The risk of overuse injuries rises when weekly mileage exceeds 40 to 50 miles. Stop running if joint pain or swelling exists. Faulty techniques and abnormal bone structure can affect running performance and risk for injury. Examples are an abnormally curved spine, differences in leg length, high arches, and excessive muscle tightness. Abnormal shoe wear patterns are a sign of these problems and the right shoes can correct them.
Proper shoes can also reduce the risk for overuse injuries of the knees and ankles.
Terrain, altitude, temperature, and air quality can affect performance and physical health. Run on soft surfaces like a track, dirt road, grass, or treadmill. Avoid running down hills. Downhill running puts extra stress on the knee and lower leg. Avoid running in hot or cold temperature extremes and when pollution levels are high.