Altering the rest interval during high‐intensity interval training does not affect muscle or performance adaptations. Issue 2 (9th October 2012)

• Record Type: Journal Article
• Authors: Edge, Johann; Eynon, Nir; McKenna, Michael J.; Goodman, Craig A.; Harris, Roger C.; Bishop, David J.
• Is Part Of: Experimental physiology. Volume 98:Issue 2(2013:Feb.)
• Page Start: 481
• Page End: 490
• Publication Date: 2012-10-09
• Subjects: Physiology, Experimental -- Periodicals; 571.0724
• DOI: 10.1113/expphysiol.2012.067603
• Languages: English
• ISSNs: 0958-0670

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>It has been hypothesized that exercise‐induced changes in metabolites and ions are crucial in the adaptation of contracting muscle. We tested this hypothesis by comparing adaptations to two different interval‐training protocols (differing only in the rest duration between intervals), which provoked different perturbations in muscle metabolites and acid–base status. Prior to and immediately after training, 12 women performed the following tests: (1) a graded exercise test to determine peak oxygen uptake (<inline-graphic xlink:href="ark:/27927/pgg1n1hf892" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" />); (2) a high‐intensity exercise bout (followed 60 s later by a repeated‐sprint‐ability test; and (3) a repeat of the high‐intensity exercise bout alone with muscle biopsies pre‐exercise, immediately postexercise and after 60 s of recovery. Subjects performed 5 weeks (3 days per week) of training, with either a short (1 min; HIT‐1) or a long rest period (3 min; HIT‐3) between intervals; training intensity and volume were matched. Muscle [H<sup>+</sup>] (155 ± 15 <italic>versus</italic> 125 ± 8 nmol l<sup>−1</sup>; <italic>P</italic> < 0.05) and muscle lactate content (84.2 ± 7.9 <italic>versus</italic> 46.9 ± 3.1 mmol (g wet weight)<sup>−1</sup>) were both higher after HIT‐1, while muscle phosphocreatine (PCr) content (52.8 ± 8.3 <italic>versus</italic> 63.4 ± 9.8 mmol (g wet weight)<sup>−1</sup>) was lower. There were no significant differences between the two groups regarding the increases in <inline-graphic xlink:href="ark:/27927/pgg1n1hf8nk" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" />, repeated‐sprint performance or muscle Na<sup>+</sup>, K<sup>+</sup>‐ATPase content. Following training, both groups had a significant decrease in postexercise muscle [H<sup>+</sup>] and lactate content, but not postexercise ATP or PCr. Postexercise PCr resynthesis increased following both training methods. In conclusion, intense interval training results in marked improvements in muscle Na<sup>+</sup>, K<sup>+</sup>‐ATPase content, PCr resynthesis and <inline-graphic xlink:href="ark:/27927/pgg1n1hf8ss" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" />. However, manipulation of the rest period during intense interval training did not affect these changes.</p> </abstract>