When running, every step you take subjects your knees to seven times your body weight in pressure, your quadriceps to four times, and your feet to three times. Medical experts point out that during normal forward motion, the kneecap and femur have the largest contact surface, allowing the force to be distributed evenly. However, if your posture is incorrect—especially if you take large strides in an attempt to run faster—it can increase joint stress, even causing the patella to tilt outward or rotate inward, accelerating wear on the cartilage of the contact surface. This not only affects your future running but can even make walking and climbing stairs difficult.

Incorrect posture: 1. Leaning backward makes forward strides 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 bear the load, indirectly increasing knee pressure; 3. Taking large strides moves your center of gravity farther from your supporting foot, requiring the quadriceps to work harder to maintain balance and increasing the strain on the patellofemoral joint.

Correct posture: 1. Leaning slightly forward helps propel you forward and reduces effort; 2. Bending the knees allows the thigh muscles to engage, distributing pressure and acting as a shock absorber, while also increasing the contact area between the patella and femur to better distribute pressure and reduce friction; 3. Taking smaller, quicker steps keeps your center of gravity closer to your supporting foot, requiring less effort from the quadriceps to maintain balance and reducing the strain on the patellofemoral joint.