Keiichi Yamaguchi1, Daichi Sumi2, Nanako Hayashi1, Naoki Ota1, Koki Ienaga1, Kazushige Goto3. 1. Graduate School of Sport and Health Science, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu, Shiga, 525-8577, Japan. 2. Research Center for Urban Health and Sports, Osaka City University, Osaka, Japan. 3. Graduate School of Sport and Health Science, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu, Shiga, 525-8577, Japan. kagoto@fc.ritsumei.ac.jp.
Abstract
PURPOSE: The purpose of the present study was to determine muscle blood flow and muscle oxygenation during repeated-sprint exercise under combined hot and hypoxic conditions. METHODS: In a single-blind, cross-over research design, 11 active males performed three sets of 5 × 6-s maximal sprints with 30-s active recovery on a cycling ergometer under control (CON; 23 °C, 50% rH, 20.9% FiO2), normobaric hypoxic (HYP; 23 °C, 50% rH, 14.5% FiO2), or hot + normobaric hypoxic (HH; 35 °C, 50% rH, 14.5% FiO2) conditions. The vastus lateralis muscle blood flow after each set and muscle oxygenation during each sprint were evaluated using near-infrared spectroscopy methods. RESULTS: Despite similar repeated-sprint performance among the three conditions (peak and mean power outputs, percent decrement score), HH was associated with significantly higher muscle blood flow compared with CON after the first set (CON: 0.61 ± 0.10 mL/min/100 g; HYP: 0.81 ± 0.13 mL/min/100 g; HH: 0.99 ± 0.16 mL/min/100 g; P < 0.05). The tissue saturation index was significantly lower in HYP than in CON during the latter phase of the exercise (P < 0.05), but it did not differ between HH and CON. CONCLUSION: These findings suggest that a combination of normobaric hypoxia and heat stress partially facilitated the exercise-induced increase in local blood flow, but it did not enhance tissue desaturation.
PURPOSE: The purpose of the present study was to determine muscle blood flow and muscle oxygenation during repeated-sprint exercise under combined hot and hypoxic conditions. METHODS: In a single-blind, cross-over research design, 11 active males performed three sets of 5 × 6-s maximal sprints with 30-s active recovery on a cycling ergometer under control (CON; 23 °C, 50% rH, 20.9% FiO2), normobaric hypoxic (HYP; 23 °C, 50% rH, 14.5% FiO2), or hot + normobaric hypoxic (HH; 35 °C, 50% rH, 14.5% FiO2) conditions. The vastus lateralis muscle blood flow after each set and muscle oxygenation during each sprint were evaluated using near-infrared spectroscopy methods. RESULTS: Despite similar repeated-sprint performance among the three conditions (peak and mean power outputs, percent decrement score), HH was associated with significantly higher muscle blood flow compared with CON after the first set (CON: 0.61 ± 0.10 mL/min/100 g; HYP: 0.81 ± 0.13 mL/min/100 g; HH: 0.99 ± 0.16 mL/min/100 g; P < 0.05). The tissue saturation index was significantly lower in HYP than in CON during the latter phase of the exercise (P < 0.05), but it did not differ between HH and CON. CONCLUSION: These findings suggest that a combination of normobaric hypoxia and heat stress partially facilitated the exercise-induced increase in local blood flow, but it did not enhance tissue desaturation.
Authors: Darren P Casey; Brandon D Madery; Timothy B Curry; John H Eisenach; Brad W Wilkins; Michael J Joyner Journal: J Physiol Date: 2009-11-30 Impact factor: 5.182
Authors: Erich Hohenauer; Livia Freitag; Miriam Herten; Julia Siallagan; Elke Pollock; Wolfgang Taube; Ron Clijsen Journal: Front Physiol Date: 2022-06-16 Impact factor: 4.755