[Bill]

You say top of rib cage and below sternum. I'm confused. Sharp pain in the lower ribs on either side (runners used to call it stitches) can come from inhaling too forcefully. I've also felt it just under the collar bone, same reason. Stretching or twisting after packing does it too. If you don't wait for it to heal you'll be sore for a long time. One rule of training is to stop at the first sharp pain, preferably before.
No problem if you want to train, just inhale less. The tables can be done with less than full or diaphragm only ventilation and FRC or empty lungs. You'll have to change the numbers of course.