If you love running, you must read this! How to protect your knees during long-term running?

Speaking of running, as someone who has been running for more than a year, I have something to say. The reason I chose running was because I felt my body was empty, er, no, my body was filled. I sat in front of the computer every day, and except for eating and walking a few steps, I didn’t do any other exercise (don’t think that doing biology means sitting around the test bench all day long. In fact, quite a number of people are responsible for processing data, such as me). The result was a sudden increase in weight, and I had to gain a few pounds during festivals throughout the year... What can I do? I am also desperate!

My idea at the time was: either diet or exercise. I won’t say much about dieting, it’s all tears, but I did stick to running. However, exercise brings up another question: will running damage my knee joints? Although fitness coaches and various sports apps are talking about sports injuries, are they true? Is there any evidence (doing scientific research, we must pay attention to the scientific spirit~)? As a stubborn person, I am the kind of person who only looks at science, so I read a lot of literature to see other people’s research, and today I will share my findings with you.

01. It is not exercise that damages joints, but "excessive exercise"

Exercise does cause damage, but the human body has a strong resistance mechanism. After all, it has evolved for so many years. If it doesn’t even have the ability to resist exercise, wouldn’t everyone have arthritis? There are even studies showing that the human knee joint is strong enough to withstand a pressure of 25 MPa without obvious damage.

Figure 1, Schematic diagram of the buffer system of human joints

Unfortunately, many people exercise too much, which can cause damage to the knee joint. Excessive exercise here includes two aspects.

1. Excessive exercise intensity: Exercise exceeds personal tolerance, such as a person who rarely exercises suddenly doing long and large-scale exercise

2. Overweight: The load of exercise itself exceeds the individual's tolerance. This situation is very important for people who are too heavy. Being overweight or obese puts a huge pressure on the joints. For people who are too heavy, the impact on the knees is too great, and running can cause serious injuries. Therefore, it is not recommended for obese people to lose weight by running at first, but to carry out initial weight loss activities through controlling diet and other auxiliary exercise methods.

This is a diagram of a pressure injury model:

Figure 2, mild and severe pressure injury model

We can see that the effects of high loads and low loads are different . When high loads, such as being overweight, or strenuous exercise create impact, the cartilage will actually be under tremendous pressure, making it more susceptible to damage.

In fact, the stress caused by walking and running is completely different.

Figure 3. Changes in joint stress during walking and running

This is the change in joint pressure caused by walking and running. We can see that walking basically maintains a normal state with small pressure fluctuations, but running has extremely drastic fluctuations. So, if you imagine an overweight or even obese person running, the damage to his knees is simply unimaginable.

So are we unable to avoid sports injuries?

02. How to run scientifically?

If you regard running as a hobby or a standard fitness model, then you must pay attention to the following contents.

Figure 4 Schematic diagram of running

1. Exercise in moderation. As mentioned earlier, excessive exercise can cause joint damage, so what is moderate exercise?

First of all, if you run for health, you can run 3 times a week, each time running 5 to 8 kilometers.

If you are training for a marathon, you can look at your monthly running volume:

Monthly running volume: The basic monthly running volume for marathon training is based on 200 kilometers, so if your monthly running volume is between 200 and 300 kilometers, you only need to run every other day; for example, if you run 3 times a week, 2 times of 10 to 12 kilometers, and 1 time of 25 to 30 kilometers of LSD, if the volume is not enough, run 4 times.

If you run 300-400 kilometers a month, you must run 4-5 times a week, otherwise it will be difficult to achieve this goal; if it exceeds 400 kilometers, it goes without saying that you must run 5-6 times a week (almost every day).

In addition, when the frequency and volume of running increase, you must warm up before running and stretch after running, otherwise it will increase the chance of injury. Common symptoms include stitches, muscle strains, knee pain, etc.

Some people run to lose weight. If you want to lose weight by running, you must first persist in running, and secondly, you also need to control the amount of running.

If you are overweight and have no previous exercise experience, in order to avoid the risk of knee injuries, it is recommended not to lose weight by running right away, because the probability of knee injuries is very high. It is recommended to proceed step by step, you can start with brisk walking to burn body fat, and wait until the body is fully stretched and adapted, and then do relatively intense jogging if you want to further improve your basal metabolism.

Keep brisk walking or jogging for more than 30 minutes each time, because aerobic exercise can burn fat, and running is a kind of aerobic exercise. It is generally recommended to do it 3 to 5 times a week. There is enough time for the body to rest, and there is enough time to ensure the amount of fat consumed (this is a recommended amount. Remember that a health cross-sectional study showed that maintaining a certain amount of fitness every week is good for the body).

