Effects of muscle glycogen depletion on some metabolic and physiological responses to submaximal treadmill exercise.
Abstract: The aim of this study was to investigate the effects of reduced muscle glycogen concentration on some physiological and metabolic responses during moderate intensity treadmill exercise in horses. Six Thoroughbred geldings were randomly allocated to 2 treatments (protocols A and B) or control in a 3 x 3 replicated Latin square design. In protocol A, horses performed low intensity exercise while horses in protocol B performed short bursts of high intensity exercise. Protocol A was designed to induce glycogen depletion mainly of slow twitch muscle fibers while protocol B aimed to deplete mainly fast twitch muscle fibers. Horses in the control group did not undergo exercise prior to the exercise test. Five hours after glycogen depletion, horses performed treadmill exercise at 60% VO2max at a treadmill slope of 10% until fatigue (20-30 min). The induced glycogen depletion prior to exercise had no significant effect on plasma glucose, insulin, or lactate concentrations during the exercise test, and there was no effect on glycogen utilization rate, although respiratory exchange ratios were lower in the glycogen-depleted groups. The VO2, heart rate and central blood temperature did not vary significantly between the protocols A and B and control throughout the exercise test. It was concluded that 20-30% depletion of glycogen concentration in the middle gluteal muscle resulted in a shift towards fat metabolism, but does not significantly affect heart rate, oxygen uptake, or concentrations of plasma glucose and lactate during moderate intensity exercise.
Publication Date: 1999-10-26 PubMed ID: 10534002PubMed Central: PMC1189559
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article investigates how lowering glycogen levels in muscle affects certain metabolic and physiological reactions during moderate-intensity exercise performed on a treadmill by horses. The study concludes that a 20-30% decrease in glycogen concentration results in a shift towards fat metabolism but does not significantly alter heart rate, oxygen uptake, or levels of plasma glucose and lactate during exercise of moderate intensity.
Study Design and Methods
- The study involved six Thoroughbred geldings which were assigned randomly to two treatments (protocols A and B) or a control group based on a 3 x 3 replicated Latin square design.
- Protocol A consisted of low-intensity exercise designed to majorly deplete glycogen in slow-twitch muscle fibers.
- Protocol B involved short, high-intensity exercise segments with the aim of primarily depleting glycogen in the fast-twitch muscle fibers.
- Horses in the control group didn’t perform any exercise prior to the exercise test.
- Following glycogen depletion, all the horses were subjected to treadmill activity at 60% of their maximal oxygen consumption with a treadmill slope of 10% until they showed signs of fatigue (usually between 20-30 minutes).
Study Findings
- Glycogen depletion did not significantly influence plasma glucose, insulin, or lactate levels during the exercise test.
- There was no noticeable effect on the rate at which glycogen is utilized.
- Respiratory exchange ratios were slightly lowered in the groups with glycogen depletion.
- Oxygen uptake (VO2), heart rate, and central blood temperature showed no significant differences between protocols A and B, and the control throughout the duration of the exercise test.
Conclusion
- A depletion of 20-30% in glycogen concentration in the middle gluteal muscle leads to an increased reliance on fat metabolism.
- However, this depletion does not significantly impact heart rate, oxygen uptake, or plasma glucose and lactate levels during moderate-intensity exercise.
Cite This Article
APA
Davie AJ, Evans DL, Hodgson DR, Rose RJ.
(1999).
Effects of muscle glycogen depletion on some metabolic and physiological responses to submaximal treadmill exercise.
Can J Vet Res, 63(4), 241-247.
Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, The University of Sydney, New South Wales, Australia. adavie@scu.edu.au
MeSH Terms
- Animals
- Blood Glucose
- Exercise Test
- Fats / metabolism
- Glycogen / metabolism
- Heart Rate
- Horses / physiology
- Lactic Acid / blood
- Male
- Muscle Fatigue / physiology
- Muscle, Skeletal / physiology
- Oxygen Consumption
- Physical Conditioning, Animal / physiology
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Citations
This article has been cited 1 times.- Mukai K, Ohmura H, Takahashi Y, Kitaoka Y, Takahashi T. Four weeks of high-intensity training in moderate, but not mild hypoxia improves performance and running economy more than normoxic training in horses. Physiol Rep 2021 Feb;9(4):e14760.
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