21s Bicep Curls
1. Start with dumbbells in a lowered position, palms facing out.
2. Do 7 lower-half reps: curl half way up so that your forearms are parallel with the ground
3. Do 7 upper-half reps: start with your elbows half flexed so that your forearms are parallel with the ground and curl the dumbbell until your elbow is fully flexed. Extend your elbow back to the half up point
4. Do 7 full reps: start with the dumbbells in a completely lowered position and curl all the way to the top
The total is 21 reps, hence the name!