The effect of flexibility training on the body

Its core function is to expand the safe range of motion of joints by improving the extensibility of soft tissues such as muscles, tendons, and fascia, helping us reduce the risk of chronic pain in daily life and sports, and optimizing the force generation mode. The sayings like "Lajin grows taller" and "the softer it is, the less likely it is to get injured" actually have applicable premises and cannot be generalized.

Two years ago, I worked for an Internet company to do sports science popularization. I met a young man who worked on the backend. He sat at his desk writing code for at least 12 hours a day. How stiff was his shoulder and neck? When I turn around to look at my colleagues behind me, I have to turn my whole upper body. I go to the massage parlor every week. I feel comfortable for two days after the massage, and immediately return to the state of "slate shoulders" on the third day. There is no organic problem in the hospital's X-ray, just muscle tension. Later, I asked him to spend 5 minutes each morning, noon and evening every day to do static stretching of the pectoralis major and PNF stretching of the scalene muscles. Simply put, PNF stretching means actively resisting the stretching force for a few seconds, and then relaxing into a deeper range. The efficiency is much higher than ordinary stretching. He persisted like this for three weeks. He came to me specifically and said that now when he wakes up in the morning, his neck will no longer be so stiff that he can't move. He can reach the folders on the top shelf of the company's shelves without causing pain in his back.

Speaking of this, some people will definitely say, I have seen before that being too flexible can lead to injuries easily? This is really not a rumor. Practitioners in different sports fields have completely different requirements for flexibility, and the controversy is not small. If you ask any old-school coach in the powerlifting community, eight out of ten will tell you not to do long-term passive static stretching before training. Why? Our soft tissue is actually like a rubber band. When it is normally elastic, it can be stretched and retracted, and can cushion the impact. If you stretch it too loosely in advance and lose the tension of retraction, the hip joint will sway back and forth when squatting with heavy weight, and you will be easily injured. A follow-up study published in "Sports Medicine" in 2021 also confirmed this conclusion: Only when your joint mobility is lower than the minimum threshold required for the sport you are engaged in, improving flexibility can reduce the risk of injury. If it has met or even exceeded the threshold, and then overstretches, the probability of injury will increase by about 30%.

Damn, I’ve seen too many people go to extremes in their understanding of flexibility training. They either think that being harder doesn’t matter, or they work hard to practice the straight line and lower the waist, thinking that the softer the body, the healthier it will be. There was a girl who followed me to practice body shaping before. In order to take a picture of a horse in the circle of friends, she asked the teacher to press her legs hard during a yoga class, which directly strained her adductor muscles. It took more than three months to recover. In fact, she usually works from 9 to 5 and runs up to 5 kilometers on weekends. She does not need such a large range of hip joint mobility. The normal range of motion can fully cover all daily needs. It is really unnecessary to spend so much time on flexibility, and she might even get injured.

Many people don't know that whether you are flexible enough directly affects whether you can find the right sense of force during exercise. I have met at least dozens of students, and they say they can’t feel anything after doing butt exercises. After squatting, their legs are sore, their waists are sore, but their buttocks are not sore. After a series of tests, they basically all have the problem of tight hip flexors - sitting and standing for a long time can easily lead to hip flexors becoming as stiff as an old towel that has been wrung out. When squatting, the hip flexors take away the space for the gluteal muscles to exert force, but they cannot train their buttocks. Generally, I ask them to spend 2 minutes doing a static hip flexor stretch before doing hip exercises, and then do two sets of clam pose activations. 90% of people can feel soreness in their buttocks on the spot, and any activation exercise is more effective. I used to suffer from calf pain when I ran a half marathon. It took me a long time to find out that the soleus muscle was not extensible enough. When I landed, the ankle mobility could not keep up, and the impact force was all on the calf. Later, I stretched my soleus muscle for 5 minutes before and after every run. In less than two weeks, the pain that had lasted for more than half a year disappeared.

There are many flexibility training methods on the market now, including traditional static stretching, dynamic stretching, PNF, and fascia relaxation. Each has its own supporters, and no one can convince anyone. In fact, there is really no need to worry about which one is best, just use it according to the situation: use dynamic stretching before exercise to warm up, such as arm swings, leg raises, and hip joint circles, which can increase mobility without reducing muscle tension. ； Use static stretching or PNF to relax after training to help the muscles return to normal length. ； If I feel stiff during work hours, I can lean on the door frame to stretch my chest for two minutes, or use a fascia gun to hit my trapezius muscles for two minutes, whichever is more convenient.

In general, flexibility training is never some "soft is better" metaphysics, nor is it a useless showmanship. If you sit in an office every day, do more exercises on your shoulders, neck, chest, and hip flexors, which are the areas most prone to stiffness. It’s enough for daily use. ； If you practice sports that require a large range of motion, such as gymnastics, dance, and martial arts, then no matter how much flexibility you aim for, don't forget to combine it with strength training of the surrounding muscles. Once you are stable and soft, you will be less likely to be injured. After all, no matter what kind of training, comfort, no pain, and smooth movement are the most practical standards.