View this exercise on Fitain
Dumbbell Eccentric Tricep Extension
1) Stand tall with the chest up, core tight, head neutral and back flat.
2) Grab the dumbbells with palms facing up (underhand grip). Bend your elbows and lift your triceps up so they're parallel to the floor.
1) Slowly extend your arms so they're fully out in front of you.
2) Pause and squeeze the triceps at the endpoint. Now, bring your arms back to the starting position.