Stretching should be done to relieve tension and stress during or after a workout. Stretching should also be done to increase your range of motion and flexibility. Flexibility is the ability to move your joints throughout their full range of motion. Flexibility can also be referred to as the interrelationship between muscle and joint mobility. During a workout you should only stretch to the point of short discomfort. After a workout, or during a normal stretch period you should stretch to the point of moderate discomfort. This stretch period is targeted towards increasing your range of motion and the prevention of shortened muscles. When you are sore a day after a workout it is also good to perform moderate intensity stretching to reduce post-exercise muscle soreness.
Your level of flexibility is genetically predetermined in relation to your age and gender. Younger people are typically more flexible than older people. Women are often more flexible than men. Exercises that are performed in a restricted range of motion continuously help you develop shorter muscles. Shorter muscles can decrease range of motion and increase the risk of injury. The proper way to exercise is to fully extend and contract your muscles keeping them long and flexible. This will also promote more muscle definition. Prolonged sitting and a sedentary lifestyle can put alot of pressure on the lower back, decrease your conditioning level and also decrease your flexiblity.
You should stretch for 10 to 15 minutes after a workout, no more than 20 minutes. Hold a stretch for 15 to 20 seconds maximum.
Static Passive Stretching:
Involves a partner (or a personal trainer) applying force to move you towards your full or maximum range of motion. It is important to breath normal deep breaths and relax during this stretch period. This type of stretching is prohibited before weight training because it can cause weakness in muscles.