One twin only does hammer curls. The other twin only does preacher's biceps curls. Will it make a difference for how their arms look? - Quora
What are the benefits of hammer curls? - Quora
The hammer curl is the perfect all-around arm builder. It hits the biceps, brachialis and brachioradialis muscles, helping you a… | Muscle fitness, Workout, Fitness
Cross body hammer curls - Biceps/ Brachialis - YouTube
Hammer Curl The hammer curl is a get arm exercise that that focuses on the bicep brachii, brachialis and extensor mu… | Bodybuilding workouts, Exercise, Arm workout
Dumbbell hammer curl to dumbbell reverse curl exercise