The Rear Delts are one of the most important muscles in the upper body. However, most people neglect them or train them incorrectly. A rounded back and hunched shoulders is a recipe for long-term hunching and injury. Doing too many chest days can also lead to excessive hunching. When you increase the size of the chest muscles, relative to the back, the upper body becomes hunched over. The back muscles become weaker than the front muscles, and are unable to pull the shoulders back. So, if you are sitting hunched over a desk all day you probably need more rear deltoid workouts.
The rear deltoid fly machine provides a uniform resistance throughout the range of movement and helps to pull your shoulders back. This is important as it reduces the shoulders hunching forward. Rear delt flies/rows have many benefits. These include: better posture, better stability during pressing exercises and reduced risk of shoulder injury.
When doing the rear delt fly/row machine, it can be tempting to go heavy. However, the rear delts are not the strongest muscles in the body. Using too much weight compromises the benefits of the exercise and can even cause injury. If you are interesting in reading a little more about this topic check out the website below.