This is definitely all true, but that’s about it! Everywhere you look, whether in gyms, courses at adult education centers, or sports clubs, even in articles, books, or on television, it seems like everyone is telling you that you absolutely must stretch after exercising or strength training. It’s said that stretching accelerates recovery, stops sore muscles, and prevent injuries.

“It's all nonsense,” says Professor of Kinesiology Dr. Jürgen Freiwald, an often-cited and distinguished expert in the field of “stretching” from the University of Wuppertal. “There is absolutely no scientific evidence supporting these claims.”

We take a closer scientific look at the myths surrounding stretching in the following:

1. Stretching Improves Flexibility?

A resounding YES! Stretching can significantly improve and maintain flexibility. Other options available to enhance flexibility include fascia treatments, massages, foam rolling, or strength training at a full range of motion (ROM).

If flexibility is not improved through regular stretching and extension and the muscle continues to tighten, assume that there is a muscular imbalance (Freiwald, 2009). A muscular imbalance is when one muscle tries to assume the task of another muscle, is thereby overstrained, and ends up in a state of constant tension. Stretching itself cannot remedy such tension, but it can often alleviate the symptoms and make it easier to address the underlying causes, which must be identified through special tests. The problem is usually caused by the tense muscle’s antagonist and synergist weakening or not working properly.

2. Only Stretch Once You’ve Warmed Up?

Yes! However, you do not have to warm up muscles in the traditional manner by doing cardiovascular exercise. A simple yet excellent way of preparing tissue for stretching is to massage it using a foam roller! Knots can thus be loosened and both the muscles and connective tissue massaged.

Knots or trigger points in the muscles are comparable to a knot in a rubber band. The knots only become tighter by pulling the band.

A real-life example:

Michael Boyle, one of the most successful American strength and conditioning coaches in elite professional sports, begins all his workout sessions in the following manner:

• Foam rolling
• Static stretching
• Dynamic activation

He has managed a soccer team for 11 years now without a single one of his players tearing a cruciate ligament.

3. Stretch When You Have Muscle Tension?

Yes, if it does you good! The muscle’s resting transmembrane potential is not reduced in the long term by stretching but rather increased in many cases (Klee, 2003). Still, active stretching methods can provide short-term relief, for example, when you have neck tension or back pain. The cause, however, is rarely rectified. Tension or increased muscle strain is a protective mechanism and can easily be triggered again if no further action is taken.

Even if there is no definitive scientific proof to support that it has a relaxing effect, there is a subjective perception that: You should stretch if you personally believe that it helps you! Specific strength training must also be done to prevent long-term back and neck pain (Wiemann et al. 1998).

4. Stretching Prevents Injuries?

Yes, if you’re extremely restricted in your movements! Specific stretching carried out in tandem with strength training can protect against injuries if it eliminates such movement limitations. In two studies, the American sports medicine specialist Dr. Knapik and his colleagues were able to show, for instance, that athletes are 2.6 times more likely to suffer injury if they have a difference of greater than 15% between the left/right hip extension. Further studies proved in general that all left/right asymmetries considerably increase the risk of injury. Targeted stretching that enables symmetry and balance can definitely reduce the risk of injury(Knapik et al. 1991, 1992).

Office workers, for example, are generally at risk because the hip flexors are almost always “shortened” or the hip extension is restricted from having to sit all day. Sprinting, running, and also walking (whenever the leg is brought behind the upright position) can cause you to go into a swayback posture in order to compensate (hollow back), which can lead to prolonged injuries and chronic pain.

Do not stretch before sports. In March, a group of researchers from the American College of Sports Medicine analyzed the most important studies and reconfirmed that none of the classic stretching techniques protect against injuries. “Nevertheless, this is probably not the last word on this matter,” says Freiwald. The reason for this is that studies contain systematic sources of error. For instance, they often counted all injuries, even those having nothing to do with stretching (e.g. a kick to the heels). They also didn’t take into consideration whether test subjects had warmed up properly. “That is the most important thing to avoid injuries,” says Freiwald. Recently developed dynamic methods of stretching and flexibility exercises, including “movement preps”, “active isolated stretching,” or yoga exercises, have also not been studied in this context.

