Injury prevention The ability of a muscle to stretch determines the range of movement of the various joints of the body. If a muscle between two joints (like the hamstring) is restricted due to lack of flexibility then the joints on either end (your hip joint and knee) cannot move through their full range of motion which in turn affects the joints connected to these joints (the rest of your pelvic structure, lower back, ankles) and so on, creating an inflexible and inefficient movement pattern which over time can lead to poor posture, joint pain, muscle pain and injury. Using equipment such as foam rollers can assist in providing a good stretch to various muscle groups like the ITB, quadriceps or hamstrings.
This is the traditional form of stretching where the position of the joint is maintained without any movement for 20 to 60 seconds at a time. These stretches are generally the most commonly known as there are a large number of standard stretch positions for all major muscle groups of the body.
Makes use of various continuous exercise movements for a certain number of repetitions to increase the range of motion which the muscle can achieve stretching before exercise vs stretching after exercise.
(above images from http://www.nutritioulicious.com/2013/09/dynamic-vs-static-stretches-the-importance-of-both/ and http://fitting.2ndswing.com/stretchingwarming-dynamic-stretches-golf/)
Should I stretch before or after exercise?
Current trends in research and literature reveal conflicting information regarding this debate, however it is generally accepted that performing dynamic stretches before exercise helps improve blood circulation to the muscles as well as helping to become mentally prepared for physical exertion.
The nature of static stretching is slow and controlled and most beneficial when there is increased blood flow and the muscles are warm after exercise, hence the muscle fibres can reach greater lengths without injury and mentally, static stretching becomes a great way to cool down after exercise.