While overhead extensions of the elbow are a great stretch for the short head of the triceps and a static stretch of the long head, cross bench pullovers or rope pullovers from above create direct functional shoulder extension stress. The long head of the triceps is responsible for this movement as is the serratus, lat, and pec to a smaller degree. But, whenever there is elbow flexion/extension involved (like with overhead extension variations), the short heads of the triceps will joint the party while the long head stays in a static, isometric position.