The rhomboid muscles of the upper back are responsible for pulling your shoulders backward, as you might do if you were standing at attention. Excessive contraction of these muscles can lead to tension in the upper back. Actions that pull the shoulders forward while broadening the upper back, such as giving yourself a hug, stretch the rhomboids.
The two rhomboid muscles -- the rhomboid major and rhomboid minor -- run from the vertebrae of the lower part of the neck and the upper part of the ribcage to the shoulder blade, or scapula. When they contract, they pull the shoulder blade toward the spine, an action termed retraction of the shoulder. They often work in coordination with the trapezius muscles of the upper back to stabilize the shoulder blade.
Arm Across the Chest Stretches
To stretch your rhomboids, along with the posterior deltoid on the back of your shoulder, stand and bring one arm across your upper chest. With the opposite hand on your elbow, draw the arm toward your neck until you feel a stretch in your upper back. To target the rhomboid muscles on both sides of your back, try the hugging stretch. From a standing position, cross your arms over your chest, with one elbow on top of the other, as if you were hugging yourself. Reach each hand toward the back of the opposite shoulder and lift your elbows until you feel a stretch between your shoulder blades.
Fixed Bar Rhomboid Stretch
The fixed bar stretch requires a strongly anchored horizontal bar, such as a ballet barre or stair rail. Begin standing, facing the bar. The bar should be slightly below chest height. Hold the bar with both hands using an overhand grip. Lean your body backward while straightening your elbows. Allow the weight of your hips and trunk moving backward to pull your shoulders forward, until you feel a stretch across your upper back between your shoulder blades.
Before starting your stretching routine, warm up your entire body with easy aerobic exercise, including dynamic movements for your arms and shoulders. Stretching two to three times per week is effective for improving flexibility, according to the American College of Sports Medicine, although daily stretching will yield greater gains. Hold stretches for 10 to 30 seconds at the point where you feel a slight discomfort or tightness. Don't stretch to the point of pain. Repeat each stretch two to four times.