Stickford, J. L., Duke, J. W., Laymon, A. S., Stager, J. M., Chapman, R. F., Stray-Gundersen, J., & Devine, B. J. (2011). Does expiratory flow limitation mitigate performance gains in elite distance runners after chronic altitude training? Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 789.

This study retrospectively examined the hypothesis that expiratory flow limitation attenuates ventilatory acclimatization and endurance performance following altitude training in elite athletes. Elite male distance runners (N = 4 flow limited; N = 7 non-flow limited) were retrospectively categorized based on the presence of expiratory flow limitation in flow volume loops collected during the final minute of an incremental exercise bout to exhaustion at sea-level. Ss completed a 28-day altitude training intervention at 2,500 m, following a "Live High - Train Low" (HiLo) training model. During the initial exhaustive exercise bout, and also upon return from altitude, maximal oxygen uptake (VO2max) and ventilation (Vemax) were measured. Isocapnic hypoxic ventilatory response and endurance performance at sea-level (3 km time-trial) were also measured before and after HiLo training.

Isocapnic hypoxic ventilatory responses significantly increased by a similar amount in both groups, demonstrating an increase in ventilatory chemo-responsiveness. Upon return from altitude, flow-limited runners did not significantly increase VEmax compared to pre-altitude, whereas both variables significantly increased in the non-flow limited runners. Mean 3-km time did not change from pre-to post-altitude in flow-limited runners, but was slightly faster in non-flow limited runners.

Implication. Expiratory flow limitation may impair the possible beneficial effects of HiLo training, resulting in no improvements in VO2max or performance in flow-limited athletes.

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