1. Free Weight Arm Curl vs Arm Curl with Pulley

Hey guys,

Im just curious about the difference in resistance between a short barbell arm/bicep curl and a arm curl using a pulley (the one where you can also change the height)

I could do 70lbs on the free weight and feel a good pump but for some reason i can do 145lbs with the one on the pulley same reps and sets.

So i wanted to know if anyone knew the formula to calculate the difference in resistance between weights.

For example Leg Curl vs Squat resistance is (lbs x sin 45deg)

thanks for the input

2. I believe it depends on the number of pulleys. They considerably reduce the effort required to move the weight.
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3. yeah thats true.

I looked it up online and it seems that half the force is needed to pull a weight that is being pulled by gravity.

so if i was doing 145 that would be in free weight i was really doing about 72.5 which "feels" about right to me.

4. The thing I love about the stacks is the constant resistance. When you're curling a bar/dumbells, about 2/3 of the way up, you lose most of the gravity resistance, because you're mostly moving the weight parallel to the ground, instead of perpendicular. With the pulley stacks, you get constant resistance all the way through the movement, to full contraction. I curl almost exclusively with the pulleys nowadays.

5. Definitely man, i think I'm going with the pulley stacks much more now. The feeling with the stack for me is not only constant resistance but also much more controlled pumps.

I'm not sure if my formula is correct but i think i can assume that the weight on the stack divided by 2 is the real resistance.
Half the tension goes on the rope; the length of the rope is also a factor but i think I'm close!
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