Poor posture can cause tightness in your chest because of the muscles being pulled while slouching. Poor posture affects the chest muscles, upper back muscles, muscles in the back of your neck and the muscles that bring your chin to your chest. Yoga provides a variety of health benefits including flexibility, strength, improved muscle tone, pain prevention and improved breathing. The different poses in yoga target specific muscle groups, including your chest, to facilitate stretching and a greater range of motion to relieve tightness. The Upward Bow pose is a specific Backbend pose in yoga that opens up the chest for a thorough stretch. To perform the Upward Bow pose, lie with your back firmly on the floor. Bend your knees and bring your heels as close to the buttocks as possible. Bend your elbows and place your hands, palms down, next to your head with your fingers pointing toward your shoulders. Lift your buttocks off of the floor while pressing your feet firmly against the ground. Press your hands into the ground, straighten your arms and lift your head to form an arch. Keep your arms parallel. Lift your navel towards the ceiling to intensify the pose. Keep your gaze toward the floor while letting your head hang. Stay in the pose for five to 10 seconds. Come out of the pose and repeat up to 10 times. In addition to stretching the chest, the Bow pose also stretches the entire front of the body while strengthening back muscles. This pose also helps improve posture, which may be the cause of the tightness in your chest. To perform the Bow pose, lie flat on your stomach with your arms beside you. Bend your knees while taking hold of your ankles. Bring your feet as close as possible to your buttocks. Keep your knees hip-width apart. Press your stomach against the floor while lifting your thighs, buttocks and chest simultaneously away from the floor. Press your shoulders downward and apart to open up the chest while gazing forward. Hold the pose for 20 to 30 seconds. Come out of the pose and repeat. The Warrior II yoga pose is a standing yoga position that stretches the chest as well as the groin and legs. To perform the Warrior II pose, place your feet firmly on the ground with your spine strait and your arms by your sides. Step back with your left foot while bending your right knee. Rotate your right foot forward and your left foot outward. Align your shoulders with your spine. Lift your arms to shoulder height with palms facing down. Keep your arms straight without locking your elbows. Look forward over your right hand. Hold the pose for up to one minute. Come out of the pose and repeat on the opposite side. The Bridge pose is a backbend yoga pose that lifts your chest towards the chin, while stretching your chest and the shoulder muscles. To perform the Bridge pose, lie on your back with your arms by your sides. Bend your knees and place your feet firmly on the ground hip-width apart. Lift your hips toward the ceiling while focusing your weight on your feet. Place your arms underneath your back. Grasp your hands together or grab your ankles for a more intense stretch. Position your shoulders toward each other. Hold the pose for up to one minute. Come out of the pose and repeat up to two times. Talk to your doctor before beginning any new fitness program. Yoga stretches should not be painful, so come out of the poses if they become uncomfortable. Chest tightness can be symptomatic of more serious health conditions, such as heart problems. Call your doctor immediately if your chest tightness is accompanied by pain in the chest, neck, jaw or arm, building pressure, nausea or shortness of breath.