Oxygen uptake during the last bouts of exercise incorporated into high-intensity intermittent cross-exercise exceeds the V˙ O2max of the same exercise mode
{"title":"Oxygen uptake during the last bouts of exercise incorporated into high-intensity intermittent cross-exercise exceeds the V˙ O2max of the same exercise mode","authors":"Yuzhong Xu, Xin Liu, Katsunori Tsuji, Takafumi Hamaoka, Izumi Tabata","doi":"10.1016/j.smhs.2024.01.002","DOIUrl":null,"url":null,"abstract":"<div><p>Oxygen uptake (<span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>) was measured during a non-exhaustive high-intensity intermittent cross-exercise (HIICE) protocol consisting of four alternating bouts of 20 s running (R) and three bouts of bicycle exercise (BE) at ∼160% and ∼170% maximal oxygen uptake (<span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>max), respectively, with 10 s between-bout rests (sequence R-BE-R-BE-R-BE-R). The <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub> during the last BE ([52.2 ± 5.0] mL·kg<sup>−1</sup>·min<sup>−1</sup>) was significantly higher than the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>max of the BE ([48.0 ± 5.4] mL·kg<sup>−1</sup>·min<sup>−1</sup>, <em>n</em> = 30) and similar to that of running. For clarifying the underlying mechanisms, a corresponding HIICE-protocol with BE and arm cranking ergometer exercise (AC) was used (sequence AC-AC-BE-AC-BE-AC-AC-BE). In some experiments, thigh blood flow was occluded by a cuff around the upper thigh. Without occlusion, the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub> during the AC ([39.2 ± 7.1] mL·kg<sup>−1</sup>·min<sup>−1</sup> [6<sup>th</sup> bout]) was significantly higher than the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>max of AC ([30.2 ± 4.4] mL·kg<sup>−1</sup>·min<sup>−1</sup>, <em>n</em> = 7). With occlusion, the corresponding <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub> ([29.8 ± 3.9] mL·kg<sup>−1</sup>·min<sup>−1</sup>) was reduced to that of the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>max of AC and significantly less than the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub> without occlusion. These findings suggest that during the last bouts of HIICE may exceed the of the specific exercise, probably because it is a summation of the <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub> for the ongoing exercise plus excess post-oxygen consumption (EPOC) produced by the previous exercise with a higher <span><math><mrow><mover><mi>V</mi><mo>˙</mo></mover></mrow></math></span> O<sub>2</sub>max.</p></div>","PeriodicalId":33620,"journal":{"name":"Sports Medicine and Health Science","volume":"6 1","pages":"Pages 63-69"},"PeriodicalIF":2.3000,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666337624000027/pdfft?md5=31f356063ad4715c06dbbb4eeb7cbdd7&pid=1-s2.0-S2666337624000027-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Sports Medicine and Health Science","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2666337624000027","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"SPORT SCIENCES","Score":null,"Total":0}
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Abstract
Oxygen uptake ( O2) was measured during a non-exhaustive high-intensity intermittent cross-exercise (HIICE) protocol consisting of four alternating bouts of 20 s running (R) and three bouts of bicycle exercise (BE) at ∼160% and ∼170% maximal oxygen uptake ( O2max), respectively, with 10 s between-bout rests (sequence R-BE-R-BE-R-BE-R). The O2 during the last BE ([52.2 ± 5.0] mL·kg−1·min−1) was significantly higher than the O2max of the BE ([48.0 ± 5.4] mL·kg−1·min−1, n = 30) and similar to that of running. For clarifying the underlying mechanisms, a corresponding HIICE-protocol with BE and arm cranking ergometer exercise (AC) was used (sequence AC-AC-BE-AC-BE-AC-AC-BE). In some experiments, thigh blood flow was occluded by a cuff around the upper thigh. Without occlusion, the O2 during the AC ([39.2 ± 7.1] mL·kg−1·min−1 [6th bout]) was significantly higher than the O2max of AC ([30.2 ± 4.4] mL·kg−1·min−1, n = 7). With occlusion, the corresponding O2 ([29.8 ± 3.9] mL·kg−1·min−1) was reduced to that of the O2max of AC and significantly less than the O2 without occlusion. These findings suggest that during the last bouts of HIICE may exceed the of the specific exercise, probably because it is a summation of the O2 for the ongoing exercise plus excess post-oxygen consumption (EPOC) produced by the previous exercise with a higher O2max.