Comparisons Between Normobaric Normoxic and Hypoxic Recovery on Post-exercise Hemodynamics After Sprint Interval Cycling in Hypoxia

Masahiro Horiuchi; Ayano Nishida; Shohei Dobashi; Katsuhiro Koyama

doi:10.3389/fphys.2022.843574

Comparisons Between Normobaric Normoxic and Hypoxic Recovery on Post-exercise Hemodynamics After Sprint Interval Cycling in Hypoxia

Front Physiol. 2022 Mar 24:13:843574. doi: 10.3389/fphys.2022.843574. eCollection 2022.

Authors

Masahiro Horiuchi¹, Ayano Nishida², Shohei Dobashi^{2

3}, Katsuhiro Koyama^{4

5}

Affiliations

¹ Division of Human Environmental Science, Mount Fuji Research Institute, Fuji-yoshida, Japan.
² Graduate School of Education, University of Yamanashi, Kofu, Japan.
³ Graduate School of Health and Sports Science, Juntendo University, Inzai, Japan.
⁴ Gradulate School Department of Interdisciplinary Research, University of Yamanashi, Kofu, Japan.
⁵ Faculty of Sport Science, Yamanashi Gakuin University, Kofu, Japan.

Abstract

The aim of this study was to investigate the effects of either normoxic or hypoxic recovery condition on post-exercise hemodynamics after sprint interval leg cycling exercise rather than hemodynamics during exercise. The participants performed five sets of leg cycling with a maximal effort (30 s exercise for each set) with a 4-min recovery of unloaded cycling between the sets in hypoxia [fraction of inspired oxygen (FiO₂) = 0.145]. The load during pedaling corresponded to 7.5% of the individual's body weight at the first set, and it gradually reduced from 6.5 to 5.5%, 4.5, and 3.5% for the second to fifth sets. After exercise, the participants rested in a sitting position for 30 min under normoxia (room-air) or hypoxia. Mean arterial pressure decreased over time during recovery (p < 0.001) with no condition and interaction effects (p > 0.05). Compared to pre-exercise values, at 30 min after exercise, mean arterial pressure decreased by 5.6 ± 4.8 mmHg (mean ± standard deviation) during hypoxic recovery, and by 5.3 ± 4.6 mmHg during normoxic recovery. Peripheral arterial oxygen saturation (SpO₂) at all time points (5, 10, 20, and 30 min) during hypoxic recovery was lower than during normoxic recovery (all p < 0.05). The area under the hyperemic curve of tissue oxygen saturation (StO₂) at vastus lateralis defined as reperfusion curve above the baseline values during hypoxic recovery was lower than during normoxic recovery (p < 0.05). Collectively, post-exercise hypotension after sprint interval leg cycling exercise was not affected by either normoxic or hypoxic recovery despite marked differences in SpO₂ and StO₂ during recovery between the two conditions.

Keywords: blood lactate concentration; hypotension; hypoxic vasodilation; mean arterial pressure; near infrared spectroscopy; tissue oxygen saturation.