Crick of the muscles of the back of the thigh is one of the most common injuries from exercise. It occurs in 12-16% of athletes, while the frequency of repeated injuries reaches 22-34%. Usually, people advise stretching before a workout to avoid crick.
Such injuries usually occur during sports, which include sudden acceleration or deceleration and fast running. They are associated with eccentric contraction of the hamstring muscles, which occurs in the final phase of movement and contributes to the slow extension of the knee. To avoid injuries, muscles are most often stretched before training. But does it help?
Does Stretching Before Workout Help?
Recall that a lack of elasticity of the muscles of the posterior thigh can lead to muscle imbalances, which, in turn, provokes injuries of the musculoskeletal complex, tendonitis of the knee joint, patella-femoral pain and the appearance of pain in the lower back.
Stretching before workout is often performed during a warm-up (before basic exercises) to increase joint mobility – the ability of a joint to move in all planes with a full range – to reduce muscle and tendon rigidity and optimize movement. Athletes practice various methods of stretching, such as:
- static – all exercises are performed statically;
- dynamic – exercises are performed dynamically but in a controlled manner;
- ballistic – dynamic, uncontrolled, sharp, jerky exercise;
- PNF (proprioceptive neuromuscular facilitation) – exercises in which through resistance the muscle, being in an elongated state, strains, and then passively relaxes.
It is believed that it is static stretching, in which the target muscle is held in an elongated position for a certain period, reduces the rigidity of the muscle-tendon complex and increases tolerance to stretching. But researchers have concerns that static, ballistic stretching and PNF can reduce muscle strength, the number of repetitions, and the height of a vertical jump. It is noticed that if static stretching is used as the only tool, it can do much harm.
It is known that it is the dynamic stretching, in which the stretched part of the body moves along the entire possible range of motion through the work of antagonists, increases muscle strength, short-distance running speed, the result of a vertical jump and the quality of hitting the ball in golf.
As a result, dynamic stretching has become recommended for warming up before training.
However, while some studies show that dynamic stretching improves joint movement, others speak of its effect on the rigidity of the muscular-tendon complex. In addition, it was suggested that the increase in the amplitude of motion in the joint observed after dynamic stretching is due to adaptation to stretching, and not a decrease in the rigidity of muscles and tendons.
Since stretching exercises are usually performed 15-60 minutes before the start of competitions or physical exercises, it is important not only to find out the effect of dynamic stretching on the stiffness of the muscular-tendon complex and tolerance to stretching but also to study their long-term effects.
Scientists conducted research whose purpose was to study the effect of dynamic stretching of the hamstring muscles on the amplitude of passive extension of the knee, on the torque in the knee joint until pain appears (as a measure of tolerance to stretching) and on the passive stiffness of the muscular-tendon complex for a long period after stretching.
Researchers have suggested that dynamic stretching performed before basic physical exercise specifically improves the functioning of the hamstring muscles by increasing the amplitude of knee extension, torque, and reducing passive stiffness. And also, that the effect on passive stiffness will not last as long as changes in extension amplitude and torque.
Scientists selected 24 healthy people aged 20 to 23 years and sequentially assigned either to the experimental or control group – 6 men and 6 women in both groups, similar in such parameters as age, height, weight, and BMI. All participants were selected on the basis of a screening test, which confirmed that they could not completely straighten the knee from its original position (Figure 1).
There were no differences between the groups in the average angles of hip flexion and knee flexion at the beginning of the experiment.
Figure 1. (a) Position for testing passive extension of the knee using an isokinetic dynamometer. The left figure is the starting position, where the knee and hip joint are approximately 110 ° flexion. Right figure – the knee is passively unbent until the subject feels pain (maximum knee extension). b) curves showing data before and after dynamic stretching. The stiffness was determined using a regression line between 50% and 100% of the ratio of the ranges of the amplitude of motion and torque in the knee joint to stretching
Potential participants who underwent surgery on TBS or joints of the lower extremities, having neurological abnormalities in the lower extremities, taking hormones and / or medications that could affect the functioning of their muscles, were suspended.
Also, there were no athletes among the participants.
The stretching before workout study participants were advised not to change their habits and to refrain from physical exercise two days before the start of the study. The experiment was conducted in a university temperature-controlled laboratory at a temperature of 26 ° C.
The amplitude of passive extension of the knee, torque before the onset of pain, and passive stiffness of the muscles of the posterior thigh were measured using an isokinetic dynamometer before and after dynamic stretching, as shown in Figure 1.
Measurements were taken in the experimental group before dynamic stretching (pre) and after a time – 0, 15, 30, 45, 60, 75, and 90 minutes after dynamic stretching (post). Similar data were taken in the control group, the participants of which did not do dynamic stretching.
The effect of dynamic stretching before workout
Each study participant dynamically stretched his right leg. It was dominant in all 24 participants in the experiment – with the help of a survey, it was found out that all of them kick a soccer ball with their right foot.
Figure 2. A – initial standing position; B – contraction of the hip flexors
The warm-up was excluded to avoid any effect on stretching. Participants were asked to stand upright, place their legs parallel to each other, and hold the parallel bars with both hands (the initial standing position). Then the subjects were asked to lift their legs to reduce the hip flexors, without bending the knee, every 2 seconds (the muscles of the back of the thigh stretch).
Each participant performed 5 slow repetitions of this exercise in order to master the technique. Then they performed 10 quick repetitions with maximum amplitude to the rhythm of a digital metronome set to 30 beats per minute, without bouncing. Dynamic stretching was performed for 5 minutes and included ten 30-second sets with a 20-second rest between them.
During rest, the subjects occupied the starting position while standing. It was the 5-minute dynamic stretching (DS) that was chosen because previous studies showed that 5 minutes of static stretching with moderate intensity and no pain increased the amplitude of motion and torque, and also reduced the passive stiffness of the muscles of the backbone after exercise.
Although no significant long-term changes were found in the final indicators of the control group, in the experimental group, they were present in all indicators.
- In the experimental group, immediately after dynamic stretching (DS), the passive extension was increased on average by 8.1 ° (from 6.8 ° to 11.5 °), by 10% compared with the initial values.
- A significant increase in amplitude persisted for 90 minutes and remained 9.4% more than before the DS, after 90 minutes.
- Similarly, torque increased by 9.7% immediately after the DS. However, it is worth considering that the indicators 30 minutes after the exercises were practically the same as the indicators before the exercises.
- Passive stiffness decreased by 7.9% immediately after DS, remained lower than in the control group for 90 minutes, and was 13.4% lower than before DS after 90 minutes.
Conclusions: Perform Dynamic Stretching Before Workout
Researchers have found a clear and sustained effect of dynamic stretching on several parameters of the flexibility of the hamstring muscles in healthy volunteers.
Dynamic stretching contributes to a steady decrease in passive stiffness of the muscles of the hamstring, an increase in the passive amplitude of extension of the knee, and a slower increase in the amplitude of torque in the knee joint.
Dynamic stretching of the hamstring muscles before training can help prevent common injuries since increased passive stiffness of the hamstring muscles and a decrease in the amplitude of knee extension are risk factors for trauma to the hamstring muscles during sports.
The decrease in passive stiffness after DS lasts for ≥ 90 minutes after. And after passive stretching, the decrease in passive rigidity of the triceps tibia muscle lasts 12-20 minutes, the muscles of the back of the thigh – less than 60 minutes.
More about this topic:
- Dynamic Stretching Has Sustained Effects on Range of Motion and Passive Stiffness of the Hamstring Muscles
- Importance of Stretching for Bodybuilders
- Are Stretch Marks Permanent? Why?
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