5. Sprains and Strains

• A sprain is a stretch and/or tear of a ligament, the fibrous band of connective tissue that joins the end of one bone with another. Ligaments stabilize and support the body's joints. For example, ligaments in the knee connect the upper leg with the lower leg, enabling people to walk and run.

• While the intensity varies, pain, bruising, and inflammation are common to all three categories of sprains -- mild, moderate, severe. The individual will usually feel a tear or pop in the joint. A severe sprain produces excruciating pain at the moment of injury, as ligaments tear completely, or separate from the bone. This loosening makes the joint nonfunctional. A moderate sprain partially tears the ligament, producing joint instability, and some swelling. A ligament is stretched in a mild sprain, but there is no joint loosening.

• A strain is a twist, pull and/or tear of a muscle and/or tendon. Tendons are fibrous cords of tissue that attach muscles to bone.

• Typical indications of a strain include pain, muscle spasm, muscle weakness, swelling, inflammation, and cramping. In severe strains, the muscle and/or tendon is partially or completely ruptured, often incapacitating the individual. Some muscle function will be lost with a moderate strain, where the muscle/tendon is overstretched and slightly torn. With a mild strain, the muscle/tendon is stretched or pulled, lightly.

• Back strain. When the muscles that support the spine are twisted, pulled or torn, the result is a back strain. Athletes who engage in excessive jumping are vulnerable to this injury.

• Hamstring muscle strain. A hamstring muscle strain is a tear or stretch of a major muscle in the back of the thigh. The injury can sideline a person for up to six months. The likely cause is muscle strength imbalance between the hamstrings and the muscles in the front of the thigh, the quadriceps. Hamstring injuries tend to recur.

6. Stress Fractures

• A stress fracture is an overuse injury. It occurs when muscles become fatigued and are unable to absorb added shock. Eventually, the fatigued muscle transfers the overload of stress to the bone causing a tiny crack called a stress fracture.