Butterfly vs fly?

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CaseLogic
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Butterfly vs fly?

Post by CaseLogic » Mon Dec 07, 2009 10:54 am

We have both a fly and a butterfly machine. The movement is very similar but the hand/arm placement is different. With butterfly you have your forearms vertical with your arms at a 90 degree angle as you bring the weight in. With fly you just use your arm and rotate in.

What is the difference in terms of muscle usage?

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Stephen Johnson
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Re: Butterfly vs fly?

Post by Stephen Johnson » Mon Dec 07, 2009 11:35 am

CaseLogic wrote:We have both a fly and a butterfly machine. The movement is very similar but the hand/arm placement is different. With butterfly you have your forearms vertical with your arms at a 90 degree angle as you bring the weight in. With fly you just use your arm and rotate in.

What is the difference in terms of muscle usage?
The fly involves the transverse flexion articulation of the shoulder joint. The butterfly uses the transverse adduction articulation. The two links show the muscle usage of each articulation, but in short, transverse flexion involves the anterior deltoid and biceps while transverse adduction doesn't. Both target the pectorals, however. Because a bent arm is a shorter lever than a fully extended arm, you can use more weight with the butterfly than the fly.

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