Tell me why it is said that people’s legs age first?

In real life, you can find that many people look quite young and in good physical condition when they get older, but they always have more or less leg problems. For example, the lower limbs are heavy, the knees are stiff, it is difficult to go up and down stairs, and eventually it becomes difficult to even walk. The reason why the elderly tremble slightly when walking and need to use crutches is because their legs and feet are not flexible. This is what we often call "people's legs age first." So why does "legs age first when people age"? The reason is that after the human body enters old age, various body organs will gradually age, and the bones and joints of the legs are the most used and loaded sports organs in people's daily lives. Decades of load-bearing and wear and tear cause greater damage than other organs, so aging appears earliest. Medically, this kind of aging of bones and joints due to natural wear and tear is called "bone and joint degeneration". This is also what people often call "senile legs". The originally flexible and coordinated legs have become clumsy and slow, and you may step on the air or trip down if you are not careful. The occurrence and development of "senile legs" are closely related to its causes, the most important of which is age. Medical surveys and studies have found that the incidence rate in people over 50 years old accounts for 25% to 30%, and the incidence rate in people over 60 years old accounts for 50% to 70%. Among them, the incidence rate in women is much higher than that in men, with a male to female ratio of 1:4. This is related to the decrease in estrogen levels and calcium and phosphorus imbalance in women after menopause, leading to bone metabolism disorders. Secondly, obesity and osteoporosis can also lead to "old legs." But it doesn’t mean that people will definitely get “senile legs” when they get old. The key lies in a reasonable diet and exercise. For example, women should pay attention to calcium supplements, especially after menopause, while men should also take calcium supplements after the age of 50. Eat more foods high in calcium and get plenty of sunshine. You should exercise moderately, such as walking slowly, and the intensity of your movements should not be too high, so as not to be more detrimental to the bones and joints. For example, it is recommended that some women who love beauty should pay special attention to keeping their legs warm in the cold winter, and not let their legs suffer from cold for a long time just for the sake of beauty. The cold will cause joint damage, and there will be more leg problems in old age.