Cable Curls: Elastic Straps on Pulleys Increase Exercise Intensity

Scientists from the Laboratory of Physiology, European University Miguel de Cervantes in Spain (Garcia-Lopez. 2010) studied the effect of elastic straps (instead of the standard cables) attached to a cable pulley on the intensity and mechanics of cable curls. While they did not measure muscle stimulation via EMG, their conclusion that the increasing resistance that resulted from modification of the pulley would lead to a greater activition of the target muscle appears sensible:

With a more uniformly distributed external resistance, a greater average muscle tension could have been achieved throughout the range of movement, leading to greater fatigue that could explain the lower number of maximal repetitions achieved.

If we remind ourselves of the bro-scientific wisdom that concentration curls, which are characterized by maximal torque at full contraction, is the way to go for cannon-ball biceps development, the use of elastic straps on cable pulleys could well improve your biceps peaks.