Enhanced ventilatory and exercise performance in athletes with slight expiratory resistive loading

We determined the cardiorespiratory and performance effects of slight (1.5-3.0 cmH2O) expiratory resistive loading (ERL). Twenty-eight highly fit [peak O2 uptake (VO2 peak) = 63.6 +/- 1.3 ml . kg-1 . min-1] athletes (age = 33.5 +/- 1.3 yr) performed paired VO2 peak cycle ergometer tests (control vs. ERL). End-expiratory lung volume was separately determined in a subset of subjects (n = 12) at steady-state 75% maximum power output (POmax) and was found to increase (0.67 +/- 0.29 liter) with ERL. In the VO2 peak tests, peak expiratory pressure at the mouth, mean inspiratory flow, minute ventilation, and O2 pulse were greater with ERL at every intensity level (i.e., 75, 80, 85, and 90% POmax). Increased minute ventilation was largely due to a trend toward increased tidal volume (P < 0.05 at 80% POmax). O2 uptake was greater at 90% POmax with ERL. Increased O2 pulse with ERL at comparative workloads suggests that stroke volume was augmented with ERL. Also, with ERL, athletes attained higher VO2 peak (63.0 +/- 1.4 vs. 60.1 +/- 1.3 ml . kg-1 . min-1) and greater POmax (352.0 +/- 9.9 vs. 345.7 +/- 9.5 W). We conclude that elevated end-expiratory lung volume in response to slight ERL during strenuous exercise served to attenuate both airflow and blood flow limitations, which enhanced exercise capacity.