Stretching and warm-ups have been a part of athletic training and competition from the beginning. These routines are designed to boost performance while also reducing injury and post-exercise soreness. Surprisingly, while research supports the position that warming up is critical, the evidence that stretching itself is beneficial is shaky. In fact, some stretching clearly increases the risk of injury and decreases performance. A long-term stretching program after exercise probably reduces injuries or post-exercise soreness, but this is also debatable. As a result, there is a significant shift taking place in the practice of stretching. This article discusses what, why, and how to stretch, as well as the role stretching should play in warming up.

What to Stretch

Stretching has an impact on the ligaments that provide joint stability, the tendons that connect muscle to bone, and/or the muscle that generates power. Stretching has also been shown to cause changes in the nervous system. Ligament stretching is generally not recommended, as explained below. Tendon stretching is time-consuming and provides little benefit. The majority of stretching occurs in the muscle.

Muscles have elastic properties, which means that they will tend to return to their original length if stretched. They are also viscous and plastic, which means that if stretched for a long enough period of time (about 30 seconds), they tend to remain lengthened and only slowly return to their original length. The viscoelastic changes that occur during stretching have been thought to be the cause of muscle lengthening. However, some of the changes are the result of lower pain thresholds or decreased muscle strength, which have just as many negative effects as positive ones.

Why Stretch?

Traditional reasons for stretching include increasing range of motion (ROM) around a joint, increasing muscle flexibility, and warming up the body before intense exercise. We’ll take a look at each of these potential characteristics one at a time.


The arc through which a joint can move is referred to as its range of motion (ROM). Gymnastics, for example, necessitates a large range of motion. However, simply increasing ROM around a joint is not always beneficial. Increased range of motion must be accompanied by increased muscle strength in order to protect the ligaments, tendons, and muscles from injury. This muscle strength is also required to allow use of the body in that new ROM, otherwise it serves no purpose. For example, a backstroke swimmer’s ability to externally rotate the arm so that the hand is above and behind the head is only useful if the ROM is accompanied by muscle strength and power to produce faster swimming. Much of the stretching we’ve done in the past increases ROM by stretching ligaments that may already be too loose, and actually decreases muscle power for a short period of time.

For example, having a partner pull the arms back as far as possible is a stretching exercise used by swimmers to increase shoulder external rotation. Because most swimming motions stretch the anterior ligaments of the shoulder, which limit this motion, they are rarely tight. Stretching these ligaments may have a negative impact on joint stability. Tightness in the front of the shoulder occurs when muscles such as the pectoralis major become overworked. If we want to increase ROM, we need to do it under control, preferably with the athlete’s own muscles, so that strength and power increase in tandem with flexibility of all the related muscles.

Ligaments keep joints in precise positions throughout their range of motion, and they are usually best left alone to do what they were brilliantly designed to do. They do, however, require stretching on occasion. One example is the ligaments in the back of the shoulder, which are frequently tight but the muscles are long and weak. It is critical to stretch the ligaments but not the muscles in this situation. The upper arm being forced across the chest is an exercise designed to stretch these tight posterior ligaments. However, more often than not, it only stretches the scapular stabilizer muscles, which may already be overly long. A physical therapist or athletic trainer will need to ensure that the athlete stretches precisely in order to stretch the right thing without damaging something else.


Flexibility refers to a muscle’s ability to work across its entire range of motion—both short and long. What has perhaps become more apparent in recent years is that flexibility cannot be created in a single muscle. Stiffness, which is the amount of force required to elongate a muscle, is a related property. Muscle stiffness is not always bad, but it must be balanced. It is often necessary to correct a balance of the flexibility and stiffness of opposing muscles, rather than just one muscle group. We’ve learned that there is such a thing as too much flexibility.

