Related Experiment Video
Updated: Jul 29, 2026

Human Skeletal Muscle Biopsy Procedures Using the Modified Bergström Technique
Published on: September 10, 2014
No change in insulin mediators in human skeletal muscle during isometric contraction or recovery
1Department of Surgical Sciences, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden.
Abstract:
The rapid activation of glycogen synthase in human skeletal muscle during recovery from isometric contraction is dependent on an intact circulation, which suggests the requirement of an activating humoral factor. To determine whether the activating factor is insulin, muscle biopsies were obtained from subjects at rest, at fatigue, 3 min postexercise with an intact circulation, and 3 min postexercise during which circulation to the muscle was occluded. Two inositol phosphoglycan mediators of insulin action were isolated from the biopsies, and bioactivity was measured by determining the effects of the isolated mediators on the activities of purified cyclic AMP-dependent protein kinase, pyruvate dehydrogenase phosphatase and glycogen synthase phosphatase in vitro. Bioactivity was not altered by any condition compared with rest. These data suggest that changes in inositol phosphoglycans are not responsible for the circulation-dependent activation of glycogen synthase during recovery from exercise.
More Related Videos
Related Concept Videos
Relaxation of Skeletal Muscles
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Muscle Recovery and Fatigue
Isotonic and Isometric Muscle Contractions
Isotonic contractions
Isotonic contractions occur when a muscle changes length while the...
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Smooth Muscle Contraction
The onset of contraction is triggered by an increase in calcium ions within the sarcoplasm, similar to the process in striated muscle. However, smooth muscles have a relatively smaller reservoir of the sarcoplasmic...
Alterations in Muscle Tone lll

