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RESEARCH PRODUCT

Effects of high-intensity training on physiological and hormonal adaptions in well-trained cyclists

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Purpose: This study aimed to compare the effects of three different high-intensity training (HIT) models, balanced for total load but differing in training plan progression, on endurance adaptations. Methods: Sixty-three cyclists (peak oxygen uptake (V˙ O2peak) 61.3 T 5.8 mLIkgj1 Iminj1 ) were randomized to three training groups and instructed to follow a 12-wk training program consisting of 24 interval sessions, a high volume of low-intensity training, and laboratory testing. The increasing HIT group (n = 23) performed interval training as 4 16 min in weeks 1–4, 4 8 min in weeks 5–8, and 4 4 min in weeks 9–12. The decreasing HIT group (n = 20) performed interval sessions in the opposite mesocycle order as the increasing HIT group, and the mixed HIT group (n = 20) performed the interval prescriptions in a mixed distribution in all mesocycles. Interval sessions were prescribed as maximal session efforts and executed at mean values 4.7, 9.2, and 12.7 mmolILj1 blood lactate in 4 16-, 4 8-, and 4 4-min sessions, respectively (P G 0.001). Pre- and postintervention, cyclists were tested for mean power during a 40-min all-out trial, peak power output during incremental testing to exhaustion, V˙ O2peak, and power at 4 mmolILj1 lactate. Results: All groups improved 5%–10% in mean power during a 40-min all-out trial, peak power output, and V˙ O2peak postintervention (P G 0.05), but no adaptation differences emerged among the three training groups (P 9 0.05). Further, an individual response analysis indicated similar likelihood of large, moderate, or nonresponses, respectively, in response to each training group (P 9 0.05). Conclusions: This study suggests that organizing different interval sessions in a specific periodized mesocycle order or in a mixed distribution during a 12-wk training period has little or no effect on training adaptation when the overall training load is the same. Copyright 2016 the Author(s). Published by Wolters Kluwer Health on behalf of the American College of Sports Medicine. This is an open-access article distributed under the terms of the Creative Commons AttributionNon Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.