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Short‐term, high‐intensity interval training (HIT) alters ATP pathway fluxes during maximal muscle contractions in humans
Author(s) -
Larsen Ryan Godsk,
Maynard Logan,
KentBraun Jane
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb567
Subject(s) - bioenergetics , oxidative phosphorylation , glycolysis , anaerobic exercise , atp synthase , isometric exercise , phosphocreatine , medicine , chemistry , adenosine triphosphate , endocrinology , cycling , zoology , metabolism , energy metabolism , biology , physical therapy , mitochondrion , biochemistry , enzyme , archaeology , history
Phosphorus magnetic resonance spectroscopy (MRS) was used to examine the effects of 2 weeks of cycling training on bioenergetics of vastus lateralis in vivo. Eight healthy, untrained men (27 ± 4 yr) performed 6 sessions of HIT (4–6 bouts of 30‐s all‐out cycling). At baseline, and after the 1 st and the 6 th training sessions, rates of ATP synthesis from net PCr breakdown (ATP CK ), glycolysis (ATP GLY ) and oxidative phosphorylation (ATP OX ) were measured during a 24‐s maximal voluntary isometric contraction (MVIC) in a 4T magnet. Training increased peak whole‐body oxygen uptake (36 ± 4 to 39 ± 5ml·kg −1 ·min −1 , p=0.01) and exercise capacity (225 ± 32 to 239 ± 36 W, p=0.04) on the cycle ergometer, with no effects on total ATP production or force‐time integral during the MVIC. While ATP production through the 3 pathways remained unchanged after the first training session, 6 training sessions increased the relative contribution of ATP OX (31 ± 2 vs. 39 ± 2% of total ATP turnover, p<0.001), and lowered the relative contribution from ATP CK (49 ± 2 vs. 44 ± 1%, p=0.004) and ATP GLY (20 ± 2 vs. 17 ± 1%, p=0.03). Thus, 6 sessions of HIT alters muscle energetics, such that maximal contractions are performed with increased support from oxidative ATP synthesis and relatively less contribution from anaerobic ATP production, which may contribute to improved exercise capacity. Support: NIH K02 AG023582