REVERSE PEC DECK
Since the rear delt muscle is the weakest of the three heads, therefore
target it first by doing the reverse pec deck workout. Sit facing a pec deck machine, keeping your upper torso
as straight as possible. Some bodybuilders grab the handles and slightly
bend their arms at the elbow; lock your arms out as straight as
possible.
In a controlled movement, extend your arms out past your sides
as far as possible during the reverse pec deck exercise. With delt muscle movements, don't squeeze or hold the peak
contraction, but slowly resist as you lower the weight.