Altering the rest interval during high‐intensity interval training does not affect muscle or performance adaptations

Abstract

New Findings r What is the central question of this study?Are exercise-induced changes in metabolites and ions a crucial factor in the adaptation of contracting muscle? This was assessed by manipulating the rest period between high-intensity intervals. r What is the main finding and its importance?Our results suggest that the perturbation of muscle metabolites (specifically phophocreatine, lactate and H + ) during high-intensity interval training is not a crucial factor regulating related adaptations of the contracting muscle, when training intensity and volume are matched. This has implications for understanding the mechanisms that regulate muscle adaptations.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 O 2 peak ); (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 inV O 2 peak , repeatedsprint performance or muscle Na . Altered concentrations of these metabolites and ions have been implicated in the multifactorial process of muscle fatigue, owing to their effects on muscle enzyme activity, sarcoplasmic reticulum Ca 2+ release and cellular membrane excitability (Allen et al. 2008;. The restoration of perturbed metabolite and ion concentrations towards resting levels following intense muscle contractions is likely to be important for the recovery of subsequent exercise performance. In support of this, the resynthesis of PCr has been related to the recovery of force output during repeated sprints (Bogdanis et al. 1996), and the PCr resynthesis rate is elevated in trained compared with untrained muscle . Therefore, improving the capacity to minimize exercise-induced disturbances in these metabolites and ions during high-intensity exercise, as well as maximizing their rate of recovery, may be important to enhance performance.Training induces many adaptations within skeletal muscle that minimize these metabolic and ionic distur...

Perceptual Changes in Response to Two Regimens of Interval Training in Sedentary Women

“…Previous data (16) revealed no differences in adaptations to interval training whether recovery between bouts was relatively brief or prolonged, so the dissimilar recovery duration seems to elicit minimal effects on our findings. Sessions began with a 4-minute warm-up at 40 W followed by 6-10 bouts of HIIT.…”

“…In contrast, many studies have examined changes in these variables during acute exercise including HIT. One study (6) revealed significant increases in RPE ( 14), peaking at values equal to 7.0 (very hard) in response to Wingate-based SIT, similar to values equal to 16-18 on the 15-point Borg scale (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)23) in response to treadmill interval training (47). In a recent study, Oliveira et al (39) required healthy men to perform treadmill exercise at 72%V _ O 2 max and interval training at 100%V _ O 2 max which were matched for average intensity and duration.…”

“…RPE responses(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)23) to different intensities of interval training during acute interval training (across) and in response to chronic training (down; mean 6 SD). *…”

High Intensity Interval Training in a Real World Setting: A Randomized Controlled Feasibility Study in Overweight Inactive Adults, Measuring Change in Maximal Oxygen Uptake

“…This was in part because the recovery phase of the interval training (3 minutes) was quite long. It may be possible to shorten the rest interval without any loss in fitness [30]. Another feature of the overall study design, incorporated to reflect best practice, was a warm up and cool down period totaling 15 minutes per exercise session.…”

Exercise-induced metabolic fluctuations influence AMPK, p38-MAPK and CaMKII phosphorylation in human skeletal muscle

“…Despite this, the consequences, maximal oxygen consumption, and training effects were not different with either a short or longer rest period during interval training (Edge et al. 2013). Whether the metabolic fluctuations per se could activate in itself the signaling cascades leading to PGC-1 α is unknown.…”