Stretching is a common activity used by athletes, seniors, rehabilitative patients and anyone involved in a fitness program. While the benefits of stretching are known, there is still a debate about the best type of stretch for a particular target or outcome. The objective of this clinical review is to discuss the existing concepts of muscle stretching intervention and to summarize evidence of the stretching associated with exercise and rehabilitation.
Human motion depends on the range of motion (ROM) available for synovial joint. In general, ROM may be limited to two anatomical entities: joints and muscles. Joint limitations include joint geometry and consistency and capsule structures around the joints. The muscle provides passive and active tension: the passive muscle tone depends on the structural characteristics of the muscles and the surrounding fascia, while the dynamic muscle contractions provide the active tension (figure 1). In the structure, the muscle is viscoelastic, thus providing passive tension. Active tension is caused by the neuronal reflex of muscles, especially peripheral motor neuron (alpha motor neuron) and reflex activation (gamma motor neurons).
Obviously, there are many reasons for reducing joint roms, and only one of them is muscle tension. Tension increased by active or passive mechanisms is the result of muscle tension. Passively, muscles can be shortened by postural adaptation or scarring; Actively, muscles may shorten due to spasms or contractions. Whatever the cause, loosening limits the range of motion and can cause muscle imbalances.
Clinicians must choose appropriate interventions or techniques to improve tension caused by tension. Stretching generally focuses on increasing the length of a muscle tendon unit, essentially increasing the distance between the muscle’s origin and insertion. In terms of stretching, muscle tone is usually inversely proportional to length: muscle tension is associated with increased muscle length, while increased muscle tone is associated with decreased muscle length. Inevitably, muscle tension exerts tension on other structures, such as joint sacs and fascia, which are composed of different tissues, and different muscles have different biomechanical properties.
Three types of muscle stretching techniques are often described in the literature: static, dynamic and preshrunk stretching (figure 2). The traditional and most common type is static stretching, where a specific position is repeated with the muscle strain to a stretch of sensory point. This can be done either passively by the partner or by the main body (figure 3).
There are two types of dynamic stretching: active and ballistic stretching. Active stretching usually involves moving the limb through its entire range of motion to the end and repeated multiple times. Ballistic-stretching involves quick alternating motion or “bounce” in the final range of motion, but no longer recommended for ballistic stretching due to increased risk of injury. 1
The preshrunk stretch involves the contraction of the muscle or antagonist that is stretched before stretching. The most common type of preshrunk stretch is the ontology-sensory neuromuscular promotion (PNF) stretching. There are several different types of PNF stretching (table 1), including “contract relaxation” (CR), “relaxation” (HR) and “contract relaxation agent contract” (CRAC). This is usually done by allowing patients or patients to shrink and contract muscles for up to 10 seconds between 75 and 100 per cent during the technical process. Resistance can be provided by partners or provided by elastic bands or bands (figure 4).