Related Experiment Video
Updated: Aug 17, 2026

Application of Chronic Stimulation to Study Contractile Activity-induced Rat Skeletal Muscle Phenotypic Adaptations
Published on: January 25, 2018
Cellular adaptation of the trapezius muscle in strength-trained athletes
F Kadi1, A Eriksson, S Holmner
1Department of Anatomy, Umeå University, Sweden.
Abstract:
The aim of this study was to elucidate the cellular events that occur in the trapezius muscle following several years of strength training. In muscle biopsies from ten elite power lifters (PL) and six control subjects (C), several parameters were studied: cross-sectional area of muscle fibres, myosin heavy chain composition (MHC) and capillary supply [capillaries around fibres (CAF) and CAF/fibre area]. A method was also developed for counting the number of myonuclei and satellite cell nuclei. The proportion of fibres expressing MHC IIA, the cross-sectional area of each fibre type and the number of myonuclei, satellite cells and fibres expressing markers for early myogenesis were significantly higher in PL than in C (P<0.05). A significant correlation between the myonuclear number and the cross-sectional area was observed. Since myonuclei in mature muscle fibres are not able to divide, we suggest that the incorporation of satellite cell nuclei into muscle fibres resulted in the maintenance of a constant nuclear to cytoplasmic ratio. The presence of small diameter fibres expressing markers for early myogenesis indicates the formation of new muscle fibres.
More Related Videos
Related Concept Videos
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...
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...
Muscles of the Anterior Neck
Muscles of the Shoulder
Anterior Thoracic Muscles
The anterior thoracic muscles include the serratus anterior, subclavius, and...
Cellular Adaptation I: Introduction and Atrophy
Cellular Adaptation II: Hypertrophy

