Noordhof, D., A., Schoots, T., Hoekert, D., de Koning, J. J., & Foster, C. (2011). Gross efficiency at sea level and moderate altitude. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 792.

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This study compared gross efficiency at sea-level and moderate altitude. Trained male cyclists (N = 16) completed a maximal incremental exercise test at sea-level and at simulated altitude (1,500 m, hypobaric hypoxia), as well as a gross efficiency test at sea-level and altitude. Gross efficiency was determined between minutes three to six during submaximal exercise at 55% PVO2max. Pedaling frequency was maintained at 80 rpm. Oxygen uptake, respiratory exchange ratio, and ventilation were continuously measured and rating of perceived exertion and oxygen saturation were monitored at fixed time intervals.

Absolute oxygen uptake was significantly higher at sea-level than at altitude. Respiratory exchange ratio was significantly lower at sea-level. Gross efficiency at sea-level was significantly higher than at simulated altitude. Ventilation and ratings of perceived exertion were not significantly different between conditions. Oxygen saturation was significantly lower at moderate altitude.

Implication. Moderate altitude resulted in a significantly lower gross efficiency during cycling when compared to sea-level. Although oxygen saturation was significantly lower at altitude, there was no significant difference in ventilation.

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