title: Altering the rest interval during high-intensity interval training does not affect muscle or performance adaptations.
abstract: 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 (V(O2)); (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(+)] (155 ± 15 versus 125 ± 8 nmol l(-1); P < 0.05) and muscle lactate content (84.2 ± 7.9 versus 46.9 ± 3.1 mmol (g wet weight)(-1)) were both higher after HIT-1, while muscle phosphocreatine (PCr) content (52.8 ± 8.3 versus 63.4 ± 9.8 mmol (g wet weight)(-1)) was lower. There were no significant differences between the two groups regarding the increases in , repeated-sprint performance or muscle Na(+),K(+)-ATPase content. Following training, both groups had a significant decrease in postexercise muscle [H(+)] 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(+),K(+)-ATPase content, PCr resynthesis and . However, manipulation of the rest period during intense interval training did not affect these changes.
authors.affiliation: Muscle Metabolism Laboratory, Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand
authors.forename: Johann
authors.initials: J
authors.lastname: Edge
authors.forename: Nir
authors.initials: N
authors.lastname: Eynon
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKenna
authors.forename: Craig A
authors.initials: CA
authors.lastname: Goodman
authors.forename: Roger C
authors.initials: RC
authors.lastname: Harris
authors.forename: David J
authors.initials: DJ
authors.lastname: Bishop
mesh_terms: D000136:Acid-Base Equilibrium; D000222:Adaptation, Physiological; D000293:Adolescent; D000704:Analysis of Variance; D001639:Bicarbonates / Q000378:metabolism; D001706:Biopsy; D002336:Carnosine / Q000378:metabolism; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D009119:Muscle Contraction; D010101:Oxygen Consumption; D010725:Phosphocreatine / Q000378:metabolism; D052097:Quadriceps Muscle / Q000378:metabolism*; D012146:Rest; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013997:Time Factors; D014904:Western Australia; D055815:Young Adult
chemical_list: D001639:Bicarbonates; D010725:Phosphocreatine; D019344:Lactic Acid; D002336:Carnosine; D000254:Sodium-Potassium-Exchanging ATPase