2. Correct gait. Many running tutorials mention that running posture is critical. Correct gait helps reduce the impact from the ground and protect the knee joints to the greatest extent. We can see the correct running posture from the picture below: running steadily, fully pushing back, the center of gravity of the human body can move forward in a straight line, and the ups and downs and left and right swings of the center of gravity are minimized. All parts of the body, especially the head and upper and lower limbs, should be coordinated during running.

Figure 5, Schematic diagram of running posture

Ryan Hall, known as the Marathon Prince, has also made a series of videos to popularize science.

Some experts have summarized the key points

What is the correct jogging posture?

1. Move your body forward and keep it straight (do not lean forward or fall backward) 2. Let your toes land naturally, and relax in every movement 3. Lower your arms and swing them forward, stretch your arms and shoulders backward to open your chest and make breathing smooth 4. Keep your hips directly under your body (feel your hips rolling under your body when running) 5. Keep your head forward and directly above your shoulders, not to the left or right

3. A pair of suitable running shoes. When running, each impact will bear 1.2 to 1.5 times of your own weight. If you run 5 kilometers, you will hit the ground 4000-6000 times. You can imagine the load on your body. Therefore, a pair of suitable running shoes is of great significance to the protection of the knees.

The core part of running shoes is the shock-absorbing part, which requires two aspects: it can bear the weight of the human body and the impact of the ground, and it must maintain a certain rebound when the foot leaves the ground. In addition, the friction provided by the sole and the fixed ventilation of the upper are also issues that need to be considered.

Figure 6, schematic diagram of the running shoe structure

Therefore, it is recommended that you buy professional running shoes and you can choose according to your needs.

03. Reasonable nutritional supplementation

A large number of studies have shown that during exercise, the body's energy consumption is much greater than when it is at rest. Exercise leads to enhanced metabolism. For example, when a person is exercising at a moderate intensity, their energy consumption can reach 15-30% of their total daily consumption, while professional athletes can consume an average of 3500-4400Kcal per day, and some events may even exceed 5500Kcal.

Figure 7 Energy consumption during exercise

Under this rapid consumption, if the human body does not replenish the corresponding energy in time, many problems will arise.

Therefore, sports medicine or professional sports organizations generally provide athletes with corresponding nutritional supplements. Common supplements are divided into two categories: basic nutritional supplements and sports nutritional supplements.

1. Basic nutritional supplementation. Basic nutritional supplementation is to supplement the basic nutrients that are quickly consumed during exercise according to the body's metabolism. The basic nutrients in the human body include carbohydrates, lipids, and proteins .

Carbohydrates are the main energy source for the human body . 60% of the energy of the human body is directly supplied by carbohydrates. During exercise, carbohydrate consumption is also the largest, so it is very important to replenish carbohydrates after exercise. Generally, glycogen is significantly reduced after exercise, so it is necessary to replenish carbohydrates in time to restore blood sugar to normal, to prevent the decline of exercise ability due to low blood sugar, and even cause fainting.

Figure 8 Common sugars, terrible biochemistry

Protein is the basic substance of life , accounting for about 18% of the body weight. It is not only the basic structural component of the body's cell structure and the basic bearer of life activities, but also plays a role in regulating the body's physiological functions and serving as an important component of the human immune system. In addition, the oxygen transport on which we depend for survival depends on protein, various nutrients need protein to enter cells, and some hormones themselves are also proteins.

Figure 9 The role of protein

Therefore, it is very important to supplement protein after exercise.

Vitamins are important components of the human body . They are key to the human enzyme system and are important for regulating the normal functioning of the human body and maintaining metabolism. For example,

Vitamin B1 plays an important role in the production of ATP, the body's energy currency;

Vitamin B2 is related to human cell respiration and is very beneficial for aerobic exercise;

Vitamin C is a strong antioxidant that can eliminate free radical components that are harmful to the human body;

Vitamin D3 is of great significance in regulating the calcium and phosphorus metabolism of osteoblasts and can accelerate the formation of bone matrix.

Of course, vitamin supplementation is also a common practice for people who sit for a long time. Therefore, proper vitamin supplementation after exercise is conducive to eliminating fatigue and improving recovery speed.

2. Sports nutrition supplements. We call those that are combined with basic sports nutrition sports nutrition supplements (the usage of the State Sports General Administration), and some people also call them sports nutrition supplements or sports functional foods.

