A good mythbusting article on DOMS
Delayed Onset Muscle Soreness. Misunderstood, myth-based explanations abound ...
Many of us have experienced DOMS at some point or other in our lives. DOMS is Delayed Onset Muscle Soreness. It's a mildly painful muscle soreness that comes 24-48 hours after exercise, usually an exercise you haven't done before or haven't done for a long time, and that involves eccentric contractions. Eccentric means lengthening under load. Imagine holding a weight in your hand and lowering it, so your bicep is extending, not contracting, under load. That's an example of an eccentric contraction.
What causes it? Many will say 'lactic acid', and they'll be wrong. There is no such thing as lactic acid in the human body. Ever. It just doesn't happen. I've ranted on about that before, but just to be blunt, from wikipedia :
Contrary to popular belief, this increased concentration of lactate does not directly cause acidosis, nor is it responsible for delayed onset muscle soreness. This is because lactate itself is not capable of releasing a proton, and secondly, the acidic form of lactate, lactic acid, cannot be formed under normal circumstances in human tissues.[citations needed] Analysis of the glycolytic pathway in humans indicates that there are not enough hydrogen ions present in the glycolytic intermediates to produce lactic or any other acid.
Here's the best explanation of what DOMS is and how it's caused that I've ever read. Well worth the 10 minutes of your life it will take to read. Some key points from it :
- Pain killers (NSAIDs etc) don't help. In fact, using many of them in 'normal doses' decreases protein synthesis. Do not use NSAIDs (ibroprufen, naproxen etc) when doing strength training, they reduce the effects of the training AND don't reduce the effects of DOMS.
- The burning sensation when exercising very hard is not related to DOMS
- Muscles will adjust to soreness with time. If you’re unaccustomed to doing a particular exercise or activity, you can bank on being sore the next day or two. But if you keep up the activity, you’ll soon stop getting sore.
- DOMS and actual muscle growth don’t have much to do with each other, no DOMS does not mean no muscle growth, and DOMS does not mean muscle growth. Correlation is not causation!
- DOMS seems to be inflammation of intra-muscular connective tissues
- DOMS itself is not a by-product of muscle fiber inflammation. Being sore does not mean that your muscles are undergoing growth. They might be undergoing repair, but these are not the same things.
- DOMS itself will be caused by any eccentric exercise that you do for
enough total reps. The less accustomed you are to that type of
exercise, the worse the soreness will be after the fact. This can be squats, or a long walk down a hill etc.