It's caused by working the muscle to fatigue and the muscle is trying to recover and the muscle knows that it has to grow to handle what your doing to it so if you keep lifting heavy you will be sore as the muscle keeps growing to handle the extra weight your constantly putting on it.
True.
Delayed onset muscle soreness
This article says that it isn't related to lactate acid buildup and suggests it might be caused by muscle tissue breakdown: http://www.sport-fitness-advisor.com/delayed-onset-muscle-soreness.html
delayed onset muscle soreness doctor of medicine
The leading hypothesis for delayed onset muscle soreness are the: connective tissue damage hypothesis the skeletal muscle damage hypothesis the spasm hypothesis
Delayed onset muscle soreness, DOMS, occurs following overexertion.. Pain during muscle use can be caused by a spasm, which slows arterial blood flow to the area and is referred to as claudication.
DOMS stands for delayed onset muscle soreness, it is caused from working out muscles and them developing small tears causing the muscle to grow. The only way to treat it is to let it pass the soreness will go away when the muscle heal.
Iain Douglas Hill has written: 'Delayed onset muscle soreness (DOMS)'
Usually it will go away in less than 24 hours.
There are several substances and mechanisms that cause muscle pain. The most common are immediate onset and delayed onset pain. Immediate onset pain is caused by muscle fatigue which comes from exercise of physical activity and occurs when the muscle has rerached its conditioned fatigue point. Delayed onset pain occurs 24-48 hours after the muscles have been worked to their fatigue point and are rebuilding themselves. This is the muscle soreness that many people experience when they start a new exercise program.
Lactic Acid forms in the muscles as a metabolic by-product of intense muscle use. The resultant lactic acid (CO2 Buildup) in the muscle causes a delayed onset muscle stiffness/soreness.
The best way to relieve the soreness, called delayed-onset pain, that comes one to two days after physical exertion is by techniques that affect the muscle fibers and circulation; petrissage is one of the best, usually.