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Related Concept Videos

Metabolic States of the Body: The Postabsorptive State01:18

Metabolic States of the Body: The Postabsorptive State

The postabsorptive state usually starts about four hours after a meal and lasts until the next meal is eaten. During this time, the digestive system stops absorbing nutrients, and the body uses stored energy reserves to maintain stable blood glucose levels.
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
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Metabolic States of the Body: Fasting and Starvation

During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...
Muscle Recovery and Fatigue01:24

Muscle Recovery and Fatigue

Muscle fatigue refers to the decline in a muscle's ability to maintain the force of contraction after prolonged activity. It primarily stems from changes within muscle fibers. Even before experiencing muscle fatigue, one may feel tired and have the urge to stop the activity. This response, known as central fatigue, occurs due to changes in the central nervous system, namely the brain and spinal cord. While there is no single mechanism that induces fatigue, it may serve as a protective response...
Glucose Homeostasis: Regulation of Blood Glucose01:02

Glucose Homeostasis: Regulation of Blood Glucose

Carbohydrates consumed through foods are converted into glucose, a crucial energy source for the body. In the prandial state, high blood glucose levels stimulate the secretion of insulin from the pancreas. Insulin inhibits hepatic glucose production and stimulates glucose uptake and metabolism by muscle and adipose tissue. The excess glucose is converted into glycogen and stored in the liver and muscles.
During fasting, when blood glucose levels are low, the pancreas secretes glucagon. it...
Hypoglycemia and Glucagon01:15

Hypoglycemia and Glucagon

Without prolonged fasting, healthy individuals maintain blood glucose levels above 3.5 mM due to a well-adapted neuroendocrine counterregulatory system that effectively prevents acute hypoglycemia, a potentially life-threatening condition. The primary clinical scenarios for hypoglycemia encompass diabetes treatment, inappropriate production of endogenous insulin or insulin-like substances by tumors, and the use of glucose-lowering agents in non-diabetic individuals. Notably, hypoglycemia in the...
Hypoglycemia01:26

Hypoglycemia

Hypoglycemia is a blood glucose level below 70 mg/dL. It commonly occurs in individuals using insulin or insulin-secreting drugs, but may also arise in non-diabetic conditions. People with type 1 diabetes are at the highest risk because they depend on exogenous insulin. People with type 2 diabetes are also at risk, especially when treated with insulin or medications such as sulfonylureas, which increase insulin release regardless of blood glucose levels. It develops when insulin levels exceed...

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Quantification of Subcellular Glycogen Distribution in Skeletal Muscle Fibers using Transmission Electron Microscopy
08:32

Quantification of Subcellular Glycogen Distribution in Skeletal Muscle Fibers using Transmission Electron Microscopy

Published on: February 7, 2022

Brain glycogen decreases during prolonged exercise.

Takashi Matsui1, Shingo Soya, Masahiro Okamoto

  • 1Laboratory of Exercise Biochemistry and Neuroendocrinology, University of Tsukuba Graduate School of Comprehensive Human Sciences, Tsukuba, Ibaraki, Japan.

The Journal of Physiology
|April 28, 2011
PubMed
Summary

Prolonged exercise depletes brain glycogen, especially during hypoglycemia. Increased monoamines correlate with reduced brain glycogen, offering insights into central fatigue during exhaustive exercise.

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Last Updated: Jun 2, 2026

Quantification of Subcellular Glycogen Distribution in Skeletal Muscle Fibers using Transmission Electron Microscopy
08:32

Quantification of Subcellular Glycogen Distribution in Skeletal Muscle Fibers using Transmission Electron Microscopy

Published on: February 7, 2022

Biochemical Titration of Glycogen In vitro
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Measurement of Insulin- and Contraction-Stimulated Glucose Uptake in Isolated and Incubated Mature Skeletal Muscle from Mice
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Published on: May 16, 2021

Area of Science:

  • Neuroscience
  • Exercise Physiology
  • Biochemistry

Background:

  • Brain glycogen serves as an energy reserve during low blood glucose (hypoglycemia).
  • Hypoglycemia during exhaustive exercise may reduce brain glycogen, but this remains untested.

Purpose of the Study:

  • To test if prolonged exercise decreases brain glycogen levels.
  • To investigate the role of brain monoamines in reduced brain glycogen during exercise.

Main Methods:

  • Male Wistar rats exercised on a treadmill for 30-120 minutes at moderate intensity.
  • Brain glycogen levels measured using high-power microwave irradiation.
  • Blood and brain glucose levels, and cortical monoamine metabolites (MHPG, 5-HIAA) analyzed.

Main Results:

  • Brain glycogen remained stable for 30-60 minutes but decreased significantly (37-60%) after 120 minutes of exercise.
  • Decreased brain glycogen correlated positively with blood and brain glucose levels.
  • Cortical MHPG and 5-HIAA increased during prolonged exercise, correlating negatively with glycogen levels.

Conclusions:

  • Prolonged exhaustive exercise leads to a decrease in brain glycogen.
  • Hypoglycemia and increased brain monoamines are associated with decreased brain glycogen, contributing to central fatigue.