Open AccessAcute performance and physiological responses to repeated‐sprint exercise in a combined hot and hypoxic environment
Author(s) -
Yamaguchi Keiichi,
Kasai Nobukazu,
Hayashi Nanako,
Yatsutani Haruka,
Girard Olivier,
Goto Kazushige
Publication year - 2020
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.14466
Subject(s) - sprint , hypoxia (environmental) , medicine , respiratory exchange ratio , effects of high altitude on humans , vo2 max , zoology , oxygen , endocrinology , chemistry , heart rate , cardiology , physical therapy , blood pressure , biology , anatomy , organic chemistry
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, FiO 2 : 20.9%; sea level], hypoxia [HYP; 20℃, 50% rH, FiO 2 : 14.5%; a simulated altitude of 3,000 m], hot [HOT; 35℃, 50% rH, FiO 2 : 20.9%; sea level], and hot + hypoxia [HH; 35℃, 50% rH, FiO 2 : 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.