With every step you take while running, your knees bear seven times your body weight in pressure, your quadriceps bear four times, and your soles bear three times. Associate Professor Yeung Sai-mo, from the Department of Rehabilitation Sciences at the Hong Kong Polytechnic University and Vice-Chairman of the Hong Kong Amateur Athletic Association, pointed out that during running, when the knee moves forward normally, the contact area between the patella and femur is the largest, allowing force to be evenly distributed. However, incorrect posture—especially taking long strides in pursuit of speed—can increase joint pressure, even causing the patella to tilt outward or rotate inward, accelerating the wear on the cartilage of the contact surface. This not only affects future running, but can also make walking and going up and down stairs difficult.
Incorrect posture (as shown on the left in the image above): 1. The body leans backward, making forward steps more strenuous; 2. Landing on the heel with the entire leg straight increases the impact on the knees and prevents the thigh muscles from helping to distribute weight, indirectly increasing knee pressure; 3. Taking large strides means the body’s center of gravity is farther from the supporting foot, requiring the quadriceps to use more force to maintain balance, thereby increasing the strain on the patellofemoral joint.
Correct posture (as shown on the right in the image above): 1. Leaning the body forward provides momentum and saves energy; 2. Bending the knees facilitates engaging the thigh muscles to help distribute pressure and act as a cushion, while also increasing the contact area of the patellofemoral joint to better distribute pressure and reduce friction; 3. Running with small, quick steps keeps the body’s center of gravity closer to the supporting foot, meaning the quadriceps don’t need to work as hard to maintain balance and the patellofemoral joint experiences less strain.