The Science of Stiffness

Anyone who has done any form of strenuous activity will have felt that painful ache in the muscles for a few days after exercise. A lot of you may have decided that this pain couldn’t possibly be good for you and, therefore, have avoided any exercise since. Some of you might have decided you quite like that achy feeling, reminding you of what a good workout you had the day before. Basically, this mild discomfort is not bad for you and the good news is it won’t last forever.

Various myths regarding muscle soreness as a result of exercise exist. The most common is the idea that a build up of lactic acid in the muscle causes muscle soreness the next day. It is true that there is a build up of lactic acid in the muscle tissue with strenuous exercise; however, this lactic acid is removed within an hour of finishing exercise. Thus, it is not the cause for pain and stiffness that materializes the following day.

Muscle stiffness or pain after exercise is termed delayed onset muscle soreness (DOMS). There are two key models to explain this exercise effect. The first is known as the Local Ischemic Model. This model suggests that following either strenuous exercise, or even moderate, non-traumatic exercise, there is swelling in the soft tissue. This causes an increase in tissue pressure and a local reduction in blood and oxygen supply to the muscle (ischemia). This in turn causes muscle spasm and the pain known as DOMS.

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The second model is known as the Mechanical Trauma Model. Here, it is suggested that there is structural damage (microtears) to the muscle tissue as a result of increased mechanical forces during muscle contraction. This again leads to swelling and inflammation in the muscle tissue, resulting in pain.

Neither of these models suggests that there is permanent damage to the muscle tissue. In fact, it is recommended that one repeats the same exercise on a regular basis so that the muscle tissue can adapt to the increased force placed on it. This is called the “repeated-bout effect”. The more the exercise is performed, the quicker the muscle tissue adapts, reducing muscle soreness.

So, next time you wake up the morning after exercise, cursing your trainer, the gym, exercise and life in general because you can’t walk up stairs or stand up from the toilet, think of the positive changes taking place to the muscle. Take yourself off to the gym and do a light exercise session with a good cardiovascular warm-up and lots of stretching – even if it hurts a little. This will increase blood flow to the sore muscle tissue, improve flexibility and thus reduce pain and stiffness.