Calculating Leverage & Force in Lower Leg Squat

  • Context: High School 
  • Thread starter Thread starter tomlib
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Discussion Overview

The discussion revolves around calculating the leverage on the lower leg during a squat and determining the force that the thigh muscle must exert for the body to perform the squat. It includes theoretical considerations and practical applications related to biomechanics and physics of movement.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant requests assistance in calculating leverage and force during a squat.
  • Another participant suggests looking up the effective lever arm of the quadriceps at different knee flexion angles, noting that it varies based on patella anatomy and is roughly around 5 cm.
  • A third participant mentions that external torque can be computed from the ground reaction force using inverse dynamics or from knee position alone.
  • One participant expresses a preference for using classic force distribution by vectors and trigonometry rather than torque calculations, indicating a lack of understanding of the concepts involved.
  • Another participant questions the realism of the squat movement in the context of the discussed models, comparing it to the effort required in windsurfing.

Areas of Agreement / Disagreement

Participants express differing views on the methods for calculating forces and leverage, with some favoring torque calculations and others preferring vector analysis. The discussion remains unresolved regarding the most appropriate approach to take.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about anatomy and the specific conditions under which the calculations are applied. The varying interpretations of the squat movement and its feasibility also contribute to the complexity of the discussion.

tomlib
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How can I calculate the leverage on the lower leg during a squat and the force that the thigh muscle must exert in order for the body to perform the squat. Can you help me?
 
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tomlib said:
How can I calculate the leverage on the lower leg during a squat and the force that the thigh muscle must exert in order for the body to perform the squat. Can you help me?
You have to look up the effective lever arm of the quadriceps at different knee flexion angles. It varies based on patella anatomy, but is roughly around 5 cm. The external torque can be computed from the ground reaction force, by inverse dynamics (if you care about the shank and foot mass), or just from the knee position.
 
I would not count the torque, I would like to stick to the classic distribution of forces by vectors using trigonometry and crank calculation. Unfortunately, I don't have such an opportunity to understand everything. This movement seems unrealistic to me.

I saw how much work it can be to raise a sail for windsurfing.
When applying this model, the rope is actually in line with the boom, such a force is impossible.
 
tomlib said:
This movement seems unrealistic to me.
A simple squat?
 

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