Critical Analysis of Stretching Theory

George Hynec

Stretching is an activity that involves placing a part of one’s body into a position that will lengthen the muscles and tendons. The result of increasing the length of the muscles and tendons is a reduction in muscle tension which in turn makes it possible for the range of movement to be increased. Muscles need to be flexible to achieve peak performance and stretching is the most effective way developing flexible muscles and tendons.

Flexibility is the ability to maintain an extended position at one end of the joint’s range of motion (ROM) with the intention to increase and strengthen the range of motion. Poor flexibility results in tight, stiff muscles that limit our range of motion. Tight muscles may also cause loss of strength and power during sports or physical activity. Flexibility training may or may not include stretching exercises but includes exercises that alter the nervous system control of the muscles to allow greater range of motion to take place in the joints

lunge psoas stretch

– Bill Hartman.

According to Pavel Tsatsouline (author of ‘Super Joints’ and ‘Relax into Stretch’) there are two types of flexibility, passive and active. Passive flexibility is the muscles’ ability to stretch with the help of an external force, while active flexibility is the muscles ability to assume a stretched position using one’s own strength. Active/dynamic flexibility has the ability to also improve one’s passive flexibility by facilitating relaxation of the antagonists. I.e. when the agonist contracts, its antagonist relaxes. This in turn promotes flexibility, both passive and active, by helping to relax the resisting muscle. The greater the difference between one’s active and passive flexibility (active flexibility deficit) the greater the risk of injuries (Supertraining by Dr Siff and Dr Verkhoshansky).

Just as there are different types of flexibility there are different types of stretching – dynamic, static/active, static/passive, isometric, PNF (most common methods being CR and CR/AC).

The traditional approach to flexibility has failed as abysmally as the low fat diets have failed in making us less fat. The reason being is the assumption that muscles and connective tissue need to be stretched and the most popular type of stretching employed has been static/passive (relaxed) stretching, most frequently practiced as part of a warm up, and widely used in both athletic and general fitness environments. Visit any martial arts schools and you will invariable see strenuous static stretches done prior to training. This is a problem – performing dynamic movement, like in martial arts, immediately after static stretching is likely to lead to injuries. Static stretching increases tolerance to pain. According to Ian Shrier MD, PhD “It does not seem prudent to increase one’s tolerance to pain, possibly create some damage at the cytoskeletal level, and then exercise this damage anaesthetized muscle”.

As for the claim that static stretching in a warm-up prevents injuries – there is no scientific evidence of that.” In fact some studies indicate the opposite (see reference further below to David Lally’s study). Cold muscles have poor blood supply, lack elasticity and therefore are more prone to injury.

Static stretching (relaxed passive) does increase flexibility but is not very effective in strengthening the muscle particularly at the end of range of motion. Muscle which is w

eak in the stretched position can easily be injured during exercise or sport activity. The static stretching also lacks the capacity to immediately reduce tension in very tight muscles. The key is to make your muscles stronger in the stretched position. I.e. you can improve your flexibility provided you increase the strength of your muscles. PNF type of stretching due to its use of static contraction increases strength. So, not only is the athlete becoming more flexible, he/she becomes stronger particularly in the extreme range of motion.

So, does stretching improve flexibility? Well it depends on how you stretch and when you stretch. Why is it that almost everyone is able to raise one leg and rest it on a chair or table at 90 degree angle, yet would not be able to do a full split? The answer is – fear and tension, sometimes referred to as ‘stretch reflex’. When a muscle is stretched past a certain point, stretch receptors send signals to the surrounding muscle fibers which cause them to contract – making further stretch of the muscle no longer possible. One’s nervous system has (over the years) picked up the preferred muscle length and keeps it that way.

According to Tsatsouline “it is not short muscles and connective tissues that make you tight, it is your nervous system”. When you master the muscle tension you will be as flexible as you want to be. In short, if you use proper technique such as joint mobility, dynamic stretches prior to a workout and PNF (CR and CA) type of stretching after a workout stretching does indeed lead to greater flexibility and stronger muscles. Fear, anxiety and pain on the other hand reduce flexibility. As mentioned earlier, stretching statically prior to training can lead to injuries. In a study carried out on 1500 runners who took part in the Honolulu Marathon, exercise physiologist David Lally, Ph.D linked stretching before exercise with a higher risk of injury (Running Research News, vol.10(3), pp.5-6, 1994). However, athletes who stretched after their workout experienced lower rate of injuries.

The other point worth making regarding flexibility is joint mobility. It is quite rare to come across a stretching program that incorporates joint mobility exercises. If one embarks on a stretching program without paying attention to the joints one is asking for trouble. It is much safer to commence stretching program only after improving joint mobility. If the joint is not comfortable outside of a particular range of motion the ‘stretch receptors’ will make sure the muscles protect the joint by restricting the movement. Forcing muscles to become more flexible via stretching when the joints are not ready for the increase range of motion can lead to injury or reduced stability. A flexible joint has the ability to move through a greater range of motion and needs less energy to do so. To move a joint through its full range of motion you need to use your muscles. This increases the blood flow to the muscle, making it more pliable and therefore less prone to injury. The nerves attached to the muscle become energized, priming your muscles and joints for action. Also, one has to

bear in mind that joint structures can vary between individuals and this needs to be recognized when assessing flexibility.

