I read a Frederic Delavier’s book « Strength Training Anatomy » and there is good stuff.
Lying on the bench, you take the barbell with a pronated grip with your arms in vertical :
Inhale and flex your arms. Taking care to not spread too much your elbows to go down the barbell at your forehead or behind your head.
Back to the start position and exhale at the end of the movement
- Barbell at your forehead level: Works mainly your medial head and lateral head of triceps muscle.
- Barbell behind your head: Works mainly your long head of triceps muscle.
To make this movement easier, you can use an overhead triceps machine. This allows for greater concentration on the triceps long head.
Note : Like we have each different morphology like have shoulders more or less wide, valgus of the elbows more or less pronounced, wrist more or less flexible, hands may be more or less outspread and elbows more or less open during the movement execution.
Use the EZ-bar allow you to do this exercise by avoiding excessive tension on your wrist joints.