Interviewed Expert / Zheng Qiujian, Chief Physician of Orthopedics at Guangdong Provincial People's Hospital | Text / Xie Zhe, Reporter of Yangcheng Evening News | Correspondent Zhang Danna
Traditional weight loss methods are simple and can be summarized as "control your diet and stay active." As one of the simplest forms of exercise, running is often used for weight loss. In some weight loss experience sharing, high-intensity exercises such as stair climbing and hiking are also common. Experts say that while exercise helps with weight loss, choosing inappropriate activities can be very harmful to the knee joints.
Lose weight by running, but develop arthritis
Mr. Chen, 40, has maintained a weight of around 180 jin (approximately 90 kg) for years. Recently, as his "potbelly" became more prominent, he finally decided to lose weight. In his view, dieting is a method for girls, and as a man, he should definitely lose weight through exercise. So he chose the simplest form—running. He ran for an hour every evening and went hiking on weekends. After a month, while his weight had decreased somewhat, Mr. Chen began to feel pain in his knees, which grew increasingly severe. Even reducing his exercise didn’t help. After a hospital check-up, doctors told him he had developed osteoarthritis and advised him to stop exercising and seek treatment. This left Mr. Chen puzzled—aren’t weight loss and exercise supposed to be good for both body and mind? Why did they lead to arthritis?
Zheng Qiujian, Chief Physician of Orthopedics at Guangdong Provincial People's Hospital, explained that after the age of 30, the cartilage in human joints begins to naturally degenerate. Obesity and increased body weight obviously add more burden to the joints and accelerate the degeneration of cartilage. Studies have shown that among people of the same age group over 50, for every 10% decrease in body weight, the degree of cartilage degeneration decreases by 15%. "The transparent cartilage in joint areas is one of the most inert tissues in the human body, and its ability to repair is also the worst. Once damaged, it is difficult to recover, and this process is irreversible." In addition to natural aging, damage to transparent cartilage is mostly caused by mechanical injuries from improper exercise. Especially unsuitable or excessive exercise can worsen the wear of knee cartilage, leading to degenerative joint disease, resulting in symptoms such as bone and joint pain, swelling, and limited mobility.
Swimming, brisk walking, and other exercises are more suitable for weight loss
"There's no doubt that exercise benefits heart and lung function, and increasing muscle strength through appropriate exercise is also very important for maintaining joint stability," said Zheng Qiujian. Weight loss and exercise are both good things, but we must not overlook the fact that certain exercises such as running, hiking, and stair climbing can harm the knee joints. Especially for obese individuals, running for weight loss can be like adding insult to injury for the joints. "The normal range for Body Mass Index (BMI) is 18–24. When BMI generally exceeds 28, one should be cautious about choosing the type of exercise. Many people hope for quick results when losing weight, wishing to shed over ten jin (5 kg) in a month. As a result, those who aren’t used to exercising suddenly engage in intense workouts, expecting rapid weight loss, which often backfires. Experts warn that if obese individuals feel knee discomfort, or experience symptoms such as soreness or pain during running for weight loss, they should stop exercising immediately.
So how should one choose between exercising for weight loss and minimizing knee joint damage? Zheng Qiujian believes this is not a difficult decision. For weight loss through exercise, other aerobic activities can be chosen, such as brisk walking, swimming, and cycling, which are all excellent options. On one hand, they provide exercise benefits, and on the other, they cause less damage to the knee joints. It’s worth mentioning that even the best exercise can harm the body if done excessively. In fact, any exercise should be approached gradually, slowly increasing intensity to allow the body to adapt. Especially important is the warm-up before exercise. Many sports injuries occur because the body hasn’t yet adapted, and the joint capsules haven’t secreted enough lubricating fluid, making the joints vulnerable to damage.