High-intensity interval training increases in vivo oxidative capacity with no effect on P(i)→ATP rate in resting human muscle.

  • Larsen R
  • Befroy D
  • Kent-Braun J
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Mitochondrial ATP production is vital for meeting cellular energy demand at rest and during periods of high ATP turnover. We hypothesized that high-intensity interval training (HIT) would increase ATP flux in resting muscle (VPi→ATP) in response to a single bout of exercise, whereas changes in the capacity for oxidative ATP production (Vmax) would require repeated bouts. Eight untrained men (27 ± 4 yr; peak oxygen uptake = 36 ± 4 ml·kg(-1)·min(-1)) performed six sessions of HIT (4-6 × 30-s bouts of all-out cycling with 4-min recovery). After standardized meals and a 10-h fast, VPi→ATP and Vmax of the vastus lateralis muscle were measured using phosphorus magnetic resonance spectroscopy at 4 Tesla. Measurements were obtained at baseline, 15 h after the first training session, and 15 h after completion of the sixth session. VPi→ATP was determined from the unidirectional flux between Pi and ATP, using the saturation transfer technique. The rate of phosphocreatine recovery (kPCr) following a maximal contraction was used to calculate Vmax. While kPCr and Vmax were unchanged after a single session of HIT, completion of six training sessions resulted in a ∼14% increase in muscle oxidative capacity (P ≤ 0.004). In contrast, neither a single nor six training sessions altered VPi→ATP (P = 0.74). This novel analysis of resting and maximal high-energy phosphate kinetics in vivo in response to HIT provides evidence that distinct aspects of human skeletal muscle metabolism respond differently to this type of training.

Author-supplied keywords

  • Adenosine Triphosphate
  • Adenosine Triphosphate: metabolism
  • Adult
  • Bicycling
  • Bicycling: physiology
  • Biological
  • Energy Metabolism
  • Energy Metabolism: physiology
  • Exercise
  • Exercise: physiology
  • Humans
  • Hydrogen-Ion Concentration
  • Magnetic Resonance Spectroscopy
  • Male
  • Mitochondria
  • Mitochondria: metabolism
  • Models
  • Muscle
  • Muscle Contraction
  • Muscle Contraction: physiology
  • Oxygen Consumption
  • Oxygen Consumption: physiology
  • Phosphates
  • Phosphates: metabolism
  • Rest
  • Rest: physiology
  • Skeletal
  • Skeletal: metabolism
  • Skeletal: physiology
  • Young Adult
  • ab_31P
  • ab_AGIR

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  • Ryan G Larsen

  • Douglas E Befroy

  • Jane a Kent-Braun

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