I had an interesting conversation with several students today on the topic of stretching. These students were surprised when I shared with them what the research on stretching has found.
1) Stretching prior to or immediately after physical activity has not been found to reduce the likelihood of injury.
2) Stretching immediately prior to physical activity has not been found to improve performance. In fact the opposite has been found: stretching immediately prior to physical activity impairs performance.
3) Stretching can be effective to increase range of motion, but the stretching needs to cause micro damage to the muscle, tendons, ligaments. During the subsequent healing process the length of muscle, tendon, and ligament increases. The "key" word is "micro" damage. Stretching the muscle, ligament, and tendons too much may cause "macro" damage (i.e., strains and tears).
Based on these research findings . . .
1) you should regularly stretch between performances of physical activity to increase range of motion
2) you don't need to stretch before or after physical activity; instead you should perform low intensity movements as warm-ups before and cool-downs after physical activity.