AUTHOR=Almeida Tiago André Freire , Pessôa Filho Dalton Müller , Espada Mário Cunha , Reis Joana Filipa , Sancassani Andrei , Massini Danilo Alexandre , Santos Fernando Jorge , Alves Francisco Besone 

TITLE=Physiological Responses During High-Intensity Interval Training in Young Swimmers

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.662029

DOI=10.3389/fphys.2021.662029

ISSN=1664-042X

ABSTRACT=<p>This study analyzed whether 100- and 200-m interval training (IT) in swimming differed regarding temporal, perceptual, and physiological responses. The IT was performed at maximal aerobic velocity (MAV) until exhaustion and time spent near to maximalVO<sub>2</sub> peak oxygen uptake (⩒O<sub>2</sub>peak), total time limit (t<sub>Lim</sub>), peak blood lactate [La<sup>−</sup>] peak, ⩒O<sub>2</sub> kinetics (⩒O<sub>2</sub>K), and rate of perceived exertion (RPE) were compared between protocols. Twelve swimmers (seven males 16.1 ± 1.1 and five females 14.2 ± 1 years) completed a discontinuous incremental step test for the second ventilatory threshold (VT<sub>2</sub>), ⩒O<sub>2</sub>peak, and MAV assessment. The swimmers subsequently completed two IT protocols at MAV with 100- and 200-m bouts to determine the maximal ⩒O<sub>2</sub> (peak-⩒O<sub>2</sub>) and time spent ≥VT<sub>2</sub>, 90, and 95% of ⩒O<sub>2</sub>peak for the entire protocols (IT<sub>100</sub> and IT<sub>200</sub>) and during the first 800-m of each protocol (IT<sub>8x100</sub> and IT<sub>4x200</sub>). A portable apparatus (K4b<sup>2</sup>) sampled gas exchange through a snorkel and an underwater led signal controlled the velocity. RPE was also recorded. The Peak-⩒O<sub>2</sub> attained during IT<sub>8x100</sub> and IT<sub>4x200</sub> (57.3 ± 4.9 vs. 57.2 ± 4.6 ml·kg<sup>−1</sup>·min<sup>−1</sup>) were not different between protocols (<italic>p</italic> = 0.98) nor to ⩒O<sub>2</sub>peak (59.2 ± 4.2 ml·kg<sup>−1</sup>·min<sup>−1</sup>, <italic>p</italic> = 0.37). The time constant of ⩒O<sub>2</sub>K (24.9 ± 8.4 vs. 25.1 ± 6.3-s, <italic>p</italic> = 0.67) and [La<sup>−</sup>] peak (7.9 ± 3.4 and 8.7 ± 1.5 mmol·L<sup>−1</sup>, <italic>p</italic> = 0.15) also did not differ between IT<sub>100</sub> and IT<sub>200</sub>. The time spent ≥VT<sub>2</sub>, 90, and 95%⩒O<sub>2</sub>peak were also not different between IT<sub>8x100</sub> and IT<sub>4x200</sub> (<italic>p</italic> = 0.93, 0.63, and 1.00, respectively). The RPE for IT<sub>8x100</sub> was lower than that for IT<sub>4x200</sub> (7.62 ± 2 vs. 9.5 ± 0.7, <italic>p</italic> = 0.01). Both protocols are considered suitable for aerobic power enhancement, since ⩒O<sub>2</sub>peak was attained with similar ⩒O<sub>2</sub>K and sustained with no differences in t<sub>Lim</sub>. However, the fact that only the RPE differed between the IT protocols suggested that coaches should consider that nx100-m/15-s is perceived as less difficult to perform compared with nx200-m/30-s for the first 800-m when managing the best strategy to be implemented for aerobic power training.</p>