AUTHOR=Harrison Amelia J. , Burdon Catriona A. , Groeller Herbert , Peoples Gregory E. 

TITLE=The Acute Physiological Responses of Eccentric Cycling During the Recovery Periods of a High Intensity Concentric Cycling Interval Session

JOURNAL=Frontiers in Physiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.00336

DOI=10.3389/fphys.2020.00336

ISSN=1664-042X

ABSTRACT=<p>Eccentric and concentric exercise is associated with disparate acute and chronic responses. We uniquely interspersed workload equivalent eccentric cycling during each recovery period of a high intensity interval training (HIIT) cycling trial to determine acute cardiopulmonary, thermal and psycho-physiological responses. Twelve males [age 28 years (SD 6), peak oxygen consumption 48 mL ⋅ kg<sup>–1</sup> ⋅ min<sup>–1</sup> (SD 6)] completed two high intensity interval cycling trials [4 × 5 min, 60% peak power output (PPO)] separated by 7–10 days. The <bold>CON<sub>R</sub></bold> trial required participants to cycle concentrically during each recovery period (5 min, 30% PPO). The <bold>ECC</bold><sub>R</sub> trial modified the recovery to be eccentric cycling (5 min, 60% PPO). High intensity workload (<bold>CON<sub>R</sub></bold>: 187 ± 17; <bold>ECC</bold><sub>R</sub>: 187 ± 21 W), oxygen consumption (<bold>CON<sub>R</sub></bold>: 2.55 ± 0.17; <bold>ECC</bold><sub>R</sub>: 2.68 ± 0.20 L ⋅ min<sup>–1</sup>), heart rate (<bold>CON<sub>R</sub></bold>: 165 ± 7; <bold>ECC</bold><sub>R</sub>: 171 ± 10 beats ⋅ min<sup>–1</sup>) and RPE legs (<bold>CON<sub>R</sub></bold>: 15 ± 3; <bold>ECC</bold><sub>R</sub>: 15 ± 3) were equivalent between trials. Eccentric cycling recovery significantly increased external workload (<bold>CON<sub>R</sub></bold>: 93 ± 18; <bold>ECC</bold><sub>R</sub>: 196 ± 24 W, <italic>P</italic> &lt; 0.01) yet lowered oxygen consumption (<bold>CON<sub>R</sub></bold>: 1.51 ± 0.18; <bold>ECC</bold><sub>R</sub>: 1.20 ± 0.20 L ⋅ min<sup>–1</sup>, <italic>P</italic> &lt; 0.05) while heart rate (<bold>CON<sub>R</sub></bold>: 132 ± 13; <bold>ECC</bold><sub>R</sub>: 137 ± 12 beats ⋅ min<sup>–1</sup>) and RPE of the legs (<bold>CON<sub>R</sub></bold>: 11 ± 7; <bold>ECC</bold><sub>R</sub>: 12 ± 7) remained equivalent. There was no significant difference in the aural temperature between the trials (<bold>ECC</bold><sub>R</sub>: 37.3 ± 0.1°C; <bold>CON<sub>R</sub></bold>: 37.4 ± 0.1°C, <italic>P</italic> &gt; 0.05), yet during recovery periods mean skin temperature was significantly elevated in the <bold>ECC</bold><sub>R</sub> (<bold>ECC</bold><sub>R</sub>: 33.9 ± 0.2°C; <bold>CON<sub>R</sub></bold>: 33.3 ± 0.2°C, <italic>P</italic> &lt; 0.05). Participants preferred <bold>ECC</bold><sub>R</sub> (10/12) and rated the <bold>ECC</bold><sub>R</sub> as more achievable (82.8 ± 11.4 mm) than <bold>CON<sub>R</sub></bold> (79.4 ± 15.9 mm, <italic>P</italic> &lt; 0.01). In conclusion, eccentric cycling during the recovery period of a HIIT training session, offers a novel approach to concurrent training methodology. The unique cardiopulmonary and skeletal muscle responses facilitate the achievement of both training stimuli within a single exercise bout.</p>