In general fitness, flexibility is not as important as in professional sports. Unless you are into gymnastics, martial arts or other sports requiring extreme flexibility there is no need to go overboard on flexibility. Excessive flexibility can be just as dangerous as not being flexible enough, as both will increase the risk of injury.

Performing weight bearing exercises in full range of motion itself will result in a reasonable degree of flexibility. Some experts believe that resistance training tightens muscles making them more prone to injury. I don’t really believe that to be the case, provided you are lifting weights properly. After all, Olympic weightlifters are among the most flexible athletes while they spend little time on stretching.

In most sports flexibility, particularly active one, is key to good performance, so working on one’s active flexibility and increasing strength in stretched out position in t

he agonists is essential. In gymnastics for example maximal development of flexibility is necessary in order to perform the basic technique. Good flexibility makes it possible for an athlete to execute movements more economically.

Stretching should be specific to the sport and the individual athlete. For example, a wrestler would be putting more emphasis on isometric static type of stretching com

pared to, say a kickboxer, who would be spending more time on dynamic flexibility, particularly flexibility of the hips. Dynamic stretches will develop active ROM and have the advantage of being performed at sport specific speeds. According to Logan and McKinney (1970) the principle of specific adaptation to imposed demands, in case of flexibility, means that eventually one should stretch at speed not less then 75% of the maximal speed used in the actual movement, for example a kick.

Iashvili (1983) found that active ROM and not passive ROM had a closer relationship to sports performance. Active ROM is defined as the ROM athletes can produce the

mselves, whereas passive ROM is produced with assistance or by gravity. Since athletes must be able to generate the movement themselves then developing active ROM is far more important then passive ROM. For example, martial artist in kicking disciplines such as Tae Kwon Do needs to be able to lift his/hers own leg using the hip flexor muscles.

Too much flexibility for a runner, on the other hand, may not be desirable. The ankle, knee and hip joints stay within the mid-range of motion during endurance running, so maximum static ROM will not have much effect. It has also been shown that stiffer leg muscles in endurance athletes may make them more economical in terms of oxygen consumption at sub max speeds (De Vries). Sprinting, martial arts, gymnastics involve movements of much larger ROM therefore depend on good flexibility. However, as already pointed out, d

evelopment of flexibility must be specific to the sport. If a soccer player developed same type of flexibility as a gymnast, he would be of a greater risk of injury as extremely mobile joints may become unstable. It is important for an athlete to give all major muscles equal attention. For example, a very common occurrence among runners is dominant quads but weak hamstring. If one of the opposing muscles is stronger or more flexible than the other than this is likely to lead to imbalance and may subsequently result in injury due to additional pressure being put on the weaker muscle.

Joint mobility and dynamic stretches are a good warm-up exercise as they improve dynamic flexibility which is vital in sports such as martial arts, gymnastics, athletics.

At the end of exercise, when static and CR/CA type of stretching is applied it improves muscle recovery, relieves muscle tension and improves blood flow in the muscle. Stretching can also be used as part of a cool down routine. Proper stretching program which leads to improved maximum ROM results in more elastic muscles. This suggests that stretching is not only for flexibility but it will also increase strength and increased strength leads to better athletic performance. Stretching improves muscular balance and posture. It promotes muscular relaxation therefore allowing muscles to function more efficiently unlike a tense muscle which requires more energy to execute a particular movement.

Another benefit of stretching is that it helps bring fresh blood supply to the muscle therefore increasing the oxygen content of the muscle cells. The increased blood supply helps

flush out lactic acid. Stretching after exercise stimulates the transportation of amino acids into the muscle cells, accelerates protein synthesis inside the cell and inhibits protein degradation.

Some studies also suggest that stretching improves neuromuscular co-ordination. Specifically, nerve impulse velocity increases which helps opposing muscle groups to work in a more co-ordinated fashion.

In conclusion, stretching is necessary for anyone involved in sports or physical activity and should be designed accordingly. Stretching program should be individualised based on person’s level of conditioning and physical make-up. What is important is the type of stretching performed and when it is performed. Why so many people still use only static stretches to develop flexibility, and often as part of a warm up routine, is hard to understand.

From personal experience I find that performing joint mobility drills and dynamic stretches (in addition to a warm-up) prior to exercise or sporting activity, and stretching statically with or without isometric tension, after exercise, helps recovery by relieving muscle spasms and improving blood flow to the muscles as well as increasing strength.

Improved flexibility helps reduce aches and pains, lower risk of injury and is a great way to relax. To achieve good levels of flexibility it is recommended to combine dynamic and isometric stretches with strength exercises such as weight lifting, or practice ‘resistance stretching’ where strength is improved while in a stretched position.

Lastly, once an improvement in flexibility is achieved, it is not a permanent condition and can decrease quickly when stretching program is discontinued. So, keep on stretching!

 

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