The objectives of stretching are to:
- Provide a greater range of movement (flexibility) in order to facilitate more efficient functional movement.
- Increase performance in sporting endeavor.
- Prevent injury in day-to-day living and in sports activity.
Several different types of stretching are available and some are more widely used than others. The following describes the main types of stretches.
Static stretching requires you to hold a muscle or muscle group in an elongated position for a time of 10 seconds to one minute, usually at a position of strain or slight discomfort. Older adults may benefit from 30-60 second stretches. Static stretching includes exercises like the quadriceps stretch shown in the diagram.
Dynamic stretching involves movement of a muscle or muscle group in such a way that the muscle is elongated with a body movement and the action is repeated. Dynamic stretching includes leg swings, arm and torso swings, and walking lunges. In dynamic stretching, the point of maximum stretch is not held but forms part of a specific movement, usually as a slower movement than in ballistic stretching (below).
Although ballistic stretching is similar to dynamic stretching in that movement is involved, ballistic stretching utilizes fast 'bouncing action' and this has been associated with injury in the past. Examples are toe touches and side bounces. Even so, ballistic stretching should not be ruled out completely. To avoid injury, you should warm up with light aerobic exercise before ballistic stretching. Use ballistic stretching for best results in sports involving ballistic movements, such as basketball, volleyball and soccer.
Proprioceptive Neuromuscular Facilitation (PNF)
PNF stretching is usually regarded as a more advanced form of flexibility training involving both the stretching and isometric contraction of the muscle. You require a partner for PNF stretching. A tensed (isometric) muscle is held for the set time, then the partner facilitates a further 'stretch' in a passive, static form.
Which Stretches Work Best
Static and ballistic stretching, properly performed, elicit similar gains in range of motion, while dynamic stretching is more useful for warmups before competition. PNF stretching may produce the best gains, but the practicality is limited because of the requirement for a partner.
Time and Frequency of Stretching and Repetitions
The American College of Sports Medicine in their review, say that holding a stretch for 10-30 seconds at the point of tightness or slight discomfort enhances joint range of motion. For most people, additional benefit does not accrue from longer duration. However, for older trainers, additional benefits may result from stretches from 30-60 seconds.
Repeating each flexibility exercise 2-4 times is effective. Results are seen from 3-12 weeks. The general goal is to reach 60 seconds of stretch time per muscle or muscle group. This can be composed of 1x60, 2x30, or 4x15, for example. Performing stretching 2-3 times per week is effective, but greater gains in range of motion can be achieved with daily flexibility exercise.
Which Muscle Groups?
You should stretch the major muscle-tendon groups of the shoulder, chest, neck, trunk, lower back, hips, front and back of legs, and ankles. A routine should take no longer than 15 minutes.
Preparing for Stretching
Flexibility exercise is most effective and safe when the exercise is performed when the muscles are warm. Warm up with light aerobic activity -- jogging on the spot for example -- or use heat packs or take a warm bath or shower.
For dynamic power sports like track sprinting, football and basketball, static stretching and lengthening of the muscles has been shown to inhibit performance when done prior to competition during warmup. Utilize dynamic stretching in warmups prior to competition for these and similar sports.
Even so, for recreational sports and general fitness activities, the ACSM recommend you do flexibility exercise after cardiorespiratory or resistance exercise -- or alternatively, as a stand-alone program.