Pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise in young trained and untrained adults.

To investigate pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise and to study the effects of physical fitness on these responses, nine trained and nine untrained healthy male subjects aged 18-33 years performed the force-velocity (F-v) exercise test. This test consisted of 6-s sprints against increasing braking forces (F) separated by 5-min recovery periods. Oxygen uptake (VO2), carbon dioxide output (VCO2), and ventilation (VE) were continuously measured during the test and the magnitudes of their responses to the sprints were then calculated. For all subjects VO2 increased rapidly after beginning the sprints, and the peaks of the responses (F = 13.4; P < 0.001), end of recovery values (F = 6.5; P < 0.01), and VO2 magnitudes of response (F = 12.4; P < 0.001) rose significantly with the repetition of the sprints. The VO2 magnitudes of response correlated with the corresponding sprint power outputs (r = 0.55; P < 0.001) and with the sprint repetitions (r = 0.51, P < 0.001). The VCO2 (F = 7.1; P < 0.01) and VE (F = 5.0; P < 0.01) peaks of response increased with the initial load incrementation, then stabilized when the subjects attained peak power output. End of recovery VCO2 (F = 18.0; P < 0.001) and VE (F = 14.1; P < 0.001) values rose with increasing F. The F-v peak VO2, VCO2, VE, tidal volume and respiratory frequency responses attained 53%, 40%, 44%, 66%, and 82% of the peak values measured at exhaustion of maximal graded exercise, respectively. (ABSTRACT TRUNCATED AT 250 WORDS)