This exercise will strengthen your rhomboids, skeletal muscles on the back. Shoulder position is important, especially if you work at a computer, which tends to encourage forward-slumping posture. “Slumped-over posture can lead to fatigue, back pain and other problems,” Gallagher says. “Learning to keep your shoulder blades back and down helps you restore your body to good posture, both in the gym and everyday life,” she adds.