There is definitely a higher risk of injuring yourself if you do passive/static stretching immediately before exercising without following it up with an activation phase because joint stabilization is briefly diminished. This, however, does not affect strength training and gym-based workouts.

5. Stretching after Sports or Strength Training Prevents Sore Muscles?

A resounding no! Freiwald: “Intensive stretching after physical activity can even make muscles sorer.” To recover, blood circulation must be encouraged, for example, with a soak in the sauna, gentle massages, or hot and cold showering. Static stretching has exactly the opposite effect. Blood flow to the muscle is already significantly impaired by stretching by 30% due to the constriction of the blood vessels.

To prove this, Freiwald had 78 test subjects carry out 150 strenuous burpees. A quarter of them then stretched the trained muscles with static stretches, a quarter did dynamic stretches (with deeper stretching), a quarter walked at a relaxing pace, and the remaining quarter simply laid down and did nothing. The levels of lactic acid in the blood and muscle relaxation levels were then measured. The result confirmed what the researchers had feared—static stretching delayed the breakdown of lactic acid and thus muscle recovery. Dynamic stretching didn’t have a negative impact. It didn’t seem to help either. Only walking off the workout had a positive effect on recovery!

6. Stretching before Sports and Strength Training Prevents Sore Muscles?

No! Stretching before working out also does not prevent sore muscles, as proven by tests where athletes had to stretch one leg and not the other. They either had no sore muscles at all or sore muscles on both sides after exercising (High et al. 1998).

7. Stretch Muscles during the Rest Interval?

No! Stretching the muscles, which are being trained, during the rest interval makes absolutely no sense at all. Contract the muscle as far as it goes first and then tear it apart again? No, that’s dangerous! After exhausting sets, there are contraction residues (muscle fibers that are still contracted) that cannot be loosened by stretching without being damaged. The rationale that muscles supposedly shorten during working out and are lengthened by stretching is also false. Muscle length is genetically predetermined and proportional to the bone length. Neither static stretching nor mobilization (e.g. arm circles) during the rest interval improves your performance during the following set. Instead, they reduce it (Thienes, 2003).

8. Stretching Helps Sore Muscles?

No! Stretching does not reduce the pain of sore muscles. Instead, excessive intensity causes even more damage. Very gentle stretching can, however, help to stimulate and speed up the proper redevelopment of muscle structures. That can relieve sore muscles, but it’s especially effective in accelerating the rehabilitation of torn muscle fibers, strains, and surgical scars. Relaxed movements or very gentle strain exerted on muscles during endurance sports also facilitates the proper alignment of muscle fibers and reduction of pain through improved blood circulation.

9. Stretching Improves Performance?

No! Performance is not improved by stretching before working out or competing. The opposite is quite true. Many studies showed that maximum strength was reduced by 4–20% and power decreased between 3–10% with passive/static stretching (Avela et al., 1999), which makes you even more sluggish sprinting or changing direction, for example. Thienes (2003) also demonstrated that muscular endurance was negatively influenced by passive/static stretching and mobilization exercises during the rest interval.

On the contrary, a study has demonstrated that dynamic stretching had no negative impact on peak performance and power (Begert & Hillebrecht, 2003). Active/dynamic stretching also serves to activate the muscles, tendons, and ligaments over the full range of motion. If you cannot move freely or if you are playing a sport requiring a high degree of flexibility, active/dynamic stretching methods (e.g. movement preps) should be predominantly used.

To Stretch or Not to Stretch?

There is no need for you to stretch if you don’t have any issues or pain and you don't want to change your physical activities. “You can have a clear conscience about not stretching throughout your (active) life,” says Dr. Jürgen Freiwald.

Stretching is recommended for the following people engaged in athletic activities:

• Athletes who have limited mobility and therefore make compensation movements during basic activities or sports (e.g. when bending down or running). Movement tests (e.g. functional movement screening [FMS]) identify limitations and compensation patterns. Ask your trainer/coach about this!
• Athletes in sports require a very high level of flexibility (e.g. gymnasts, martial artists, etc.).
• Athletes with left/right asymmetries
• Athletes who have some very flexible and some very stiff muscle groups (imbalance) – e.g. excessive mobility in the back of the thigh, with limited flexibility of the adductors.