Stretching is a common activity used by athletes, older adults, rehabilitation patients, and anyone participating in a fitness program.
While the benefits of stretching are known, controversy remains 2 bbws 1 athletic guy the best type of stretching for a particular goal or outcome. The purpose of this clinical commentary is to discuss the current concepts of muscle stretching interventions and summarize the evidence related to stretching as used in both exercise and rehabilitation. Human movement is dependent on the amount of range of motion ROM available in synovial joints. In general, ROM may be limited by 2 anatomical entities: Joint restraints include joint geometry and congruency as well as the capsuloligamentous structures that surround the joint.
Muscle provides both passive and active tension: Structurally, muscle has viscoelastic properties that provide passive tension. Active tension results from the neuroreflexive properties of muscle, 2 bbws 1 athletic guy peripheral motor neuron innervation alpha motor neuron and reflexive activation gamma motor neuron. Obviously, there are 2 bbws 1 athletic guy factors and reasons for reduced joint ROM only one of which is muscular tightness. Passively, muscles can become shortened through postural adaptation or scarring; actively, muscles can become shorter due to spasm or contraction.
Regardless of the cause, tightness limits range of motion and may create a muscle imbalance. Clinicians must choose the appropriate intervention or technique to improve muscle tension based on the cause of the tightness.
Stretching generally focuses on increasing the length of a musculotendinous unit, in essence increasing the distance between a muscle's origin and insertion. In terms of stretching, muscle tension is usually inversely related to length: Inevitably, stretching of muscle applies tension to other structures such as the joint capsule and fascia, which are made up of different tissue than muscle with different biomechanical properties.
Three muscle stretching techniques are frequently described in the literature: Static, Dynamic, and Pre-Contraction stretches Figure 2. The traditional and most common type is static stretching, where a specific position is held with the muscle on tension to a point of a stretching sensation and repeated.
This can be performed passively by a partner, or actively by the subject Figure 3. Techniques of Muscle Stretching.
Static stretching of the posterior shoulder Used with permission of the Hygenic Corporation. There are 2 types of dynamic stretching: Active stretching generally involves moving a limb through its full range of motion to the end ranges and repeating several times. Pre-contraction stretching involves a contraction of the muscle being stretched or its antagonist before stretching. The most common type of pre-contraction stretching is proprioceptive neuromuscular facilitation PNF stretching.
Resistance can be provided by a partner or with an elastic band or strap Figure 4.
Contract-Relax stretching with stretching strap Used with permission of the Hygenic Corporation. Post-facilitation stretch PFS is a technique developed by Dr. Vladimir Janda that involves a maximal contraction of the muscle at mid-range Figure 5 with a rapid movement to maximal length followed by a second static stretch. Many studies have evaluated various effects of different types and durations of stretching. Outcomes of these studies can be categorized as either acute or training effects.
Acute effects measure the immediate results of stretching, while training effects are the results of stretching over a period of time. Stretching studies also vary by the different muscles or muscle 2 bbws 1 athletic guy that are being examined and the variety of populations studied, thereby making interpretation and recommendations somewhat difficult and relative.
Each of these factors must therefore be considered when making conclusions based on research studies. Several systematic reviews of stretching are available to provide general recommendations. The effectiveness of stretching is usually reported as an increase in joint ROM usually passive ROM ; for example, knee or hip ROM is used to determine changes in hamstring length.
2 bbws 1 athletic guy Static stretching often results in increases in joint ROM. Interestingly, the increase in ROM may not be caused by increased length decreased tension of the muscle; rather, the subject may simply have an increased tolerance to stretching. Increased tolerance to stretch is quantified by measuring the joint range of motion with a non-standardized load.
This is an important question to consider when interpreting the results of studies: Static stretching is effective at increasing ROM.
The greatest change in ROM with a static stretch occurs between 15 and 30 seconds; 1314 most authors suggest that 10 to 30 seconds is sufficient for increasing flexibility. Unfortunately, however, static stretching as part of a warm-up immediately prior to exercise has been shown detrimental to dynamometer-measured muscle strength 19 — 29 and performance in running and jumping.
Contraction of a muscle performed immediately before it is stretched is effective at increasing ROM.
Interestingly, ROM increases are seen bilaterally with pre-contraction stretching, 43 supporting a possible neurologic phenomenon. The specific phenomenon associated with an increase in flexibility following a pre-stretch contraction remains unclear. Interestingly, electromyographic EMG studies have shown that muscle activation remains the same 744 or increases after contraction.
Some researchers suggest that Hoffman reflexes H-reflexes are depressed with a pre-contraction stretch. It is possible that the lowered excitability levels may allow muscle to relax through the gamma motor neuron system despite an increased activation through the alpha system.
Obviously, more research is needed to investigate these neurological effects of pre-contraction stretching.