Related Experiment Video
Updated: Jun 12, 2026
08:08
An in vivo Rodent Model of Contraction-induced Injury and Non-invasive Monitoring of Recovery
Published on: May 11, 2011
Morphophysiological Aspects of the Muscle Injury Caused by Eccentric Exercise
Mariana Baptista1, Isabella Gomes1, Matheus Bertanha Fior1
1Laboratory of Morphology and Physical Activity (LAMAF), Institute of Biosciences, São Paulo State University, 24A Avenue, 1515, Bela Vista, Rio Claro, São Paulo 13506-900, Brazil.
Summary
Eccentric exercise causes muscle injury, inflammation, and functional decline in rats. Regeneration begins with neutrophils and macrophages, indicating a complex healing process.
Area of Science:
- Exercise physiology
- Muscle biology
- Inflammation research
Background:
- Muscle injuries disrupt function through cellular damage and inflammation.
- Eccentric exercise is a validated model for inducing and studying muscle injury.
- Understanding muscle adaptations post-injury is crucial for recovery strategies.
Purpose of the Study:
- To investigate morphological, biochemical, and functional changes in rat muscle following an eccentric exercise-induced injury.
- To analyze the inflammatory response and tissue regeneration timeline.
Main Methods:
- Eccentric exercise protocol on a treadmill with a -16° incline.
- Functional assessments including grip strength and joint edema measurement.
- Histological analysis (Hematoxylin-Eosin, Picrosirius) and biochemical assays (ELISA for IL-6, IL-10, TNF-α).
Main Results:
- Eccentric exercise induced reduced body/muscle mass and grip strength.
- Elevated inflammatory markers (TNF-α, IL-6) at PI0H, increased joint edema at PI24H.
- Increased connective tissue at PI7D, with neutrophils at PI24H and macrophages at PI4D indicating regeneration.
Conclusions:
- The eccentric exercise protocol effectively induces muscle injury and inflammation.
- Muscle injury leads to functional deficits and increased connective tissue.
- Early regeneration involves neutrophil and macrophage infiltration, suggesting a phased healing response.
Related Concept Videos
01:26Cross-bridge Cycle
As muscle contracts, the overlap between the thin and thick filaments increases, decreasing the length of the sarcomere—the contractile unit of the muscle—using energy in the form of ATP. At the molecular level, this is a cyclic, multistep process that involves binding and hydrolysis of ATP, and movement of actin by myosin.
01:24Muscle 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...
01:20Motor Unit Stimulation
When the neuron of a motor unit fires an action potential, it triggers a series of events, leading to a twitch contraction in the muscle fibers. The process of excitation-contraction coupling is crucial in relaying the action potential to the muscle fibers.
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
01:28Disorders of the Skeletal Muscle
The clinical conditions affecting the skeletal muscle tissue are broadly categorized as musculoskeletal and neuromuscular disorders.
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
Musculoskeletal disorders
Musculoskeletal disorders involve injuries and conditions affecting the skeletal muscles and associated connective tissues. These disorders can arise from acute biomechanical stresses or chronic overuse and can occur across different age groups. Common injuries include sprains, fractures, and muscular strains, often resulting from...
01:27Exercise and Muscle Performance
Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
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...
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...
01:19Impact Loading
Impact loading occurs when a moving object collides with a stationary structure, such as a rod with a uniform cross-sectional area fixed at one end. Under these conditions, the rod absorbs the kinetic energy from the striking object, leading to deformation and subsequent stress development. As the rod returns to its original position and reaches maximum stress, the absorbed energy, initially manifested as kinetic energy, transforms entirely into strain energy.
In cases of elastic deformation,...
In cases of elastic deformation,...