17th Annual ECSS-Congress, Bruges 2012

Abstract details

Abstract-ID: 543
Session: [PO-CPP-16] Physiology 4
Lecture room: Gallery
Date & time: 09.07.2016 / -
Title of the paper: Effects of Hyperoxia on Muscular Endurance
Authors: Kojima, Y., Fukusaki, C., Ishii, N.
Institution: The University of Tokyo
Department: Graduate School of Frontier Sciences
Country: Japan
Abstract text Introduction A number of studies have shown that hyperoxic environment can enhance the aerobic endurance, whereas its effect on the muscular endurance has not been well understood. This study investigated the endurance performance, activation level and tissue oxygenation in the working muscle during repeated weight-lifting tasks in the hyperoxic environment. Methods Ten healthy young men performed repetition of one-hand preacher curl at an intensity of 30%1RM until exhaustion in two separate sessions: one was under normoxic condition (20.9%O2) and the other under hyperoxic condition (30.0%O2). Each session was conducted on a different day in randomized order. During the exercise, electromyographic activity (EMG) and oxygenation level of the biceps brachii muscle were measured with surface electrodes and near-infrared spectroscopy (NIRS), respectively. Root mean square (RMS) of EMG was normalized to that at the maximal voluntary contraction. In NIRS, changes in oxygenated, deoxygenated, and total hemoglobin levels from those at rest, and tissue oxygenation index were analyzed. All of these values were averaged for five repetitions. Since the maximal number of repetition varied with subjects and oxygen conditions, the mean values for the first, middle and last five repetitions were compared between hyperoxic and normoxic conditions. Results The maximal number of repetition under the hyperoxic condition was significantly larger than that under the normoxic condition. For all parameters relating to muscle activation and oxygenation, two-way analysis of variance tests showed no significant effects of oxygen concentration (normoxia vs. hyperoxia), but significant time effects (the first, middle, and last five repetitions). Significant interaction effects were found in RMS of EMG, oxygenated hemoglobin level, deoxygenated hemoglobin level, and tissue oxygenation index. Multiple comparison tests showed that only RMS of EMG during the last five repetitions was significantly larger under normoxia than under hyperoxia. Discussion These results indicate that hyperoxia can improve muscular endurance by delaying the fatigue-induced elevation of muscle activation. However, the muscle oxygenation level may not be related to this effect. Intramuscular H+ during exercise is lower under hyperoxic condition than normoxic condition (Eiken and Tesch, 1984; Adams and Welch, 1980), which could cause the positive effects of hyperoxia on muscular endurance. References Adams RP, Welch HG. (1980). J Appl Physiol Respir Environ Exerc Physiol, 49(5), 863-8. Eiken O, Tesch PA. (1984). Acta Physiol Scand, 122(4), 629-33. Contact Email: d157616@h.k.u-tokyo.ac.jp
Topic: Physiology
Keyword I: hyperoxia
Keyword II: muscular endurance
Keyword III: EMG