Generally, biceps exercises are set up so the upper arms remain roughly parallel to the torso and the resistance reduces as the hands get closer to the chest. But the guillotine curl requires the upper arms to be positioned perpendicular to the torso with the shoulders flexed (arms forward with respect to the torso). That makes the resistance grow stronger – instead of decreasing – as the cable moves downward toward the body.
This is a great finisher exercise when training biceps. Hold and squeeze the biceps at the peak contraction to further heighten the training effect.
One of the ironies of bodybuilding is that the more some people work out, the worse they look. Whatever happened to grace, elegance, esthetics, and functionality?
One of my favorite books is A Book Of Five Rings by Miyomato Musashi. Musashi was a badass 17th century Japanese swordsman who never lost a duel in over sixty fights. This book outlines his philosophy of success. I re-read it recently and was amazed by how many of his principles apply to a variety of areas in life, including productive strength training.