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Breathing Helium–Hyperoxia and Tolerance of Partitioned Exercise in Patients With COPD

PURPOSE: Partitioning 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. METHODS: Participants 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). RESULTS: Fifteen 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−1·min−1) 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). CONCLUSIONS: Inspiring 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.