Abstract
Purpose: The purpose of the present study was to evaluate whole-muscle content of several proteins involved in the regulation of skeletal muscle mitochondrial protein content and anaerobic capacity following 4 weeks of extremely low-volume high-intensity interval training (HIT). Methods: Young, healthy, recreationally active adult males (n = 8) trained 4 times a week for 4 weeks on a cycle ergometer. Each session involved 4 min of total exercise comprised of eight 20 s intervals at ~170% of peak aerobic power separated by 10 s rest. Muscle biopsies were taken prior to (pre) and ~72 hrs post-training (post). Par- ticipants completed an incremental peak oxygen up- take (VO2peak) test and a Wingate test pre-, mid-, and post-training. Results: VO2peak was elevated (p p -1·min-1, mid: 43.4 ± 2.5 ml·kg-1·min-1, post-: 47.2 ± 2.9 ml·kg-1·min-1). Wingate mean power also increased with training (pre-: 701.0 ± 73.0 W, mid-: 745.5 ± 73.3 W, post-: 786.8 ± 80.0 W). While maximal citrate synthase activity was unchanged, protein expression of the mitochondrial protein cytochrome c oxidase (COX) subunit I (+27%; p p p = 0.08) increased. Increases (p α (+19%), and nuclear PGC-1α (+46%) were also observed after 4 weeks of HIT. No changes were observed in the whole-muscle contents of PDHe1a, PDK4, SIRT1, mTOR, S6K1, MCT1, or PFK protein. Conclusions: These results demonstrate that several mitochondrial protein (but not citrate synthase activity), PGC-1α protein content, and exercise capacity can be improved in only 4 min of total training time per day, 4 days per wk using HIT cycle training.
Highlights
Improved exercise tolerance and increases in mitochondrial protein in skeletal muscle have been demonstrated following high-intensity interval training (HIT) [1,2]
The purpose of this study was twofold: 1) to confirm the rapid improvements in aerobic and anaerobic capacity previously observed following extremely low-volume HIT utilizing the Tabata protocol; and 2) to examine changes in markers of skeletal muscle mitochondrial protein, proteins involved in the regulation of mitochondrial biogenesis, and protein associated with skeletal muscle glycolytic capacity
This study evaluated changes in potential intramuscular mechanisms associated with increase in aerobic and anaerobic capacity induced by 4 wks of extremely lowvolume high-intensity cycling exercise
Summary
Improved exercise tolerance and increases in mitochondrial protein in skeletal muscle have been demonstrated following high-intensity interval training (HIT) [1,2]. The available evidence suggests that increases in exercise tolerance and mitochondrial protein following short-term endurance training and HIT are similar [1,3,4]. The HIT protocol presented by Tabata et al (1996), subsequently termed the “Tabata protocol”, consists of eight 20 s intervals at ~170% of maximal aerobic power separated by 10 s of rest. This extremely low-volume protocol totals less than 3 min of exercise time and only 4 min total training commitment per training session. In humans, training with this protocol improves both aerobic and anaerobic exercise capacity, and muscle endur-
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