The chin-up… everybody hates them. But it's one of the best exercise you can do to improve arm strength. Men's Health shows you the correct way to do a "chin up" in this exercise video. When performing a chin-up, keeping a slight bend maintains tension in your biceps.
Grab a chin-up bar with an underhand grip, palms facing towards you, your hands about shoulder width apart. Pull yourself up until the bar is below your chin. Squeeze your biceps at the top.
Now, slowly lower yourself until your arms are almost straight. Keeping a slight bend maintains tension in your biceps, although your back and forearms will be also be working hard to help lift you up and down.
If you find yourself swinging, just touch your toes slightly onto the ground at the end of each rep. This will help stabilize you as you work towards finishing your set. Breathe out as you lift up and breathe in again as you descend towards the floor.