Anyone who exercises regularly is at some point likely to get a modest injury. It just comes with the territory. The best way to reduce that likelihood is to warm up properly and stretch before and after you exercise.
Generally there are three modest and common problems, excluding those that may require medical intervention – muscle soreness, strains and sprains. The most common is muscle soreness that occurs 24-48 hours after exercise as muscle tissue that has been stressed by exercise begins to heal, or lactic acid is released into the muscle. It can be mild to severe (I can hardly walk!), is natural and should dissipate gradually on its own.
Beyond that, overstressed tissues can evolve into actual injuries like strains or sprains, which involve connective tissues like muscles, tendons or ligaments and need more attention. Strains can result when muscles or tendons are overstressed, usually around the lower back, shoulder, elbow, knee or ankle. The pain is usually localised to a very specific area, unlike muscle soreness. The best thing to do is try to limit use of that area and ice it for 15-20 minutes as soon as possible. If soreness continues beyond a day or two try switching to moist heat like a hot wet towel.
A sprain occurs when a ligament (which connects bone to bone) is injured. The symptoms are very similar to a strain, except there is often some swelling. Treat as you would for a strain, except that if the swelling persists it is recommended to compress the area with a bandage and elevate it. Sprains can get worse, so be more careful with these. They are more common in the shoulder – mainly because there is limited space in the shoulder joint and tissues can get pinched – and elbow. When they occur in the lower back, the conventional wisdom is to get in bed and rest. However, that can be counterproductive and cause muscle spasm. It’s often better to maintain fairly regular activity, just try not to stress the lower back. If symptoms consult your doctor. It’s all worth every ache!