On page 106 of the ACE Group Fitness Instructor Manual, second edition is an overhand grip reverse dumbbell curl exercise for the posterior deltoid; figure 3.31. The starting position is shoulder blades flexed and internally rotated. The finishing position is labeled “shoulders extended, adducted, and externally rotated.” It seems to me this is not correctly labeled. I would personally describe it as “shoulders flexed, horizontally extended, externally rotated and scapulae adducted.” Also in the text to the top right of figure 3.31 they say to “move into extension, abduction, and external rotation”(isn’t the abduction in the starting position?)Am I right? If so I would like to contact ACE to have this corrected in the third edition.
The strengthening exercise for the posterior deltoid has been updated in the essentials of exercise science which accompanies the 3rd edition of the GFI manual.
The exercise states that this posterior deltoid exercise starts with a position where the shoulders are flexed, adducted and internally rotated and then moves into extension, abduction and external rotation.
We will email you the page from the updated manual.