The bicep curl is the standard arm exercise and the best-known isolation movement there is. Proper execution and a full range of motion are what drive growth.
Technique
1Keep your elbows pinned to your sides — they should not drift forward
2Supinate your wrist (rotate your hand outward) on the way up with dumbbells
3Lower all the way for a full stretch — do not cut the rep short
4Do not use your body to swing the weight up
5Squeeze the biceps hard at the top and lower slowly (2–3 sec)