Question Re: Resistance Band Strength

ZugTheMegasaurus

Had a question on resistance bands and even my strongest Google-Fu is not yielding a definitive result, so thought I'd see if anyone here had a good answer or source.

I have a set of Bodylastics resistance bands that I use for strength training. They're each labeled with the strength of the band, 5 lbs to 30 lbs, and you can combine them to get a wide variety of weights. I've been very pleased with them. My boyfriend uses a pair of 60 lb dumbbells, but wanted to start using the bands to work muscles he felt he was neglecting. I showed him how to use them one morning before I left for school. When I got home, he told me that he could barely budge 60 lbs worth of the bands and when he looked it up, discovered that doubling the band over like I showed him actually doubles the resistance of the band (so he was actually attempting 120 lbs).

Now, that makes some sense, but it seems like every source I can find is just someone's blog and I don't know if it's true. It's not a big deal if no one knows, but I'm interested to find out just because that means I'm a hell of a lot stronger than I've been giving myself credit for. Does anyone know whether this does double the resistance/weight, increases it to some lesser degree, or nothing at all, or can anyone point me in the right direction?

ZugTheMegasaurus

Bumping in the hope someone sees!

Aerohead21

What do you mean by doubling over? If you are using them the traditional way, that would be whatever poundage each side, but if you fold it in half and then use it, that would double the weight for each side.

ZugTheMegasaurus

What do you mean by doubling over? If you are using them the traditional way, that would be whatever poundage each side, but if you fold it in half and then use it, that would double the weight for each side.

Basically attaching both ends of the band to a single handle, and stepping on the middle to hold it down (for bicep curls, for example).

Papillon22

I don't have an answer to your question, but I find this very intriguing! I love my little bands and I never thought of doubling them up!
I hope someone can answer this question.

Aerohead21

If you use one arm to curl, then yes - you'd be doubling the weight.

ZugTheMegasaurus

If you use one arm to curl, then yes - you'd be doubling the weight.

It seems so obvious when you say it, haha. I don't know why it's not working out in my head; I guess it's been too long since I've brushed up on my physics! Well, that and the fact that I apparently am doing double what I thought I was. In a bit of shock over that, to be honest!

Aerohead21

NSV!!! Wooohooo!!!!!!!!

jonchew

Hmmm, my intuition says that you'd be more than doubling, especially if you are stretching the bands a considerable distance. The bands only stretch so-far, before you extend beyond their normal usage limit, and meet greater resistance.

I have a feeling that you'd have a different feel, by stretching 2-30lb bands, as opposed to (over)stretching 1-doubled 30lb band.

Absolutely no scientific proof here to base this on... just a feeling.

michaelschultz12979

Elastic band systems allow for multiple bands for increased resistance. When you fold the elastic under your foot or ring, or anything else you are, in effect, adding another elastic. Two elastics are being pulled from an anchor spot. If both ends are being pulled by the same muscles, the force is 2x. If each end is being pulled by different muscles then the force is 1x for each set of muscles.

The length of the stretch under tension produces force, but the length of the relaxed cord does not.

A band stretches according to Hooks Law F=kx. x is the distance stretched, and k is a constant for the material being stretched.

For two bands of the same material Hooks Law says: F= kx + kx

When using multiple bands the equation would look like F = k1x + k2x + k3x + ........where k1, k2, k3, .... are the elastic constants of each particular band.

BTW, I don't think overstretching is a good idea as violating Hooks law is not possible. (Physics here) What happens is you deform the material, changing the constant. Deforming the material changes that constant throughout it's tension. Consider what happens when you pull a spring further than it is made to stretch. The bands will weaken and prematurely fail.