude of 3,000 m], hot [HOT; 35℃, 50% rH, FiO2: 20.9%; sea level], and hot + hypoxia [HH; 35℃, 50% rH, FiO2: 14.5%; a simulated altitude of 3,000 m]). Changes in power output, muscle and skin temperatures, and respiratory oxygen uptake were measured. Peak (CON: 912 ± 26 W, 95% confidence interval [CI]: 862–962 W, HYP: 915 ± 28 W [CI: 860–970 W], HOT: 937 ± 26 W [CI: 887–987 W], HH: 937 ± 26 W [CI: 886–987 W]) and mean (CON: 808 ± 22 W [CI: 765–851 W], HYP: 810 ± 23 W [CI: 765–855 W], HOT: 825 ± 22 W [CI: 781–868 W], HH: 824 ± 25 W [CI: 776–873 W]) power outputs were significantly greater when exercising in heat conditions (HOT and HH) during the first sprint (p <.05). Heat exposure (HOT and HH) elevated muscle and skin temperatures compared to other conditions (p <.05). Oxygen uptake and arterial oxygen saturation were significantly lower in hypoxic conditions (HYP and HH) versus the other conditions (p <.05). In summary, additional heat stress when sprinting repeatedly in hypoxia improved performance (early during exercise), while maintaining low arterial oxygen saturation.
KW - combination of stressors
KW - heat stress
KW - hypoxia
KW - repeated-sprints
UR - http://www.scopus.com/inward/record.url?scp=85087030550&partnerID=8YFLogxK
U2 - 10.14814/phy2.14466
DO - 10.14814/phy2.14466
M3 - Article
C2 - 32592261
AN - SCOPUS:85087030550
SN - 2051-817X
VL - 8
JO - Physiological Reports
JF - Physiological Reports
IS - 12
M1 - e14466
ER -