We studied the effects of running on ventilatory muscle strength and endurance in 11 adults enrolled in a physical fitness program. Twelve healthy volunteers were used as a control group. Maximum expiratory pressure (Paomax), maximum voluntary ventilation (MVV), peak inspiratory flow, forced expiratory volume in 1 s, forced vital capacity, and maximum sustainable ventilatory capacity for 15 min (MSVC) were measured at 0, 10, and 20 wk. At the end of the 10-wk program, the subject group demonstrated a significant increase in both MSVC and MVV. At the end of the 20-wk period, the subject group demonstrated a significant increase in expiratory Paomax (14.4%), MVV (13.6%), and MSVC (15.8%). There was no significant change at the end of the 20-wk period in any of the tests in the control group. These data indicate that running can improve ventilatory muscle strength and endurance in healthy, previously sedentary individuals.