Effect of stage duration on maximal heart rate and post-exercise blood lactate concentration during incremental treadmill tests

摘要

Objectives: This study compared the responses during maximal incremental treadmill tests of 1-min, 2-min, and 3-min stage durations mainly in terms of maximal heart rate (HRmax) and peak blood lactate concentration (LApeak). Design: Repeated-measures. Methods: Thirty-four male, recreational, endurance-trained runners (40±13 years) performed three tests on a motorized treadmill. The tests started at 8kmh-1 with increments of 1kmh-1 every 1min for the short-stage protocol, every 2min for the intermediate-stage protocol, and every 3min for the long-stage protocol. LApeak was defined for each subject as the highest value among the lactate concentrations determined at the end of each test and at the third, fifth and seventh minutes after test, during passive recovery. Results: Analysis of variance revealed a significant effect of the stage duration on the HRmax (p=0.003) and LApeak (p=0.001). The HRmax was higher in the intermediate-stage compared to the short-stage protocol (184.8±12.7 vs. 181.8±12.1beatsmin-1, p0.001), but no significant differences were found between the long-stage (183.1±12.1beatsmin-1) and the intermediate-stage or short-stage protocols (p0.05). The LApeak was lower in the long-stage compared to the short-stage and intermediate-stage protocols (7.9±2.2 vs. 9.4±2.2 and 9.2±1.9mmolL-1, respectively, p0.05). Further, blood lactate reached peak concentration at the fifth minute after test for all the protocols. Conclusions: Thus, HRmax and LApeak depend on the stage duration of the incremental test, but the moment at which blood lactate reaches peak concentration is independent of the duration. Further, we suggest 2-min stage duration protocols to determine HRmax.