Even if the pectoralis muscle is carefully stretched without damaging the ligaments (i.e., it becomes more flexible), this new elongated status may only last a few minutes. One common cause is that many athletes have rounded shoulder postures as a result of hours of computer keyboarding, which is what caused the pecs to become short in the first place. It will be nearly impossible to maintain an elongated pectoralis unless the long and weak posterior rotator cuff muscles and scapular stabilizers are corrected. Longer-term solutions include stiffening (strengthening and shortening) the posterior muscles to stretch the pectoralis. This is what your mother was attempting to accomplish when she told you to sit up straight with your shoulders back.


Warming up muscles before exercise has been shown in studies to improve performance and prevent injuries. Stretching has long been considered an important part of “warming up” for exercise, but the benefits of warming up have been incorrectly attributed to stretching. Traditional stretching, according to research, is not the best way to warm up. Because the actual temperature of the muscle is probably the most important factor, sitting in a hot tub is almost as effective as warming muscles with moderate dynamic activity. Dynamic movements effectively prepare the muscles for powerful action across the required range of motion.

As a result, we must reconsider how we stretch in order to reap the benefits of increased balanced ROM, flexibility, and warm-up without the potential drawbacks or wasted time.

How to Stretch

Static stretching occurs when an athlete assumes the stretching position while using his or her own opposing muscles. Stretching can also be passive, with a partner providing the force to achieve the stretching position. In both cases, we want to stretch a muscle to the point of mild discomfort for about 30 seconds. While these actions do lengthen the muscle, there is mounting evidence that they also reduce power and speed, at least for a few minutes. According to one study, athletes who routinely did dynamic exercises improved their time for a 600-meter (m) run by 2.4 percent, while athletes who did static stretching worsened their time by 2.5 percent. Ballistic stretching, which entails swinging a body part to force a joint into an extreme range of motion, activates some neurological reflexes and may increase the risk of muscle damage.

The technique currently recommended is dynamic stretching. Because this involves dynamic movements rather than static positions, it may not appear to be stretching in the traditional sense. Overload movements, such as weighted jumping, show even more promise. This stimulates the nervous system, whereas static stretching suppresses it. As previously stated, ballistic stretching activates the nervous system, but most likely in a negative way. Passive stretching, which stretches more ligaments than muscles, should be used with caution, if at all.


Let’s look at how we might approach tight hamstrings to demonstrate how these various types of stretching might be used. Passive stretching would include having the athlete sit with legs extended and having a partner push on the athlete’s back. There is a risk that this will increase ROM, but by stretching back the ligaments, which increases the risk of back pain, there will be little improvement in tight hamstrings. Passive stretching would be having the athlete sit with his or her legs extended and his or her head on the knees. If done correctly, this will result in increased hamstring length at the expense of short-term decreased hamstring strength and power.

Ballistic stretching would be standing on one leg and swinging the other to the limit of ROM. This may result in tears without significantly increasing muscle flexibility. Dynamic stretching would entail active movements like striding, lunging, or whole-body movements similar to the sport itself, all while maintaining a stable lower back and pelvis. This type of movement is frequently used in Tai Chi, yoga, and pilates. It is also the essence of “core” training, which is essential for overall musculoskeletal health. Dynamic stretching results in a long-term rebalancing of muscle strength, flexibility, and stiffness while causing no ligament damage.


What one well-known physical therapist refers to as the “tail wagging the dog” is an example of how stretching is related to core strength. Because the back and pelvis (core) are not strong enough to stabilize the leg motion, athletes with strong legs may produce unwanted motions and pain in the back and pelvis. The core muscles are less stiff (more flexible) than the leg muscles in this situation. The long-term solution to stretching “tight” leg muscles is to strengthen the core muscles. It is nearly impossible to achieve such rebalancing through isolated stretching of the leg muscles, whereas real-world movements of dynamic stretching performed with proper form will result in a practical balance of flexibility.


Warming up before exercise is still very important, but stretching, at least passive or static stretching, serves little to no purpose in a pre-exercise routine. It may have limited benefit after exercise, but it has little negative effect. Warming up should consist of moderate activity similar to the sport to be performed. Muscle flexibility and range of motion are best improved with a long-term training program. Muscle strength and power are gradually developed over the required ROM by working from a strong core. This usually entails sports-like activities that focus on form rather than force.

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