How does using these elastic bands compare to using free weights?
Your muscle don’t know the difference between free weights and elastic bands and weight lifting machines. It only knows the resistance it’s working against. The source of the resistance is irrelevant to the body’s muscles. So that point being equal, what other criteria distinguish one from the other? Cost, portability, safety: in all of these areas, Bodylastic bands have an edge over the others. Additionally, the more you stretch Bodylastsic bands, the more difficult they get to stretch, which has the added benefit of placing additional stress on your muscles at just the right time for it to have the greatest effect.
