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Supramaximal Intensity Hypoxic Exercise and Vascular Function Assessment in Mice
Published on: March 15, 2019
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Load carriage physiology in normoxia and hypoxia
Daniel A Baur1, Katherine G Baur2, Beverley K Buchanan2
1Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA. baurda@vmi.edu.
European Journal of Applied Physiology
|September 23, 2023
Summary
Load carriage significantly reduces cardiorespiratory efficiency and increases physiological strain, especially in hypoxic conditions. This impacts oxygen delivery and utilization, potentially increasing risks associated with altitude exposure.
Area of Science:
- Exercise Physiology
- Environmental Physiology
- Human Performance
Background:
- Load carriage is a common activity in military and recreational settings.
- Understanding the physiological strain of load carriage, particularly under hypoxic conditions, is crucial for optimizing performance and safety.
Purpose of the Study:
- To investigate the effects of load carriage in both normoxia and normobaric hypoxia on key physiological responses.
- To assess changes in ventilatory responses, hemodynamics, tissue oxygenation, and metabolism during loaded exercise.
Main Methods:
- Healthy males (n=12) underwent graded exercise tests under unloaded normoxic, loaded normoxic, and loaded hypoxic conditions.
- Experimental trials involved walking with a ~30 kg load at matched absolute oxygen consumption (VO2) and speed.
Main Results:
- Load carriage reduced maximal oxygen consumption (VO2max) by 7% in normoxia and 32% in hypoxia.
- At matched VO2, stroke volume and tidal volume decreased with load carriage.
- Hypoxia exacerbated the effects of load carriage, increasing reliance on carbohydrate metabolism and reducing muscle oxygenation.
Conclusions:
- Load carriage diminishes cardiorespiratory efficiency and elevates physiological strain, with significantly greater effects in hypoxic environments.
- Altered cerebral blood flow during loaded, hypoxic exercise may elevate the risk of altitude-related illnesses, warranting further investigation.
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