Effects of stage duration in incremental running tests on physiological variables

Effects of stage duration in incremental running tests on physiological variables.Kuipers H, Rietjens G, Verstappen F, Schoenmakers H, Hofman G.Department of Movement Sciences, University Maastricht, The Netherlands. Harm.kuipers@bw.unimaas.nlTo study the effect of stage duration on some physiological variables in an incremental running test, 8 well-trained runners underwent 3 running tests, with stage durations of 1, 3 and 6 min. To study maximal lactate steady state (maxLASS) and its corresponding speed, every subject underwent a 4th test with three 15-min stages at three speeds, based on the running speed at 4 mmol/l blood lactate (V4) in the 6 min per stage protocol. The first load in the 15 min per stage test was V4 - 0.5 km/h, the second at V4, and the third V4 + 0.5 km/h. To compare the maxLASS speed with outdoor performance, the subjects also ran 5 km at this speed on an outdoor track. Mean maximal running speed (V (max)) in the incremental test was significantly lower in the 6-min (15.1 km/h) and 3-min stage protocol (17.1 km/h), compared with the 1-min stage protocol (18.3 km/h). Mean peak VO (2) and mean peak heart rate were not different between the protocols with different stage duration. The mean V4 was significantly lower in the 6 min per stage protocol compared with the 3 min per stage protocol (12.9 vs. 14.4 km/h). Mean ventilatory threshold was not different between the 1, 3 and 6 min per stage protocols. No threshold behaviour was found in respiratory rate. MaxLASS can be estimated from V4 in the 6 min per stage protocol, and verified by three 15-min intensities being V4 - 0.5 km/h, at V4, and V4 + 0.5 km/h. The mean blood lactate concentration at the maxLASS speed was not different between treadmill running and outdoor running on a track. In conclusion, for measuring peak values of physiological variables in an incremental running test, the duration per stage is of less importance, however, when measuring blood lactate concentration as a function of running speed, the duration per stage should be at least 6 mi