Biological Mechanisms Behind Recovery
Introduction:
If you are an athlete, you likely have dealt with annoying injuries before. But, have you ever wondered what actually goes on inside the body as it prepares you for exercise again? There are many injury types, but for convenience's sake let’s focus on the most prominent of muscle injuries, soreness and tears.
Stage 1 - Destruction:
The first stage is the injury itself. This can be caused by strains, usually overstretching the muscle, or contusions, which are direct forces exerted on the muscle that cause injury. Excessive strain from overtraining or high-intensity activity is the biggest contributor, especially in sports requiring explosive movements like football. Muscle fibers tear and release inflammatory cells into the injured area for both outcomes. These inflammatory cells secrete growth factors and cytokines for the later stages, usually taking a few days, wherein physical therapists recommend braces, crutches, or other forms of movement restriction. The body simultaneously begins its defensive actions, producing a barrier to prevent the destruction and repair processes from spreading to non-injury areas.
Stage 2 - Repair:
The second stage consists of the body’s defense system when inflammation and swelling occur. Three key types of cells are involved: macrophages, satellite cells, and fibroblasts. The macrophages act as janitors, eating dead tissue in injured regions. Satellite cells, on the other hand, are stem cells that undergo differentiation–the biological process of a cell undergoing changes to specialize–into myoblasts. They are normally silent and are rapidly activated from a resting state.
Myoblasts are the cells that group into new muscle fibers. They are also thought to proliferate and combine with existing muscle fibers to regenerate tissue. Fibroblasts additionally form new connective tissue that fills in the hole from the injury and forms a scar. Depending on severity, the repairing phase can take from a week to months. As for treatment, this is the point where strength training exercises or gentle movement can begin, as returning to previous activity levels can result in re-injury if not careful.
Stage 3 - Remodeling
The longest phase, also sometimes called the maturation phase, is thought to be concurrent with the second stage. This is when new connective tissue and myoblast groups mature and become the final tissue, kept until another injury in the area occurs. The maturing is equivalent to the differentiation of satellite cells, which is promoted by IGF–a growth factor. Sometimes, further treatment is done to make sure this tissue aligns in parallel lines rather than in a random orientation like normally. From that point, the full function should be restored as soon as the last bits of tissue injury components are broken down. From there, any remaining biomechanical deficits are fixed, and training can resume. It will take many more weeks or months to recover to pre-injury levels of strength, so athletes should always take caution and follow medical guidance during this stage.
Conclusion:
Understanding how muscles heal is vital to athletes and doctors alike, as muscles make up 40-45% of the body's mass and constitute 55% of all sports injuries. This article briefly took us through the body's recovery steps; however, the body's processes are infinitely more complicated, with hundreds of genes and more parts of the muscle to consider. Nevertheless, the costs of training lost during injury time still mean that playing safe and listening to the body is important.
Sources:
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Hidaya Aliouche, B.Sc. “How Do Muscles Repair Themselves after Injury?” News, 11 Jan. 2022, www.news-medical.net/health/How-Do-Muscles-Repair-Themselves-After-Injury.aspx.
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