Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Substrate metabolism when subjects are fed carbohydrate during exercise.

J F Horowitz1, R Mora-Rodriguez, L O Byerley

  • 1The Human Performance Laboratory, Department of Kinesiology and Health Education and Division of Nutritional Sciences, The University of Texas at Austin, Austin, Texas 78712, USA.

The American Journal of Physiology
|May 18, 1999
PubMed
Summary

Carbohydrate ingestion during exercise suppresses lipolysis but does not limit fat oxidation. Fat oxidation reduction is linked to increased glucose uptake, not suppressed lipolysis, during prolonged exercise.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Role of pulsatile growth hormone (GH) secretion in the regulation of lipolysis in fasting humans.

Clinical diabetes and endocrinology·2022
Same author

Inflammation and metabolism gene sets in subcutaneous abdominal adipose tissue are altered 1 hour after exercise in adults with obesity.

Journal of applied physiology (Bethesda, Md. : 1985)·2021
Same author

Exercise improves metformin 72-h glucose control by reducing the frequency of hyperglycemic peaks.

Acta diabetologica·2020
Same author

Insulin sensitivity improvement with exercise training is mediated by body weight loss in subjects with metabolic syndrome.

Diabetes & metabolism·2019
Same author

Weight loss but not gains in cardiorespiratory fitness after exercise-training predicts improved health risk factors in metabolic syndrome.

Nutrition, metabolism, and cardiovascular diseases : NMCD·2018
Same author

Effects of intense aerobic exercise and/or antihypertensive medication in individuals with metabolic syndrome.

Scandinavian journal of medicine & science in sports·2018

Area of Science:

  • Exercise Physiology
  • Nutritional Biochemistry
  • Metabolic Regulation

Background:

  • Carbohydrate availability is crucial for endurance exercise performance.
  • The metabolic interplay between carbohydrate intake, lipolysis, and fat oxidation during exercise is complex.
  • Understanding these effects is vital for optimizing fueling strategies in athletes.

Purpose of the Study:

  • To investigate the impact of carbohydrate ingestion on lipolytic rate, plasma glucose disappearance (Rd Glc), and fat oxidation during low- and moderate-intensity exercise.
  • To determine if suppressed lipolysis limits fat oxidation following carbohydrate intake.
  • To examine the relationship between glucose uptake and fat oxidation during exercise with carbohydrate feeding.

Main Methods:

  • Six moderately trained men performed 2-hour cycling trials at 25% and 68% VO2 peak.

Related Experiment Videos

  • Subjects underwent four conditions: fed and fasted at each exercise intensity.
  • Carbohydrate (0.8 g/kg at 30 min, 0.4 g/kg at 60 & 90 min) was administered during fed trials.
  • Measurements included lipolysis, Rd Glc, and substrate oxidation rates.

    • Main Results:

    • During low-intensity exercise, carbohydrate feeding increased plasma insulin, suppressed lipolysis by 22%, but did not immediately affect fat oxidation.
    • Fat oxidation reduction occurred later (80-90 min) and correlated with increased Rd Glc.
    • Moderate-intensity exercise showed minimal insulin increase, slight lipolysis attenuation, but no significant changes in Rd Glc or fat oxidation when fed.
    • Lipolysis remained in excess of fat oxidation even with carbohydrate ingestion.

    Conclusions:

    • Carbohydrate ingestion during exercise, particularly at lower intensities, suppresses lipolysis but does not limit overall fat oxidation.
    • The reduction in fat oxidation during prolonged exercise with carbohydrate feeding is primarily associated with increased glucose uptake (Rd Glc), not suppressed lipolysis.
    • Lipolytic rate does not appear to be a limiting factor for fat oxidation under these feeding conditions.