Sessional work-rate does not affect the magnitude to which simulated hypoxia can augment acute physiological responses d
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ORIGINAL ARTICLE
Sessional work‑rate does not affect the magnitude to which simulated hypoxia can augment acute physiological responses during resistance exercise Thomas P. Walden1 · Olivier Girard2 · Andrew M. Jonson1 · Alasdair R. Dempsey1 · Kieran J. Marston1 · Brendan R. Scott1 Received: 30 March 2020 / Accepted: 16 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose To investigate whether performing resistance exercise in hypoxia augments physiological and perceptual responses, and if altering work-rate by performing repetitions to failure compared to sub-maximally increases the magnitude of these responses. Methods Twenty male university students (minimum of 2 year resistance training experience) completed four sessions, two in hypoxia (fraction of inspired oxygen [FiO2] = 0.13), and two in normoxia (FiO2 = 0.21). For each condition, session one comprised three sets to failure of shoulder press and bench press (high work-rate session), while session two involved the same volume load, distributed over six sets (low work-rate session). Muscle oxygenation (triceps brachii), surface electromyographic activity (anterior deltoid, pectoralis major, and triceps brachii), heart rate (HR), and arterial blood oxygen saturation were recorded. Blood lactate concentration ( [Bla−]) was recorded pre-exercise and 2 min after each exercise. Muscle thickness was measured pre- and post-exercise via ultrasound. Results Muscle oxygenation values during sets and inter-set rest periods were lower in hypoxia vs normoxia (p = 0.001). Hypoxia caused greater [Bla−] during the shoulder press of failure sessions (p = 0.003) and both shoulder press (p = 0.048) and bench press (p = 0.005) of non-failure sessions. Hypoxia increased HR during non-failure sessions (p 2000 m in the previous six months, had pre-existing conditions which could have been exacerbated by taking part, or did not meet the inclusion criteria. Participants were encouraged to refrain from strenuous activity throughout the study, and to replicate their dietary and fluid intake for 24 h before all testing sessions to control the impact of both energy availability and hydration status. As experimental sessions were highly strenuous, a wellness question was completed before each session monitoring fatigue, sleep, muscle soreness, stress levels, and mood (McLean et al. 2010), with no significant differences identified between sessions for all measures (p ≥ 0.272). Prior to participating, individuals were provided with information detailing the purpose and requirements of the research, were screened for medical contraindications, and provided signed informed consent. There were no adverse effects caused by the prescribed exercise or the environmental conditions. This study was approved by the Murdoch University Human Research Ethics Committee (2018/052).
Procedures Familiarisation session All sessions were conducted within the exercise science laboratories at Murdoch University (750–760 mmHg barometric pressure and FiO2 = 0.21
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