Women’s wider hips compared to men create a more pronounced angle between the pelvis and the knee (called the quadriceps-angle or Q-angle), as the femur occurs at a more oblique angle compared to the femur of a man. A large Q-angle causes the patella to be more off-center from the tibia, which affects the alignment of the legs in the frontal plane. Tracking of the patella against the femur is dependent on direction of the force produced by the quadriceps. With a wide Q-angle, there is more lateral movement of the patella as the quadriceps contract, which can potentially put female runners at a greater risk for knee injuries (e.g., patellofemoral pain syndrome) than male runners. Research has shown that, although many females who have knee pain tend to have larger Q-angles, some studies have shown that there is no relationship between Q-angle and the development of knee pain, which suggests that factors other than or in addition to Q-angle (e.g., weak hip abductor muscles) contribute to the development of knee injuries. It seems that Q-angle is at least partially responsible for knee injury risk among female runners since a large Q-angle can influence a female runner’s knee joint biomechanics upon foot strike with the ground, especially when weak hip abductor muscles are unable to compensate to create greater stability upon landing.
A larger Q-angle also puts women at a mechanical disadvantage when running. After a woman’s leg lands on the ground, she must push off the ground to propel herself forward. The application of muscular force has both a magnitude and direction. And the direction the force is applied has both a horizontal and vertical component. The more parallel a runner’s leg is to her body when it’s on the ground (i.e., the smaller the Q-angle), the greater the amount of the applied muscle force is transmitted in the vertical direction to the tendons to move the bones.
With wide hips and a large Q-angle, the femur is at an angle when the leg is on the ground. Thus, there is a greater dispersion of force in different directions, with some of the force of the muscles surrounding the femur (quadriceps in the front and hamstrings in the back) being lost in the horizontal direction rather than being transmitted into propelling the runner forward. If you watch elite female runners, you’ll notice they have very narrow hips that more closely resemble male runners. Research has shown that the hip width of very good female runners is similar to that of both athletic and even non-athletic males. Narrow hips allow runners to direct more of the muscular force into forward propulsion.