This category mainly plays an auxiliary role. Despite this, they are essential for exercise. For example, strength training generally requires improving muscle strength, so it is necessary to supplement protein, amino acids and creatine; the process of a large amount of exercise training requires improving the body's metabolic load and improving immunity, such as phospholipids or coenzyme Q. Because exercise itself puts a lot of pressure on the joints and may even cause joint wear or joint damage, it is generally necessary to supplement glucosamine, chondroitin, hyaluronic acid (joint fluid) and other substances.

Protein and creatine are commonly supplemented through protein powder and foods with high protein content. Protein powder is generally obtained by processing natural raw materials, such as protein from animal or plant sources, to meet the common essential amino acid supplements of the human body. How much protein powder should be consumed every day? Generally, the general public needs to consume 0.8 grams to 1.0 grams of protein per kilogram of body weight. For example, people weighing 60 kilograms need to consume about 60 grams. For people who exercise and keep fit, the number can be expanded to 1.5~2.0 grams.

Of course, most people supplement protein mainly through food, such as eating meat with high protein content (those who do fitness or like to supplement protein can learn about it. In fact, the three are similar, it’s just a foreign preference)

Figure 10 Nutritional composition of common meats

Generally speaking, all three of the above mentioned can be used as sports supplements. Since most domestic fitness theories come from abroad, people prefer beef. In fact, lean pork or chicken breast can achieve better results both in terms of nutritional content and actual effects.

3. Joint agents: glucosamine and chondroitin. Glucosamine is a basic component of cartilage and plays a key role in the formation of joint cartilage. Exogenous intake of glucosamine can stimulate the synthesis of proteoglycans in chondrocytes to replenish the loss of cartilage itself, thereby repairing cartilage. On the other hand, it can also inhibit inflammation in the body, reduce cartilage damage, and relieve pain caused by joint wear.

Figure 11 The therapeutic effect of glucosamine on joint damage

Chondroitin (CS) is an important component of connective tissue and can repair and protect cartilage.

Repair cartilage: CS promotes the formation of cartilage tissue by stimulating chondrocytes to synthesize hyaluronic acid (HA), PG and collagen.

Protect cartilage: CS has obvious affinity for cartilage and can preferentially enter cartilage tissue to protect cartilage:

• CS can inhibit the production of proteolytic and lysosomal enzymes, such as elastase, acetyl glucosaminidase, and other enzymes that damage articular cartilage.

• CS can enhance the ability of the synovium to produce hyaluronic acid (HA). Normal HA levels in the joint cavity can reduce the degeneration of the cartilage surface and alleviate the symptoms of osteoarthritis patients.

Hyaluronic acid (HA) is a component of the human body, generally distributed in articular cartilage and synovial fluid. It is a non-sulfated mucopolysaccharide that has lubricating and supporting effects. Since the second half of the last century, hyaluronic acid has become one of the important means of treating osteoarthritis.

In addition, other things such as coenzyme Q vary from person to person and need to be supplemented according to needs.

Once you have a certain understanding of the basic knowledge of running, and then start running, you can protect yourself to the greatest extent while exercising.

References

1. Sports joint stress Miller R H. Joint Loading in Runners Does Not Initiate Knee Osteoarthritis[J]. Exercise and sport sciences reviews, 2017,45(2): 87-95.

2. Walking and running pressure Stephenson J, Zesiewicz T, Gooch C, et al. Gait and balance in adults with Friedreich's ataxia[J]. Gait & posture, 2015,41(2): 603-607.

3. Huang Xiang. Observation and analysis of incorrect “running posture” that affects students’ speed quality. Track and Field. 2012, 4

4. Wang Jinliang, Peng Yunzhi. Discussion on sports nutrition supplement. Journal of Xiangtan Normal University (Natural Science Edition) 2006, 28(4)

5. He Liqun, Xu Qi. Research trends of sports nutrition supplements. Journal of Beijing Sport University, 2011, 34(3)

6. Research on glucosamine for arthritis. Dai Lie. Current status of glucosamine in the treatment of osteoarthritis[J]. Chinese Journal of New Drugs and Clinical Practice, 2004, 7.

7. Chen Lei, et al. Role of chondroitin sulfate in the prevention and treatment of osteoarthritis. Chinese Journal of Biochemical Pharmacology. 2008, 29(2): 137-139

8. Fang Zhong, Li Feng, Xiong Wei, et al. Observation on the efficacy of Glucosamine combined with intra-articular injection of sodium hyaluronate in the treatment of knee osteoarthritis [J]. Chinese Journal of Gerontology, 2006, 26(7): 871.