As the weight on a barbell increases during a squat, computer simulations show that the torso leans forward more and the hips take on more of the workload than the knees, suggesting that the maximum...
Mechanism
Synthesis from 1 study
When you squat with heavier weights, your knees can’t handle as much force as your hips, so your body leans forward more to let your hips do more of the work. This isn’t a choice — it’s how your bones and muscles naturally adjust to stay within their physical limits.
Most probable mechanism
When you lift heavier weights, your hips and knees can only generate so much force before they hit their physical limits — so your body leans forward more to let your hips take more of the load, because they can handle it better than your knees at those high forces.
Increasing external load raises the required joint moments at the hip and knee to maintain balance and lift the weight.
The knee joint reaches its mechanical limit for torque production earlier than the hip joint under high loads due to anatomical and muscular constraints.
To avoid exceeding the knee’s torque capacity, the body repositions the torso into a more inclined angle, increasing the lever arm of the hip extensors and reducing the lever arm of the knee extensors.
This postural shift redirects a greater proportion of the total mechanical demand from the knee to the hip joint, allowing movement to continue within the biomechanical limits of both joints.
Evidence from Studies
Supporting (1)
Community contributions welcome
Numerical Modeling of Load-Driven Changes in Squat Technique Using a Moment-Limited Joint Framework
Contradicting (0)
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