Chronic muscle soreness is, quite literally, a pain to live with. Often, no amount of stretching, massage, heat, ice, or ibuprofen can provide much lasting relief.
To understand the cause of chronic muscle soreness, we need to start by examining what’s happening inside our muscles when they’re actively working. Our brain sends a message to our muscles saying, “We’re going running—time to get moving!” In response, our muscles begin contracting and releasing in a coordinated, nearly automatic pattern.
In order to contract, our muscles use adenosine triphosphate (ATP) as a source of energy. ATP is a molecule used by the body in numerous physiological functions, from muscular contraction to synthesizing DNA to perceiving taste. Because of its important role in so many processes, ATP is constantly being synthesized and consumed by our bodies in mass volumes.
Muscle fibers store only a few seconds’ worth of ATP, so almost immediately the body must start producing more of its energy source if it wants to keep moving. And as long as our brain continues to send the signal to keep running, our muscles will try their hardest to keep up. When muscles require more energy, the liver changes stored glycogen into glucose and sends it into the bloodstream. The glucose combines with oxygen to create ATP, and water, carbon dioxide and heat are released as waste products. This process, called aerobic metabolism or aerobic respiration, is why we breathe heavily when doing aerobic exercise; our bodies need that extra oxygen in order to produce energy for our muscles.
Sometimes, no matter how hard we breathe, we simply can’t take in enough oxygen to keep up with our muscles’ energy demands. When there is not enough oxygen being supplied, cells are forced to create energy through a far less efficient process called anaerobic metabolism. In this process, glucose is synthesized into ATP without the help of oxygen, and lactic acid is produced as waste.
As lactic acid is produced, the body quickly breaks it down into lactate and hydrogen ions. The lactate is carried by the blood back to the liver, where it is converted into glucose and either consumed as energy or stored as glycogen for future use. Likewise, the body efficiently takes care of the hydrogen ions with the bicarbonate buffering system. Bicarbonate combines with the hydrogen, forming carbonic acid, which is then converted into water and carbon dioxide. The carbon dioxide is exhaled by the lungs, contributing to our increased rate of breathing.
The only time we feel the negative effects of anaerobic metabolism is when we are exercising so hard that this recycling process can’t keep up. It is agreed that the dull ache and burning sensation we feel during strenuous exercise is a result of a buildup of hydrogen ions which activate pain receptors in our muscles. In addition, a variety of waste products increase the acidity in our muscles, making it difficult and sometimes impossible for the muscle fibers to function properly. Acidity and energy depletion lead to muscle fatigue—the state in which we feel like we simply can’t go on. If we stop to rest and give our systems a chance to catch up, our muscle pain will slowly fade and our muscle function will be restored.
The Underlying Cause of Chronic Muscle Soreness
Now, back to answering our original question of what causes chronic muscle soreness. In normal movement, muscles contract and release, contract and release, over and over again. When muscles release and get a chance to rest, metabolic wastes are flushed out of our muscles, making the soreness go away and restoring full function. When we hold our muscles in a constant state of contraction, however, this recycling process never gets to happen.
Muscles that are constantly contracted, or being held in a state of tonic contraction, are working very hard even when we’re standing still. So as you can imagine, they require a great deal of energy in the form of ATP. But unfortunately, contracted muscles squeeze the blood vessels in the area, restricting blood flow and reducing the amount of oxygen and glucose that can be carried to the working muscle. This compression of the blood vessels is not problem during a phasic contraction, in which muscles regularly contract and release. But during a tonic contraction, constant compression of the blood vessels leads to ischemia, a condition in which lack of oxygen and nutrients can lead to pain, loss of function, cell damage and even cell death.
Lack of oxygen flow means that cells must use anaerobic metabolism to create energy. In a tonic contraction, this process is constantly happening, even during sleep. Lactic acid is continuously getting produced and being broken down into lactate and hydrogen ions. The constant contraction has the same effect as a strenuous workout; the waste recycling process can’t keep up and hydrogen ions build up in the muscle. The hydrogen ions keep activating pain receptors, causing chronic muscle soreness and pain. So if muscle pain resulting from constant contraction is what you are feeling, then your pain should go away when your muscles release and oxygen flow is restored.
The Cure for Chronic Muscle Soreness
So the cure for chronic muscle soreness sounds easy enough: just release your chronically contracted muscles. But as you probably know from experience, it’s not that easy. Stretching, massage, and even rest often won’t do the trick. Why don’t these approaches work? Because they don’t address the messages that your brain is sending to your muscles to stay tight.
Over the course of our lives, as we repeat certain postures and movements over and over, our nervous system learns to make these postures and movements automatic. For most of us, this learning process often results in keeping certain muscles contracted all the time. The more deeply learned this muscular contraction becomes, the harder it is to release the contraction voluntarily. You can read more about this learning process here.
The most effective and efficient cure for most chronic muscle soreness is a movement technique called pandiculation. Pandiculation contracts and releases muscles in such a way that accurate biofeedback is sent to the brain, naturally resetting the alpha-gamma feedback loop, which controls the level of contraction in muscles.
Pandiculation is one of the techniques used in Clinical Somatic Education, a method of neuromuscular education developed by Thomas Hanna. Pandiculation is very slow, gentle and therapeutic. It can be done hands-on with a certified educator, or on your own at home in the form of self-care exercises. To begin learning Clinical Somatics exercises at home, click here.
Delayed Onset Muscle Soreness (DOMS)
As a side note, there is a difference between the muscle pain felt in an actively contracted muscle and the muscle soreness which occurs after a challenging workout. This second type of muscle soreness is referred to as delayed onset muscle soreness (DOMS), and tends to peak around forty-eight hours after exercise.
Most research suggests that DOMS is a result of structural cell damage that occurs during strenuous exercise, especially types of exercise which involve eccentric contractions such as downhill running. The damaged cells release substances which help to facilitate the healing process, but unfortunately, some of these substances also activate pain receptors. Consider this soreness a reminder from your body to take it easy because you pushed it a little too hard a couple of days ago. As your muscle cells are repaired, the irritating substances are flushed out of your system, and the soreness goes away.
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