Prolonged static stretching weakens the muscle or muscles that are intended or used for a specific physical activity, sport or exercise.
There are 5 ways to warm-up prior to any physical exercise or activity with the most popular ones being STATIC, DYNAMIC, BALLISTIC, ACTIVE ISOLATED stretching and MYOFASCIAL RELEASE. Muscles subjected to prolonged static stretches not only become weak but can stay weak up to 20 to 30 minutes suggesting that it not only weakens that muscle for it’s specific task but also exposes the individual to the likelihood and potential for injury, let alone suboptimal performance.
It is now conventional wisdom that before a workout or competition, it is best to perform dynamic stretching, somewhat as a method of stretching, but more as a warm up. Then after the athletic workout or competition is completed, to then perform static stretching.
(1) STATIC STRETCHING is probably the most familiar and time-honored type of stretching. This involves stretching a muscle to near its furthest point and then holding that position for at least 15 to 20 seconds ( Recent studies have shown that a static stretch can be held up to 17 minutes without the danger of straining or forcing the muscle into spasm). The emphasis of STATIC STRETCHING is often to focus on a single muscle group with each stretch.
Why does STATIC STRETCHING cause muscle weakness?
Warm-up stretching is usually performed before an exercise with the aim to reduce the risk of injuries and improve performance.There have been controversial studies that have shown that although static stretching of a muscle-tendon (myofascial) unit temporarily improves joint range of motion (ROM), the static stretching can also temporarily impact the muscles’ ability to exert maximal force, in other words, static stretching can temporarily weaken the muscle.
* ABSTRACT
Research from the School of Health and Sport Sciences, Chukyo University, Japan, studied the viscoelasticity of the medial head of the gastrocnemius muscle-tendon unit after stretching. The term viscoelasticity, synonymous with the term elasticity is defined as the ability of a soft tissue to return to its normal length after it has been stretched, in other words, after it has been lengthened.
Two studies were conducted :
Study – Elasticity of the Muscle
Eleven males participated in the study. For 5 consecutive days, passive dorsiflexion of the ankle range of motion (ROM) was assessed at the following intervals relative to the stretching that was performed :
* Before (baseline)
* Immediately (0 minutes) after
* 15 minutes after
* 30 minutes after
* 60 minutes after
* 90 minutes after
The test involved passively dorsiflexing the foot at the ankle joint at the rate of 1 degree per second until end ROM was reached. This end ROM stretch position was then held for 1 minute. This stretching protocol was repeated 5 times. Two factors were measured.
* Ultrasonography was used to measure the displacement of the myotendinous (muscle-tendon) junction of the medial head of the gastrocnemius during the passive dorsiflexion test. In effect, this measured the lengthening stretch of the muscle.
* An isokinetic dynamometer was used to measure passive torque, in other words the muscle’s stiffness or resistance to stretch during the passive dorsiflexion test.
Results
* End ROM was significantly increased at 0,15, and 30 minutes after stretching as compared to pre-stretching (baseline) ROM. Hence the lengthening achieved as a result of the stretching maintained for up to 30 minutes after the stretching was performed.
* Passive torque resistance at end ROM was significantly decreased after stretching. However, this reduced passive torque stiffness/ resistance of the muscle-tendon unit remained for only 15 minutes, after which the muscle’s pre-stretch stiffness / resistance returned.
The results showed that the length of the muscle and the resistance to stretch of the muscle both decreased as a result of the stretching.
Study – Stretching and Muscle Weakness
The authors conducted a second study to clarify the time course of the stretching-induced decrease in maximal isometric plantar flexion torque.
Nineteen women participated in 2 randomly ordered groups. The treatment group was statically stretched for 5 minutes; the control group has no stretching performed. The participants performed isometric maximal voluntary contractions (maximum strength contractions) of the right plantarflexor muscles. Electromyographic (EMG) amplitude was calculated for the medial and lateral heads of the gastrocnemius
(EMG measures the nervous system’s ordering of the muscle contraction). Measurements were conducted preintervention; immediately after intervention; and at 5, 10, 15 and 30 minutes postintervention. As with the first study, the static 5-minute stretching trial consisted of dorsiflexion to the end of the range of motion and holding that position for one minute; this was repeated 5 times. The individuals in the control group rested for 5 minutes.
Results
Results showed the the maximal voluntary contraction torque was significantly decreased immediately after, and 5 minutes after the static 5-minute stretching compared with the preintervention value. But this change recovered within 10 minutes. Meaning that the loss of strength after static stretching was recovered within 10 minutes. Meaning that the loss in strength after static stretching was recovered by 10 minutes post-stretch. Meanwhile, the EMG amplitude did not change from preintervention to postintervention under any condition.
