Proponents of stretching claim it helps prevent injuries, prevents soreness, improves performance, promotes body awareness, stimulates blood flow, and is mentally relaxing and centering. Opponents argue that stretching is a waste of time, can actually cause injury, and does nothing to improve performance or prevent soreness or injuries. Each side has a multitude of studies, reports, and anecdotal evidence to support its claims. While researchers advance the scientific investigation of stretching, the discussion regarding the benefits versus the risks of stretching continues on the playing field and in gyms, training rooms, and sports clinics.
Supporters of stretching generally agree that in the best of all possible exercise schemes, the athlete warms up, stretches, exercises, stretches again, and then cools down.
The physiological evidence is clear that warm muscles stretch more effectively than cold ones. A warm-up entails 10 to 15 minutes of light activity, similar to what the exercise or sport will be. This light activity increases blood flow to the muscles and gets them ready to work. Warming up also helps reduce stiffness, making the muscles more supple, so they stretch more easily (Bishop 2003a, b).Grant (1997) discusses other benefits of warming up, including increased production of synovial fluid to lubricate joints, increased oxygen exchange in the muscles, increased rate of nerve transmission, and more efficient cooperation of the muscles around a joint. By warming up first, stretching exercises will be more effective and efficient, the athlete will make greater gains than if stretching cold, and the risk of injury from stretching is greatly reduced.
In an ideal world, stretching would be included as part of the warm-up before exercise and as part of the cool-down after exercise. The reasoning behind stretching twice goes like this:
Stretching the muscles before a workout gets them ready to perform at their optimal length. This optimal length allows the muscles to develop the most power as they work. There is a preponderance of evidence that some types of stretching immediately before athletic activity may decrease explosive power and speed (Simic, Sarabon, and Markovic 2013; Behm and Chaouachi 2011). Research on the effects of preactivity stretching on endurance has not been definitive. Erring on the side of caution, most fitness professionals now recommend that preactivity stretching be confined to dynamic stretching as part of an overall warm-up routine.
Stretching the muscles after exercise while they’re still warm brings them back to their optimal resting length. As muscles work they repeatedly contract and shorten, and they tend to stay short when the workout is over unless they’re stretched again to their normal resting length. Postexercise stretching can be incorporated into the cool-down.
If time is limited, we recommend skipping the preexercise stretching and concentrating on postexercise stretching. When preexercise stretching is eliminated, the warm-up routine before the main workout needs to be thorough. Postexercise stretching will return tight, tired muscles to their normal resting length as you go about the remainder of your daily activities. In postexercise stretching, there is some danger of overstretching the muscles because they may be too pliable. But if postexercise stretching is done with awareness, the risk is minimal and is far outweighed by the benefits.
We believe that stretching must be completely comfortable to be effective. In our experience, many people stretch incorrectly, believing that if something doesn’t hurt a little, it’s not working. It’s a variation on the "no pain, no gain" mentality of exercise. Stretching until it hurts triggers the nervous system’s natural response to pain: The muscle will resist lengthening to prevent possible injury to the tissue being stretched.
We advocate stretching the muscle just to its soft-tissue barrier - that is, the point at which you begin to feel some resistance to further stretching but no discomfort. The soft-tissue barrier is the starting point for the stretch.
"Stretch without pain" also applies to the rest of the body during a specific stretch. Even if you have no pain in the muscle you’re stretching, pain or discomfort elsewhere in your body will negatively affect your results. For example, if you’re having low back pain while you stretch your quadriceps, you won’t be able to relax and fully engage in the stretch. Repositioning to relieve your back pain makes the quadriceps stretch more effective.
Experienced stretchers are acutely aware that flexibility varies from day to day and from joint to joint. It’s important to take each day as it comes and stretch as best you can. Just as those who change their diets to lose weight are advised not to step on the scale daily, you cannot measure improvement in flexibility daily; you are better off looking at your gains over the long term.
Stretching tight muscles is a pleasurable activity when done correctly. But not all tight muscles need to be stretched. Some are already overstretched and need to be strengthened instead. The following paragraphs deal with the differences between hypertonic and eccentrically stressed muscles, called crossed syndrome, and the effects of neurological inhibition on muscle balance. This is a brief discussion of a complex topic, which we urge you to explore more fully in other writings devoted to the subject (Lewit 1999; Chaitow 2006; Liebenson 2006).
- Hypertonic muscles. When a muscle is short and tight because of habitual concentric contraction, it’s called hypertonic. Myers (2008) refers to this as "locked short." A good example of short and tight can be found in the pectoralis major. Because most of us spend so much time sitting in front of computers, driving, or doing other activities that use our arms in front, the pectoralis muscles can become chronically hypertonic. Hypertonic muscles tend to feel fat or thick and tight to palpation. Stretching these muscles can help restore them to normal tone and length.
- Eccentrically stressed muscles. When a muscle is overstretched (usually due to postural stress), it will also feel tight; but instead of being short and tight, it is long and tight, or "locked long" (Myers 2008). It stays in a state of eccentric contraction, in which it constantly works to try to return to its normal length. The rhomboids provide a good example of muscles under eccentric stress. Most of us tend to be a little round shouldered. Hypertonic pectoralis muscles contribute to this posture. As a result, the rhomboids, which attach to the spine and the shoulder blades, are always fighting to counteract the force of the pectoralis muscles and pull the blades back to their normal position. The resulting eccentric stress causes the rhomboids to feel tight and sore to palpation. Muscles under eccentric stress tend to feel thin or stringy and tight. The correction for this condition is not to stretch the rhomboids but to strengthen them and to stretch the pectoralis muscles to restore balance between the chest and the back.
- Crossed syndrome. Similar patterns of muscle imbalance can be found elsewhere in the body. Czech researcher Vladimir Janda (1983) describes these patterns of imbalance as upper and lower crossed syndromes (figure 1.11).
- Muscle weakness due to inhibition. Even though Sherrington’s law of reciprocal inhibition does not universally apply as previously believed, our experience with patients has taught us to act as if hypertonic muscles have a reflexive inhibitory effect on their opposing muscles. To use the pectoralis muscles and the rhomboids again as an example, when the pectoralis muscles are locked short, they not only contribute to the eccentric stress on the rhomboids by mechanically pulling against them but also appear to neurologically inhibit the rhomboids, making them less able to exert their normal strength to maintain postural balance. It is common to find that the rhomboids regain much of their normal strength and tone spontaneously after the pectoralis muscles are released through stretching. The same scenario is seen in many areas of the body. Because of this, we believe that stretching work should precede strengthening when one is trying to correct postural imbalances.