Physics of Fitness Fridays - You Don't Know Squat!

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You don’t know squat! Today I’m going to discuss the basic principles behind a front-loaded squat and a back-loaded squat.

When you squat, you are basically lifting the weight of your upper body (torso, head, arms) plus whatever weight you wish to add on. We’ll assume your legs are massless for this exercise. (I know that they can feel like lead, but bear with me.)

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You need to balance this weight over your feet, or else you’ll tip over (not recommended)!

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To lift the weight, you use (primarily) your glutes and quads. Those muscles act around your hip and knee joints respectively as levers.

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The weight creates torques at each of these joints. Torque is a force applied around a pivot point (ie, the joint) and is defined as T = r x F, where r is the torque arm and F is the force, or in this case, weight.

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There are two joints and therefore two torques and two torque arms. The cross product means that the torque arm is the perpendicular distance from the force to the joint, denoted by the yellow dotted lines.

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Now compare a front and a back loaded squat. Your torso shifts to adjust for the weight and to stay balanced over the feet.

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Thus, the torque arms shift accordingly. For a back loaded squat, the torque arm for the hips increases relative to the front squat.

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So, a front squat places more torque on the knees, while a back squat places more torque on the hips!

If you’d like to read more, check out: https://squatuniversity.com/2016/04/20/the-real-science-of-the-squat/

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