Spending day after day typing on a computer or doing other activities that require your arms to remain in front of your body could lead to an inability to put your arms behind your back. Your chest muscles tighten when your arms are continuously in front of your body, and in response, your upper back muscles loosen. This muscular imbalance can be repaired through flexibility exercise.
Your chest is made of your ribcage, muscles, tendons, breastbone, ligaments and internal organs such as your heart and diaphragm. Tight chest muscles result in rounded shoulders and poor posture. As you lose flexibility in the muscles surrounding your ribcage, you may have difficulty breathing and find you can't reach behind your back.
A simple stretch that you can perform at work or at home is a doorway chest stretch. This stretch opens your chest and shoulders. To begin, stand in the middle of an open doorway, as if you were walking through, and place your bent right arm on the wall. Your hand is positioned straight up from your elbow and your elbow is in a straight line from your shoulder. If you feel the stretch in this position, remain here and hold. If you need a deeper stretch, slightly turn your body to the left until you feel the stretch in your chest. Hold for 30 to 60 seconds. Repeat the stretch on your left arm. You can repeat the sequence two or three times a day, every day.
Yoga exercise includes poses that will increase the range of motion in your chest. A modified back bend begins with lying on your back with a rolled up yoga mat or towel placed across your middle back and perpendicular to your spine. You will also need a small pillow to support your head and maintain alignment in your neck. Open your arms to the side of your body and rest your arms on the floor with your palms facing up. Your knees are bent with your feet flat on the floor. "Yoga Journal" magazine recommends holding this back bend for two to three minutes.
A torso twist will improve the range of motion around your ribcage. Perform a side twist from a side lying position. Lie on your right side with your knees bent to form a 90 degree angle in your hips. Look up toward the ceiling, raise your left arm toward the ceiling and then allow your left arm to open behind you. Place a support under your left arm -- such as a stack of pillows -- or rest your arm on a couch. Do not let your arm dangle without support. Maintain this position for two or three minutes before repeating on your other side.