Related Experiment Video
Updated: Aug 7, 2026

Fiber Type Identification of Human Skeletal Muscle
Published on: September 22, 2023
Characteristics of skeletal muscle in competitive cyclists
Abstract:
Muscle samples from the vastus lateralis and maximal oxygen uptakes were obtained from 22 male and 7 female competitive cyclists. 19 untrained males, and 10 untrained females. Eleven of the 22 male cyclists were designated elite cyclists (Group A) on the basis of their success in national and/or international competition. The remaining 11 male cyclists (Group B) were also trained but had not achieved the same level of competitive success. Significant mean differences (P less than 0.05) between Groups A and B were found for VO2 max (67 and 57 ml/kg/min), malate dehydrogenase (MDH) and phosphorylase (PH), in biopsied muscle. No differences were evident between Groups A and B for % slow twitch (ST) and % fast twitch (FT) fibers, or in area FT or ST. Nor was there any difference in the mean activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) between the groups. Significant correlations were found between VO2 max and SDH, VO2 max and MDH, and between SDH and MDH. These data also indicate that an extremely high percentage of FT or ST fibers may not be a requirement for success in competitive cycling as has been found in earlier studies on sprint or endurance running.
More Related Videos
08:12Intact Short, Intermediate, and Long Skeletal Muscle Fibers Obtained by Enzymatic Dissociation of Six Hindlimb Muscles of Mice: Beyond Flexor Digitorum Brevis
Published on: December 1, 2023
07:01Single Fiber Isolation Assay for the Assessment of Oxidative Myofiber Behavior
Published on: March 31, 2026
Related Concept Videos
Classification of Skeletal Muscle Fibers
Slow-Twitch Muscle Fibers
Slow oxidative, muscle fibers appear red due to large numbers of capillaries and high levels of...
Microscopic Anatomy of Skeletal Muscles
The muscle sarcolemma is a plasma membrane enclosing each muscle cell that conducts electrical signals called action potentials. The sarcolemma extends into the cell to form T-tubules, ensuring the neural impulses are uniformly distributed across the entire muscle...
Energy Supply for Muscle Contraction
Types of Skeletal Muscle Fibers
Fast-twitch fibers
Fast-twitch fibers, or Type II fibers, are designed for quick, powerful bursts of speed and strength. They reach peak tension within approximately 0.01 seconds following stimulation. Characterized by a large diameter and densely packed myofibrils, these fibers contain...
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...
Specialized Characteristics of Cardiac Muscles
Cardiac muscle cells are smaller than skeletal muscles, averaging 10–20 mm in diameter and 50–100 mm in length. However, they have large energy demands for continuous contraction and relaxation. This energy is almost exclusively derived from aerobic metabolism of energy reserves in...