For your biceps, the key is variety.
Trying grabbing a bar and doing curls only half way up (so your upper arm & forearm create a 90 degree angle). Do this 7 times. Immediately after that do 7 more going all the way up but not don't bring it down past 90 degrees. After that do 7 full bicep curls.
So it should be like this, 7 lower half curls, 7 upper half curls, then 7 full curls. That is ONE set. Be sure you don't use weight that is too heavy for you to complete one set.
When you do curls with bars, try putting your hands at different widths because you want to work the outside part and inside part of the biceps. Experiment!
Also do hammer curls. Grab dumbbells and do curls where you don't twist your wrists. The motion is similiar to hammering something with a hammer. This exercise works out a part of the biceps that is often ignored by many other bicep exercises.
Also, try laying on an incline bench and doing curls with dumbbells. This is great because you can't rock your body to help you with the curls and there's a bigger range of motion for your arms.
Hope these all made sense!
- The Gracie Hunter
- The Prodigy