The amount of training you carry out plays a key role in determining your real injury risk. Studies have shown that your best direct injury predictor may be the amount of training you completed last month. Fatigued muscles do a poor job of protecting their associated connective tissues, increasing the risk of damage to bone, cartilage, tendons and ligaments. If you are a runner, the link between training quantity and injury means that the total mileage is an excellent indicator of your injury risk. The more miles you accrue per week, the higher the chances of injury. One recent investigation found a marked upswing in injury risk above 40 miles of running per week.
If you have been injured before then you are much more likely to get hurt than an athlete who has been injury free. Regular exercises have a way of uncovering the weak areas of the body. If you have knees that are put under heavy stress, because of your unique biomechanics during exercises, your knees are likely to hurt when you engage in your sport for a prolonged time. After recovery, you re-establish your desired training load without modification to your biomechanics then your knees are likely to be injured again.
The second predictor of injury is probably the number of consecutive days of training you carry out each week. Scientific studies strongly suggest that reducing the number of consecutive days of training can lower the risk of injury. Recovery time reduces injury rates by giving muscles and connective tissues an opportunity to restore and repair themselves between work-outs.
Some studies have shown that athletes who are aggressive, tense, and compulsive have a higher risk of injury than their relaxed peers do. Tension may make muscles and tendons tighter, increasing the risk that they will be harmed during workouts.
Many injuries are caused by weak muscles which simply are not ready to handle the specific demands of your sport. This is why people who start a running program for the first time often do well for a few weeks but then as they add the mileage on, suddenly develop foot or ankle problems, hamstring soreness or perhaps lower back pain. Their bodies simply are not strong enough to cope with the demands of the increased training load. For this reason, it is always wise to couple resistance training with regular training. Weak or inhibited gluteal muscles can be the cause of lower back and lower limb injuries.
Muscle stiffness refers to the ratio between the change in muscle resistance and the change in muscle length. Muscle stiffness is directly related to muscle injury risk and so it is important to reduce muscle stiffness as part of a warm up.
Research work by McNair (2000) and Knudson (2001) has indicated that only dynamic stretches - slow controlled movements through the full range of motion - decrease muscle stiffness. Static exercises did not decrease muscle stiffness.
This suggests that dynamic stretches are the most appropriate exercises for warming up and not static stretching exercises. Static stretches are perhaps more appropriate for the cool down as they help to relax the muscles and increase their range of movement.