Exercise is an essential aspect of keeping your body healthy and increasing your length and quality of life. The American College of Sports Medicine suggests that you include at least 150 minutes of exercise into your week. Although exercise provides multiple benefits for your body, it can produce temporary side effects, such as muscle weakness and soreness.
Lactic Acid Theory
Lactic acid is one of the first substances that is often connected to theories of why you experience muscle weakness or fatigue after exercise. Lactic acid is produced by the anaerobic breakdown of glycogen for energy during exercise. The buildup of lactic acid has long been believed to weaken the muscles by interrupting proteins responsible for muscle contraction. As new research has surfaced, this theory has slowly become discredited, suggests Dr. Andrew Marks from Columbia University.
Calcium Theory
New research from the physiologists at Columbia University Medical Center suggests that muscle weakness and fatigue actually may be caused by the leaking of calcium from your muscle cells. Calcium plays an integral role in muscle cells regarding the contraction of muscles during exercise. Particularly intense exercise can cause this calcium to leak from your cells, reducing the abilities of your muscles to contract. As the calcium leaks, it triggers the response of enzymes, which eat away at the muscle fibers and increase muscle weakness even further.
Hypertophy
Soreness is commonly attributed to muscle hypertrophy, or muscle building. This natural process occurs as exercise creates microscopic areas of damage to your muscle tissue. This damage causes the soreness often associated with exercise, especially if you are new to exercise or have not exercised in awhile. The damage activates special cells that migrate to the injured areas to both heal the injury sites, as well as build up the muscle fibers to prevent injury in the future. As the area heals, the soreness subsides.
Injury
Severe soreness or pain can be associated with injuries. Three main tissues are particularly prone to injury during exercise -- muscles, tendons and ligaments. These tissue are designed only to stretch so far, and when pulled or stretched past their limits, strains, sprains or tears can occur. Depending on how severe the injury is, as well as how bad the soreness or pain develops, you may need to see a doctor for a more thorough evaluation and treatment.
References
- American College of Sports Medicine: Activity Guidelines.
- Science Week; Physiology -- Lactic Acid and Muscle Performance; D. Allen and H. Westerblad; 2004
- BodyBuilding.com: All About Muscle Fatigue
- New York Times; Finding May Solve Riddle of Fatigue in Muscles; Gina Kolata; February, 2008
- Science Daily; Leaky Muscle Cells Lead To Fatigue; February, 2008
- Dr. Mirkin; What Causes Muscle Soreness?; Gabe Mirkin, M.D.
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