During heel strike, what moment is the knee experiencing and how is it being countered?

During heel strike, the knee experiences a flexion moment due to the body's weight transferring onto the leg that has just made contact with the ground. This moment of flexion is primarily countered by the quadriceps muscles through an eccentric contraction. Eccentric contractions occur when a muscle lengthens while producing force, which in the case of the quadriceps, helps to control the degree of knee flexion as the body's weight continues to come down.

The quadriceps are crucial at heel strike for stabilizing the knee and preventing it from excessively flexing under the load of the body's weight, thus promoting efficient and controlled movement. This is particularly important in activities like walking or running, where the knee must maintain an appropriate position to ensure optimal function and to prevent injury.

In summary, the knee experiences a flexion moment during heel strike, and it is effectively managed by the quadriceps performing eccentric contractions, maintaining stability and control as the body transitions through the gait cycle.