AUTHOR=Wiewelhove Thimo , Schneider Christoph , Schmidt Alina , Döweling Alexander , Meyer Tim , Kellmann Michael , Pfeiffer Mark , Ferrauti Alexander 

TITLE=Active Recovery After High-Intensity Interval-Training Does Not Attenuate Training Adaptation

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.00415

DOI=10.3389/fphys.2018.00415

ISSN=1664-042X

ABSTRACT=<p><bold>Objective:</bold> High-intensity interval training (HIIT) can be extremely demanding and can consequently produce high blood lactate levels. Previous studies have shown that lactate is a potent metabolic stimulus, which is important for adaptation. Active recovery (ACT) after intensive exercise, however, enhances blood lactate removal in comparison with passive recovery (PAS) and, consequently, may attenuate endurance performance improvements. Therefore, the aim of this study was to examine the influence of regular ACT on training adaptations during a HIIT mesocycle.</p><p><bold>Methods:</bold> Twenty-six well-trained male intermittent sport athletes (age: 23.5 ± 2.5 years; <inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max: 55.36 ± 3.69 ml min kg<sup>-1</sup>) participated in a randomized controlled trial consisting of 4 weeks of a running-based HIIT mesocycle with a total of 12 HIIT sessions. After each training session, participants completed 15 min of either moderate jogging (ACT) or PAS. Subjects were matched to the ACT or PAS groups according to age and performance. Before the HIIT program and 1 week after the last training session, the athletes performed a progressive incremental exercise test on a motor-driven treadmill to determine <inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max, maximum running velocity (vmax), the running velocity at which <inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max occurs (v<inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max), and anaerobic lactate threshold (AT). Furthermore, repeated sprint ability (RSA) were determined.</p><p><bold>Results:</bold> In the whole group the HIIT mesocycle induced significant or small to moderate changes in vmax (<italic>p</italic> &lt; 0.001, effect size [ES] = 0.65,), v<inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max (<italic>p</italic> &lt; 0.001, ES = 0.62), and AT (<italic>p</italic> &lt; 0.001, ES = 0.56) compared with the values before the intervention. <inline-graphic xlink:href="fphys-09-00415-i001.jpg" xmlns:xlink="http://www.w3.org/1999/xlink" />O<sub>2</sub>max and RSA remained unchanged throughout the study. In addition, no significant differences in the changes were noted in any of the parameters between ACT and PAS except for AT (<italic>p</italic> &lt; 0.05, ES = 0.57).</p><p><bold>Conclusion:</bold> Regular use of individualized ACT did not attenuate training adaptations during a HIIT mesocycle compared to PAS. Interestingly, we found that the ACT group obtained a significantly higher AT following the training program compared to the PAS group. This could be because ACT allows a continuation of the training at a low intensity and may activate specific adaptive mechanisms that are not triggered during PAS.</p>