Stair climbing increases the knee joint burden Let’s first look at what the action of stair climbing actually does to our knee joint. If a person weighing 60 kg bends his knees close to 90° when climbing stairs, the line of force of the body’s center of gravity is about 20 cm from the center of the knee joint, and the line of force generated by the quadriceps through the patella is about 6 cm from the center of the knee joint, so even a junior high school student can easily calculate that in order to climb these stairs, the quadriceps need to generate almost 200 kg of tension –We have omitted the mass to force conversion for the sake of simplicity and ease of understanding. In fact, this is not even the pressure between the meniscus and the tibial plateau and the femoral condyles. If we take into account the reaction force of the ground, that is, the support force of the ground on the person, the above pressure will reach 280 kg. In addition, the pulling force of the quadriceps muscle during stairs, which changes the direction of the force through the patella, will press the patella against the patellofemoral joint surface, which will also generate a pressure of about 280 kg on the patellofemoral joint surface. In short, every time we go up a flight of stairs, the cartilage surface of our knee joint is subjected to a pressure of more than 4 times our body weight. So, if we look at the mechanics alone, any stair climbing is a tremendous amount of pressure and wear on the patellofemoral and tibiofemoral cartilage surfaces. The articular cartilage surfaces are irreparable once damaged because they have no blood supply. Therefore, it is obvious in our daily life that people who used more physical labor and legs when they were younger are more prone to knee pain, earlier knee degeneration and osteoarthritis. It is no wonder that many orthopedic surgeons even say “never climb stairs if there is an elevator”. There are two sides to everything. Is there really no benefit to climbing stairs at all? Of course not. Although stair climbing is basically not good for the knee joint, it is good for cardio training. Stair climbing is generally considered to be a moderate intensity exercise that uses three times as much energy as walking at 4 kilometers per hour. Therefore, climbing stairs for more than 30 to 40 minutes (basically the same as climbing a mountain) is a very good cardio endurance exercise and is very good for improving cardiorespiratory fitness. In addition, because stair climbing is a very convenient exercise, we can combine exercise and daily work life, even if you can not continue to climb the stairs to exercise cardiorespiratory function, the number of stair climbing every day can be accumulated to burn enough energy, for those who wish to lose weight and diabetic patients, are good ways to exercise.