Tension can be a good thing—that is, when your girlfriend or your job aren’t the cause of it. The next time you train arms, do dumbbell preacher curls with a “crush grip”—squeeze the ends of the dumbbells together through- out each rep. Try to crush the weights between your hands. Sometimes referred to as “irradiation,” the tension the crushing motion creates engages and coordinates more muscle fibers. It activates your shoulders, chest, and upper back, which stabilize the movement.
As a result, you can handle a heavier weight while still maintaining a strict biceps curl. Start your sets with a weight that’s 50%–60% of the heaviest load you could do for 10–12 reps, just to get used to the feeling, and then gradually increase the load. To make the exercise even more advanced, hold the handles toward the outside ends.
Important: Don't allow a gap at the top or bottom; keep the weights pressed firmly together throughout the entire movement.
Quick Tips: You can also use the crush grip on other curl variations like hammer curls and spider curls (hang over the edge of a preacher bench so your arms are supported but vertical).