Muscles have the lowest potential to generate force when they're either fully elongated (stretched) or fully shortened (contracted). They generate the highest possible tension in the middle – halfway through the range of motion. Another reason to focus on the mid-range is because it's the position where maximal loading of the biceps occurs.

We can use that info to make the classic 21's method for biceps even better. Try this:

  • 7 Leaning Biceps Curls
  • 7-Second Isometric Mid-Range Hold with Wrist Pronation/Supination
  • 7 Full Range of Motion Reps

Perform this protocol using two sets of dumbbells. Begin with the lighter set and perform the first exercise, then switch to a pair that's 5 pounds heavier and perform the other two exercises. For example, start with 20-pound dumbbells, then switch to 25-pound dumbbells.

Related:  Advanced 21s for Hypertrophy

Related:  6 Biceps Exercises You Should Be Doing