You can do this exercise either at the gym or at home. If you prefer to do them at home, you can either purchase free weights or use item like water bottles or soup cans.c 

This exercise works your deltoids (delts), which are your shoulder/upper-back muscles, and your latissimus dorsi (lats), which are the broad muscles in your back.c 

1. To get into the starting form, keep your feet shoulder-width apart with a little bend at the knees. Lean forward slightly at the hips. Start with your hands out in front of you, a weight in each one.
2. Keeping the rest of your body immobile, bring your arms up to shoulder-height, squeezing your shoulder blades together.
3. Perform three or four sets of 15-20 reps.