Catecholamine, blood lactate and ventilatory responses to multi-cycle-run blocks

Purpose and Methods: This study was designed to determine whether the physi ological responses elicited during the run part of repeated bouts of cycle- run exercise are similar to those required during the run segment of a cycl e-run succession Thirteen male triathletes underwent four successive labora tory trials: 1) an incremental treadmill test, 2) an incremental cycle test , 3) 30 min of cycling followed by 20 min of running (C-R), and 4) five rep eated bouts of 6 min of cycling and 4 min of running (X-CR). During the C-R and X-CR trials, venous blood samples were obtained to measure lactate, ep inephrine and norepinephrine concentrations. During all trials. ventilatory data were collected every min using an automated breath-by-breath system. Results: The results showed that 1) the cardiorespiratory responses observe d during running were similar in the X-CR and C-R trials, 2) the lactate co ncentration was similar in both trials, 3) the epinephrine concentration wa s greater (277.9 +/- 11.9 vs 169.8 +/- 86.7 pg.mL(-1), P < 0.025) in X-CR t han in C-R and 4) the norepinephrine concentration was similar in both tria ls, except at the first cycle-run succession (T1) of X-CR. Conclusion: We c oncluded that 1) multi-block training is a good method to stimulate the spe cific adaptations required for the cycle-run succession. and particularly f or the cycle-run transition, and 2) multi-block training seems to induce a greater catecholaminergic response, which may be due to a combination of an inherent effect of this type of training and the triathletes' relative lac k of experience with it. In any case, the efficacy of the multi-block model needs to be more thoroughly evaluated over the course of a longer-term tra ining program.