Bike Fit and Knee Pain
One of the biggest problems I see with cyclists and athletes that have had a history of knee injury is the quad dominant strategy. When it comes to cycling or any kind of propulsive movement, there are three main groups of muscles that we are discussing – the quadriceps, hamstrings and gluteals
-The quadriceps, as the name suggests, consists of 4 muscles that are primarily responsible for extending or straightening the knee and keeps that patella (knee cap) stabilized in the groove of the femur -The hamstrings flex the knee and also act as secondary extensors of the hip. They play a role in stabilizing the pelvis to transfer load -The gluteals are the primary extensors of the hip and extend the leg backwards. They are the “power” muscles of the hip to extend, externally rotate and abduct the hip. Our bodies tend to like balance and synergy. If any groups of these muscles are “overly dominant” then problems are likely to arise. For cyclists and runners, the dreaded patellofemoral pain term tends to pop up quite a bit. The patellofemoral joint is where the patella (knee cap) fits into the articulating surface of the femur (thigh bone). The patella fits loosely into the groove of the femur and its primary muscular attachment is the quadriceps muscle.
The patellofemoral joint is exposed to high stresses during athletic activity. As the knee flexes or bends, greater components of the quadriceps forces compression of the patella against the groove of the femur. Just to put it into perspective, walking can produce patellofemoral compressive forces of 50% of body weight, while running has been estimated at 5 times body weight. Getting up from a chair has been estimated at nearly 7 times body weight.
When the knee is stressed with so much force and there is no balance of the posterior muscles of the leg, you can see why the added stress can have such an impact. One of the most important movements that I take a look at during bike fits and physical therapy evaluations is the squat. A good squatting motion proves to me that the client is able to find balance between the quads, glutes, and hamstrings without being overly reliant on one muscle group. When this squat pattern is broken, then it’s a clear sign that the body is not coordinating movements properly. Since cycling is such a quad dominant activity, the gluteals and hamstrings ar