The relationship between fitness and kinesiology

The essence of fitness is the implementation of kinesiology theory in the context of mass body management and competitive ability improvement. Kinesiology is the underlying support for fitness action design, efficiency optimization, and risk avoidance. The two are by no means a one-way upward-subordinate relationship of "theory guides practice", but a symbiosis of two-way penetration and mutual modification from the laboratory to the gym, from elite competition to ordinary enthusiasts.

Last week I was squatting in the community gym. As soon as I set up the bar, I heard the instructor next to me yelling at the students: "Don't let your knees go past your toes! Don't understand? ”The student's face was red from holding it in, his waist was bent almost parallel to the ground, and he didn't dare to move his knees forward. I felt sweat on his back just looking at him. This is actually a typical misunderstanding that many people have about the relationship between the two: either they regard the scattered conclusions of kinematics as rigid rules that cannot be touched, or they think that "as long as I practice well, the theory is empty."

In the past two years, I had dinner with the physical trainer of the provincial track and field team. He said that in the previous ten years, the strength training in the team had all followed the bodybuilding template. Barbell squats must be squatted until the thighs are parallel to the ground, and the knees should be strictly controlled not to exceed the toes. As a result, several members of the sprint team had herniated lumbar discs that year, and their performance was stuck for more than half a year. Later, the team introduced motion capture equipment and analyzed the running mechanics based on the kicking and stretching movements of sprinting. It was discovered that during sprinting, the athlete's knees are 3 to 5 centimeters higher than the toes, and the hip angle is much smaller than traditional squats. The rigid squat standard does not train the specific muscle groups required for the sport, and also forces the lumbar spine to compensate. Later, they switched to angled single-leg box squats and weight-bearing hip hinges. Within three months, the team members' average 100-meter time improved by 0.2 seconds, and the recurrence rate of back injuries dropped by 70%.

Interestingly, the topic of "can the knees pass over the toes", which has been debated for almost ten years, is itself a reflection of the differences in the research directions of different branches of kinematics. Traditional sports biomechanics research starts from a single joint load. Tests have found that when the knee exceeds the toe, the pressure on the patellofemoral joint will be about 30% higher than when it does not exceed it. Therefore, this limit was mentioned in early rehabilitation guidelines. ； However, functional kinematics, which has emerged in recent years, is based on the overall kinetic chain of the human body. Subsequent studies have found that if the knee is deliberately restricted from moving forward, for people with insufficient foot dorsiflexion and poor hip joint flexibility, the shear force of the lumbar spine will increase by 45%. The balance between the two phases will cause more harm to the waist. Both conclusions are supported by large sample experimental data. There is no absolute right or wrong. It is just that the applicable scenarios are different: people who have old knee injuries and only do light weight training on a daily basis, try to control the forward movement of the knee and there will be no problem. ； But for those who already have poor dorsiflexion and want to do heavy squats, trying to stick to this rule is simply asking for trouble.

Don’t think that kinesiology is just a superior laboratory theory. In many cases, it is the practitioners on the front line of fitness who first figure out the rules, and then the academic community follows up and conducts research to supplement the evidence. In the early decades, the unified conclusion of the sports science community was that "the optimal load range for muscle hypertrophy is 8-12RM." This conclusion has been used for almost half a century. As a result, in the past ten years, the "failure set" with light weight and high repetitions has become popular in the bodybuilding circle. Later, some people also developed the "strength muscle-building method" with heavy weight and low repetitions, and a large number of enthusiasts have developed obvious muscles. Dimension, the academic community went back to do muscle fiber testing, and finally revised the conclusion: the proportion of muscle fiber types directly determines the optimal load. For people who are born with a high proportion of fast-twitch muscle fibers, the muscle-building efficiency of heavy weight training at 4-6RM is 30% higher than that of 12RM. For people with a high proportion of slow-twitch muscles, light-weight training at 15-20RM is more effective. Now this conclusion has been included in the new version of exercise physiology textbooks. To put it bluntly, it is front-line fitness practice that pushes the theory forward.

To be honest, if you only exercise to sweat and reduce stress after get off work, then there is no need to chew through kinesiology textbooks as thick as bricks. Pick an exercise you like. Moving is better than sitting. But if you want to avoid injuries, want to see training results quickly, or even want to hit a marathon PB or win a small prize in a bodybuilding competition, understanding some basic knowledge of kinesiology can at least help you avoid 90% of fitness pitfalls, and you don’t have to listen to the nonsense on the Internet about "losing ten pounds in seven days" and "building a peach butt in a month." After all, in the final analysis, kinesiology studies the laws of the human body, and fitness is the process of finding out the laws of your own body with your own hands. The two are inherently intertwined and cannot be separated.