• Thomas E Dolmage, Rachael A Evans, Dina Brooks, and Roger S Goldstein.
• Department of Respiratory Medicine (Mr Dolmage and Drs Evans, Brooks, and Goldstein) and Respiratory Diagnostic and Evaluation Services (Mr Dolmage and Dr Goldstein), West Park Healthcare Centre, Toronto, Canada; Department of Infection, Immunity and Inflammation, Leicester University, Leicester, UK (Dr Evans); and Department of Physical Therapy (Drs Brooks and Goldstein) and Department of Medicine (Drs Evans and Goldstein), University of Toronto, Toronto, Canada.
• J Cardiopulm Rehabil Prev. 2014 Jan 1; 34 (1): 69-74.

PurposePartitioning exercise by 1-legged cycling is more effective than conventional training in patients with chronic obstructive pulmonary disease. Similarly, inhaling helium-hyperoxia can extend conventional exercise tolerance. This study aimed to determine whether breathing helium-hyperoxia could increase the tolerance of a high-intensity exercise session achieved by 1-legged cycling.MethodsParticipants completed 2 high-intensity, constant power, 1-legged cycle tests to intolerance (tlimit). In a randomized order, they inspired 40% oxygen with the balance helium via mask and 1-way valve, 1-legged helium-hyperoxia (1L-HH), or room air with supplemental oxygen via a nasal cannula, 1-legged nitrogen-hyperoxia (1L-NH). We assessed quadriceps fatigue from the change in maximal voluntary contraction (FMVC) and transcutaneously stimulated twitch force (Ftwitch).ResultsFifteen participants (forced expiratory volume in 1 second [SD] = 36 [18]% predicted; forced expiratory volume in 1 second/forced vital capacity = 34 [14]%; peak oxygen uptake = 12.8 [2.9] mL · kg · min) completed the study. Self-reported "leg fatigue" was a reason for stopping 25 of 30 tests. There was no significant difference in tlimit (0.2 [-1.4 to 1.8] min) between 1L-HH (12.2 [5.2] min) and 1L-NH (12.0 [4.1] min), or in FMVC measured shortly after HH and NH tests (P= .09). The Ftwitch was less after exercise (P< .05) in both conditions, without a difference between conditions (P= .46).ConclusionsInspiring a helium-hyperoxia mixture does not increase the endurance of what would be a typical training session, breathing supplemental oxygen, of high-intensity 1-legged constant power exercise. Leg muscle fatigue was similar after 1-legged exercise with and without breathing the helium mixture.

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