Varieties of Stretching
Many medical and allied health professionals are concerned with the assessment and promotion of flexibility, including osteopathy, chiropractic and physiotherapy. Asanas, specialised techniques which include stretching, have been performed for thousands of years in yoga and other eastern belief systems. Taekwondo, judo and karate all work on advanced flexibility to enable the performance of their martial techniques. There is no precise definition of flexibility but the anatomical ability of the body's joints to pass through their ranges of motion is often quoted.
Static versus Ballistic Stretching
Many aspects of stretching are controversial and one aspect is the discussion about the relative merits of ballistic and static stretching. There may be some benefit in performing ballistic stretches in terms of maintaining interest as static regimes can be a bit....static, ballistic stretching can be rhythmical and add dynamism to a performance. Most sporting and hobby activities are dynamic in nature and ballistic training permits the practice of manoeuvres specific to the activity. Static stretches may not relate very closely to the active nature of some sports.
There are however several potential disadvantages with ballistic stretching. When a muscle and its connective tissue structures are stretched rapidly they are unable to adapt due to the speed and force and the tendency for the muscles to contract reflexly. For effective tissue lengthening the contractile units should all be relaxed. Using lower forces for longer times has been shown to be more effective at lengthening tissues. Momentum can develop if stretches are done ballistically, potentially leading to the tissues being overstretched and exceeding their stress tolerances.
Static stretching occurs when a stretch position is held for a defined period of time at least once, but it could be more times. The stretch should be performed in a controlled manner, without any movement or speed of movement. Static stretching has been researched and shown to be effective in changing the ranges of movement of joints. Static stretches are easier and more convenient to perform, require less energy and may result in less muscle soreness, but many of these things have not been proven.
Joint ranges of motion are altered by stretching but there are usually some ballistic parts of most activities and sports. The benefits of stretching have been variously reported as:
Warm up is enhanced by stretching. As stretching does not increase the temperature of contractile structures this seems not to be the case.
Cooling down is promoted by stretching. Cooling down involves blood leaving the contracting muscles and returning to the core circulation of the body, something which cannot be promoted by stretching passively.
Delayed onset muscle soreness (DOMS) is relieved by stretching. This idea has not been supported by any evidence.
Performance in athletics and sport is improved by stretching. Dynamic flexibility is more closely allied to athletic ability and static stretching has little evidence to support this idea.
Prevention of injury is enhanced by stretching. Injury may be more likely with lack of flexibility but stretching to increase this has not been shown to limit injury. The likelihood of injury may even be increased by static stretching before exercising.
In physiotherapy movements of the patient are classified in slightly different ways and this can also be applied to stretching. If a person moves their joint through a range of movement the movement is said to be active, in other words performed by the person themselves. If the physiotherapist moves a person's limb for them entirely the movement is said to be passive, performed by somebody else. Stretching can be looked upon in the same way.
A patient can actively stretch their joint by lifting their arm up with their own power, stretching the opposite set of muscles and structures. The normal joint movement is termed physiological and if there is a restriction in the joint the physiotherapist will want to know if this is due to weakness, stiffness or pain to decide the treatment. The passive physiological range will give important clues as to which of these problems is the culprit. If the physiotherapist finds that passive stretches allow the full joint movement without pain then they will deduce that joint weakness is the problem to be treated. Accessory movements are also used by physiotherapists, encouraging the gliding and sliding movements which happen during normal actions.