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Diagram:

A - Resistance machine configured with 50lbs of resistance and in an overhead pulley system

B - Performing a bicep exercise standing with feet shoulder width apart and underneath torso

C - Performing a bicep exercise standing with feet shoulder width apart with lead foot slight forward of torso and bracing rear foot slightly back with knees slightly bent

Observed results:

Without bracing one leg behind me, I'm pulled backwards and unable to complete the exercise. When applying a brace leg in the rear, I'm able to complete the exercise.

My question is, assuming the only joint that moves during exercise is the elbow on the arm doing the work, does the exercise become less effective by bracing the body from falling over? Does the act of implementing a brace, effectively reduce the weight and amount of work that the arm muscle does?

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The brace does not move and does no work. The work done is determined by the weight being lifted.

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  • $\begingroup$ I guess my struggle here is, what is the mechanical function of the brace if it's not making lifting the load easier. Is it just lowering the center of gravity? $\endgroup$ Commented Jun 12, 2020 at 14:12
  • $\begingroup$ The brace contributes a torque to counter the one from the rope' $\endgroup$
    – R.W. Bird
    Commented Jun 12, 2020 at 15:20

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