General Muscle Soreness
General muscle soreness is usually caused by a sudden increase in exercise or activity that the body is not used to (for example, the first day of spring gardening). This can cause the muscles to become tight or go into spasm, which causes pain and possibly reduced power in the affected muscle.
Muscle spasms can also be aggravated by stimulants such as caffeine), some medications, and emotional stress.
Although rest usually helps to reduce general muscle soreness and pain from tightness or spasm, without additional soft tissue treatment the simple activities of daily life can cause it to reappear.