Why do our muscles get sore and what can we do to alleviate the soreness?

Muscle Fatigue vs. Muscle Soreness

The pain you feel late in a workout when you are finishing your last set of a weights exercise – or the ache in your legs at the end of a long run – that sensation is muscle fatigue which is different from soreness.Exercise-induced muscle fatigue can occur in response to:

• Short Term Intense Exercise (like sprints)
  
• Sustained Intense Exercise (such as weight lifting sets) or
  
• Prolonged Exercise (such as running long distances)
  

It’s common to feel muscle fatigue at the end of a hard workout and often provides a feeling of accomplishment – you know you had a hard workout. Muscle fatigue also presents itself in the form of pain or discomfort in the hours immediately after exercise.

Muscle fatigue is distinct from the painful soreness from exercise that occurs 24-72 hours after the workout has ended. That soreness is called “Delayed Onset Muscle Soreness” (or “DOMS”) and is a different beast from muscle fatigue. Feeling muscle fatigue during a workout doesn’t necessarily lead to DOMS.

Delayed Onset Muscle Soreness

When we stress our muscles it causes micro-tears in the tissue and the process of rebuilding the damaged tissue is how additional muscle and strength is gained.

The tearing of muscle creates inflammation and more micro-tears create more inflammation. At a certain level of tearing an “inflammatory cascade” occurs and it is this build-up of inflammation that causes DOMS 24-48 hours after a workout. (Note that contrary to popular belief, buildup of lactic acid is not a cause of muscle soreness.) Inflammation primarily causes pain because the swelling pushes against nerve endings.

DOMS can be quite painful and it can take days for the soreness to go away.

DOMS doesn’t occur with every workout. It usually occurs when you perform exercises not usually performed or with big increases in the stress on muscles (such as increasing the amount of weight quickly). Gradually increasing the amount or intensity of exercise (i.e. less than 10%) usually avoids DOMS. Note, however, that soreness is not necessary for muscle growth – micro-tears, repair and increased strength can and does occur without soreness.

Strategies to Treat DOMS

Let’s say you’ve crushed your workout and now a day later you are quite sore. At this point what can you do about it? Science backed remedies to alleviate DOMS include:

• Avoid strenuous exercise with the sore muscles for a few days.
• Engage in light, low-impact exercise. Light workouts increase blood flow to the sore muscles which can help with the inflammation and can speed healing.
  
• Self-massage using a foam roller has been found to reduce the effects of DOMS as the deep tissue stimulation increases blood flow to the sore muscle areas.
• Similarly, a deep-tissue massage has been found to be effective in treating DOMS soreness (there is still some controversy whether massage helps – studies vary).
• Some studies have found drinking coffee/caffiene before a workout reduces the severity of DOMS and eating tart cherries or drinking a tart cherry drink after a tough workout reduces DOMS.
• Staying hydrated before, during and after workouts has been found to reduce DOMS.
• Some studies have found consumption of omega-3 fatty acids for the days following workouts can help reduce the effects of DOMS.

There are a lot of other strategies that are unproven or have been dis-proven with respect to treating DOMS. These include:

• Studies on stretching have not found that it helps alleviate DOMS
• Ibuprophen and other pain relievers can provide temporary pain relief but don’t speed healing.
  
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• Use of heat and hot baths have not been found to reduce DOMS.
• Consumption of protein supplements before, during or after a workout has not been found to help alleviate DOMS. That being said, consuming carbohydrates after a workout and ingesting adequate protein is important for muscle repair and growth.