Why Does Static Stretching Weaken a Muscle?
Two primary hypotheses have been proposed to explain the stretching-induced force deficit, in other words, the muscle weakens…
Neural Hypothesis
The first hypothesis was that a neural factor was involved in the stretching-induced weakness, and this caused the decreased muscle activation and reflex sensitivity (in other words, the muscle was inhibited from contracting). The neural effect can be evidenced if there is a decrease in muscle EMG. This study showed no significant changes in EMG amplitude. Therefore, the neural factor was discounted as the primary effect in the stretching-induced muscle weakness.
Mechanical Hypothesis
The second hypothesis assumed that a mechanical factor caused a decrease in stiffness of the muscle-tendon unit that may have affected the muscle’s strength via the length-tension relationship. The length-tension relationship describes the relationship between muscle’s length and the tension that the muscle can generate, in other words its strength. The length-tension relationship shows that the active contractile strength that a muscle can generate is greatest at resting length, but decreases if the muscle is either shortened or lengthened.
Decreased stiffness of the muscle-tendon unit after static stretching may increase the resting length of the sarcomeres, which in turn may alter the length-tension relationship, thereby decreasing the maximal force-producing capabilities of the muscle. Furthermore, the deformation of the connective fascial tissue aspect of the muscle may also play a role. This study demonstrated the decrease in the rate of torque (muscle strength) immediately after stretching compared with that at pre-stretching. In addition, the study also showed that a reduction in stiffness of the muscle immediately after a 5-minute static stretching ( ~13 and 22 %, respectively) and 5 minutes after stretching (~17 and 30%, respectively).
Overall, these results suggest that the mechanical property of the muscle-tendon unit may be a major contributor to the stretching-induced weakness of the muscle.
(2) DYNAMIC STRETCHES are active movements where the joints and muscles go through a full range of motion. They ca be used to help warm up the body before exercising.
Dynamic stretches can be functional and mimic the movement of the activity or sport you’re about to perform. For example a swimmer may circle their arms before getting into the water.
Dynamic stretches can also be a series of movements to get the body moving before any type of exercise. Some examples include trunk twists, walking lunges, or leg swings against a wall.
Dynamic stretching moves arterial and venous blood, as well as lymph fluid and synovial fluid. If performed actively, as it usually is, it also facilitates neural pathways and strengthens the muscles that are contracting for the movement
(3) BALLISTIC STRETCHING is a warm-up stretch method that involves quick and sudden movements to increase flexibility. It is mainly used by athletes and people who exercise in a daily basis to increase muscle power and range of motion (ROM). It is done by bouncing and using momentum to do a hyperextended stretch.
Potential benefits of ballistic stretching …
* Stretching beyond stretching techniques
* Improved tendon elasticity
* Less soreness than static stretching
* Increased levels of blood circulation.
(4) ACTIVE ISOLATED STRETCHING
This unique form of stretching was created by a kinesiologist to improve flexibility, reduce pain and improve a person’s exercise performance without the risks of injury. Active Isolated Stretching (AIS) can be divided to up into 3 parts.
The first involves isolating the muscles you are stretching by flexing one muscle to stretch the other one. For instance, to stretch your quadriceps, you need to flex your hamstrings.
For the second part, you will flex, but only for a period of 2 seconds.
The third step of the process is to perform this 10 times. So, the whole process is doing 10 shot repetitious holds, rather than one long like with static stretches.
Each time you do these flexes, make sure to breathe in before and exhale during the stretch. This is the proper way of breathing, which pumps more oxygen through the body and increases your circulation. These stretches are completely safe to do on your own once you’ve learned the proper technique.
(5) MYOFASCIAL RELEASE
While technically a type of stretch, myofascial release is used as a type of physical therapy. The process is meant to ease and relieve tension and tightness in the area known as a trigger point. This is why most of these treatments are only done during a professional massage therapy session. It is mostly used on people who suffer from myofascial pain syndrome. The name is a technical way to describe muscle pain. It specifically refers to pain and inflammation in the soft tissues of the body. These are the connective tissues that cover our muscles. The treatment process involves a therapist gently massaging the myofascia to feel for any areas that might be stiff or tight. The massage is performed through the application of manual, light pressure. The process can be repeated on the specific trigger point until the therapist can tell they’ve released all the tension.
* References :
Understanding Muscle Pain, Fascia, and Myofascial
Brent Bauer, M.D., Mayo Clinic, August 6, 2021
ReleaseStudy – Stretching & Muscle Weakness
Journal of Strength and Conditioning Research, January 2014
Stretching : The Truth
Phys Ed / The New York Times, October 31, 2008
The Importance of Stretching
Harvard Health Publishing / Harvard Medical School, March 14, 2021
