Breathing a low-density gas reduces respiratory muscle force development and marginally improves exercise performance in master athletes

Introduction We tested the hypothesis that breathing heliox, to attenuate the mechanical constraints accompanying the decline in pulmonary function with aging, improves exercise performance. Methods Fourteen endurance-trained older men (67.9 ± 5.9 year, V̇ O 2max : 50.8 ± 5.8 ml/kg/min; 151