The triceps make up two-thirds of the mass of your upper arm. If the tape measure isn’t moving like you hoped, make sure you aren’t neglecting them. The term triceps means three heads: the medial, the lateral, and the long head. The long head’s origin is on the scapula, or shoulder blade. The origins of the medial and lateral heads are on the humerus. The origin of the long head allows you to stretch it by raising your arm above your head. The medial and lateral heads do not stretch as you raise your arm because they aren’t connected to the scapula. To place more emphasis on the long head, use movements with arms extended or above the head. To place more emphasis on the medial and lateral heads, use movements with the arms down and close-grip pressing movements.

OVERHEAD EXTENSIONS STRESS THE TRICEPS LONG HEAD TO A GREATER DEGREE THAN THE OTHER TWO HEADS.

 TRIPLE-ASSAULT TRICEPS WORKOUT 

Rope Pushdown: 3 sets, 12–15 reps

Lying Extension: 3 sets, 10–15 reps

One-arm Overhead Extension: 3 sets, 12–15 reps