Ventilatory responses during experimental cycle-run transition in triathletes

Purpose and Methods: To determine the effects of cycling on a subsequent tr iathlon run, nine male triathletes underwent four successive laboratory tri als: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 5 km of running (C-R), and 4) 30 min of running followed by 5 km of running (R-R). Before and 10 min after the third and fo urth trials, the triathletes underwent pulmonary function testing including spirometry and diffusing capacity testing for carbon monoxide (DLCO). Duri ng the C-R and R-R trials, arterialized blood samples were obtained to meas ure arterial oxygen pressure (PaO2). During all trials, ventilatory data we re collected every minute using an automated breath-by-breath system. Resul ts: The results showed that 1) the oxygen uptake ((V) over dotO(2)) observe d during subsequent running was similar for the C-R and R-R trials; 2) the ventilatory response ((V) over dot(E)) during the first 8 min of subsequent running was significantly greater in the C-R than in R-R trial (P < 0.05); 3) only the C-R trial induced a significant increase (P < 0.05) in residua l volume (RV), functional residual capacity (FRC), and the ratio of residua l volume to total lung capacity (RV/TLC); and 4) although a significant dec rease (P < 0.05) in DLCO was noted after C-R, no difference between the two exercise trials was found fur the maximal drop in PaO2. Conclusions: We co ncluded that 1) the C-R trial induced specific alterations in pulmonary fun ction that may be associated with respiratory muscle fatigue and/or exercis e-induced hypoxemia, and 2) the greater (V) over dot(E) observed during the first minute of running after cycling was due to the specificity of cyclin g. This reinforces the necessity for triathletes to practice multi-trial tr aining to stimulate the physiological responses experienced during the swim -cycle and the cycle-run transitions.