Here is a well-written expression of the "party line" that is taken by most medical and physical conditioning experts about delayed onset muscle soreness:
"The good soreness that makes you stronger is called DOMS (Delayed Onset Muscle Soreness) and is caused by microscopic tears in your muscle fibers. It is not caused by lactic acid buildup. When muscles are damaged, they produce healing prostaglandins that cause muscles to become bigger and stronger than before they were exercised vigorously".
Gary Moller comments:
So, DOMS is "good soreness! This is rubbish. DOMS is not good for you.
For a start, the damage to healthy cells which you feel as pain, swelling and stiffness (DOMS), releases massive amounts of cell debris into the body. This debris is toxic to healthy cells, principally because it is rich with oxidants that damage the healthy tissue that is already depleted and exhausted following the workout. Flooding the body with oxidising toxins accelerates the ageing processes. This might be why excessive exercisers do not live as long as those who exercise moderately.
Recovery from exercise that causes DOMS takes from 2-5 days and further vigorous exercise within that period will delay recovery and may even lead to complete breakdown in the form of an injury or infection.
A further problem with doing too much exercise that causes DOMS is the steady loss of flexibility. As any long distance runner will ably demonstrate, the steady loss of flexibility causes the eventual grinding to a halt with passing years. This is because the repair process always has the damaged tiisue shorten and harden a little each time. Again, any runner will tell you that attempts at maintaining flexibility by stretching is painful futility. In fact, most runners give up, other than during token spells such as during injury time!
Take several people off the street and have them walk as fast as they can up the stairwell to the top of the tallest building you can get access to. Have them come down in the lift. Take another group and take them to the top of the building and have them walk quickly to the bottom. Contact them 2 days later and have them rate 0-10 any DOMS.
What you should discover is the group that walked up will report little or no DOMS than the other who will probably report being semi-crippled and this will last several days!
This demonstrates that not all exercise is the same; despite the walking down was far less strenuous, the strenuous walking up was far less damaging to the body. Furthermore, the down walkers, have significant losses of leg flexibility and this loss is lasting.
Exercise that has the muscles actively resisting being lengthened (eccentric contractions) causes DOMS; whereas exercise that has the muscles actively shortening (concentric contractions) only has little or no DOMS. Activities that have high amounts of eccentric include: running, lifting and lowering weights, jumping and lunging. Activities that do not have much eccentric work include: swimming, paddling, cycling, pushing hydraulic exercise machines and walking on the flat.
Try cycling for example: With no preparation, go ride for as long and as hard as you can. The chances are you will have a really sore bum from the seat, a stiff neck and sore hands from a poor bike setup; but your thighs which you thrashed to a standstill will only be mildly sore and tired the following day. By day 2-3 you will be easily able to repeat the workout. Now, I would never suggest that you attempt the equivalent with eccentric-soaked running, would I?
Not all exercise is the same and don't believe everything the experts say. Finally, if you want to slow the ageing process and to be physically active well into old age, I advise you to choose your exercises with care.