This exercise works every muscle in your chest while expanding your rib cage. Make sure to concentrate on flexing the muscles under your pecs while doing this workout. This will isolate your upper abs, serratus muscles, and lower chest. Building these muscles will help cover the visual appearance of your Pectus Carinatum. Remember its not about how much you lift but how you lift it. For those who have Pectus Carinatum you have to really concentrate and isolate those muscles.