Runners and Lungs
A few times recently when working with joggers and runners, particularly those who run long distances, there's been a tendency for tightness in the shoulders. Everyone who runs even for a short distance remembers the tendency to lift your shoulders while running, probably as an instinctive way to make more room for the breath, since the upper lobe of the lungs is right under the collar bone area and in front of the scapula. This tension can permeate the membranes under the ribs, like the parietal peritoneum and the pleura, along with the pericardium, intercostal muscles and diaphragm.
Although it's certainly helpful the release the shoulders, it's also very beneficial to relax those membranes, which will in turn soften the muscles. Even though they're on different layers, everything really is interconnected if not interdependent, and there are some types or areas of restriction that will not release until those more subtle connections are addressed. Gentle compression followed by gradual decompression on the rib cage is one way to take the pressure off of these membranes and their many suspensory ligaments, with the understanding that even a slight compression will be recognized by the organs, heart and vascular system.
In this case, if you notice an increase in sensation of the organs, like increased 'pounding' of the heart, combine a gentle compression on the sternum while the other hand compresses the rib cage on your side. Take a deep breath first, then hold gently, and most likely the thorax will begin to push back out on its own. You can focus on the areas that feel a little sensitive or where the ribs may feel a little stiffer when deciding where to place your hands. If in doubt, make an appointment with a manual therapist for guidance so you'll be sure and feel more comfortable in these types of self-correction. A little self-maintenance along the way enables you to continue your favorite activities for much longer without incident from cumulative tensions leading to some form of dysregulation, reduced energy, or reduced oxygen flow during your activity.