Various factors can result in myalgia which is commonly known as muscle pain. It is important to understand how the muscle pain originated to make it easier to treat and relieve any discomfort.
Muscle tissue is made up of millions of individual muscle cells termed sarcomeres. The purpose of these sarcomeres is to lengthen and contract so that the skeleton can move. At the ends of sarcomeres are Z-discs which are the terminals of muscle cells. When you exercise muscle cells pull on these terminals and if done enough times with sufficient strain, it will lead to damage to the Z-discs and muscle cells as a unit. This type of microdamage is necessary to get bigger, and stronger muscles. Muscle cells need to go through this process of stress through exercise and also a time of recovery to be able to grow back bigger. This damage on a microscopic level led to inflammation and muscle soreness. This soreness is not a result of lactic acid, because lactic acid dissociates in less than a few seconds to produce lactate. [1] Studies have also found that blood lactate levels quickly return to pre-exercise levels after an intense workout long before soreness sets in.
A lot of individuals experience muscle pain during or directly after strenuous exercise which feels like a burning sensation in a localized area of muscle tissue. This pain generally dissipates directly after a
workout. The cause of this type of pain is a strongly contracted isometric muscle. [2] In simpler terms, this is when a muscle is kept under tension in a stationary position. During the isometric contraction of a muscle, the blood vessels carrying oxygen and sources of energy are constricted. With insufficient amounts of oxygen being transported to the working muscle tissue, it will start relying on anaerobic (without oxygen) pathways for energy production. The waste products of this anaerobic pathway lead to acidosis which is the build-up of excess acidic compounds in bodily fluids. This acidic environment triggers the pain receptors in muscle tissue that is quite sensitive towards an increasingly acidic environment. This then results in the pain and burning sensation experienced. As soon as the isometric contraction ends, blood flow through the muscle tissue increases and flushes all the acidic metabolites out resulting in the pain dissipating. [2]
Delayed onset muscle soreness or DOMS is another type of muscle pain linked to exercise. It is generally experienced 24 to 72 hours after exercising. Pain and discomfort of this type are generally experienced when beginning a new type of exercise or after being out of exercise for a while. DOMS is a result of eccentric muscle contractions (muscle tissue elongating under tension). During this type of contraction greater mechanical stress is placed on muscle tissue leading to micro-tears in the tissue. This leads to inflammation, weakness, tenderness, and pain in the muscles worked. [2]
Muscle cramps are involuntary intense muscle spasms that have no exact or fully understood the cause.
There are two theories as to why muscle cramps could occur. The first is an electrolyte imbalance that is associated with changes in muscle temperature along with dehydration that affects electrolyte levels such as sodium within the body. Sodium can make the neuromuscular junction more excitable which leads to spontaneous intense muscle contractions. This can be treated by ingesting fluids and salt solutions, massaging the muscle and cold treatment. [2] The second theory is that muscle cramps are caused by altered neuromuscular control that results in the increased firing of motor neurons. The involuntary firing of motor neurons results in muscles that cramp.
If muscle pain lasts for longer than a few days, consult with your healthcare practitioner.
