To maximize your arm muscles, the "standing barbell curl" is the perfect exercise. To better maximize your muscles, keep tension on the arms throughout the move. This triceps muscle exercise from Men's Health is great for any man looking to get in shape.
Stand holding a bar-bell in front of your thighs with an underhand grip, your hands shoulder-width apart. Keeping your back straight and your elbows at your sides, slowly curl the bar up in a semi-circular motion until your forearms touch your biceps.
Pause then slowly lower the bar to about an inch in front of your thighs before repeating the move. This simple bicep exercise is almost always performed badly. Do not swing or jerk the bar up but instead aim to keep tension on the arms throughout the move.
Try standing with your back against a wall to help prevent yourself from cheating on this exercise. Try not to let your elbows drift forward as this puts stress on the shoulder instead of the target muscles – the biceps.