I have had issues with chostochondritis since July of 2012. I have successfully rehabilitated from it and can now perform movements pain free that used to be excruciating. Because this is a common GST related injury I thought I would share what worked for me to finally overcome it.
Please note that this is worked for me. If you are experiencing chostochondritis see a physical therapist to identify what is the cause of your pain. What worked for me might exacerbate the condition in others.
Chostochondritis is a pain and inflammation in the sternum, where the ribs attach to the sternum. For those pursuing GST this will most likely be caused by dips or back lever. For me it was back lever. A full lay back lever was my goal for the summer of 2012 and as such, I set up a program designed around training back lever 3 times a week (M/W/F). I didn't think this would be an issue as I had trained back lever before and had worked up to a pretty solid advanced tuck back lever. I made good progress most of the summer, working up to a solid straddle BL (maybe 10 seconds) and the ability to hold a full lay for a few seconds. I got excited with my progress and during every workout would try to maximize my volume in the hardest variation I was capable of performing. Towards the end of the summer I started experiencing slight pain in my sternum during back lever. I didn't think much of it and trained through it, which was a terrible idea because it left me unable to perform even a tuck BL without extreme pain in my chest and sternum. Since then I have been rehabilitating and have finally eliminated the final traces of pain. Here are the things I tried, and what eventually worked.
1. Rest. If I had not tried to train through this, I would probably have been able to overcome it in a few weeks, rather than 6 months. Most online resources for chostochondritis recommend rest and advise avoiding any range of motion that aggravates it until the conditions have subsided. For all of my fall semester of 2012 I avoided any heavy pressing, dips, or BL that would aggravate it and instead devoted my time to training for a one-arm chin. I thought that with this much time off I would be able to return to BL pain free. Although I no longer experienced pain in my sternum, every time I tried doing BL or even bodyweight dips on PB, the pain returned. Obviously rest alone was not going to work.
2. Visit physical therapist. This should be the first step for any injury but I didn't get around to it until a few months after the onset of symptoms. The physical therapist at my college said that he could feel that my costal cartilage was swollen, but after performing some movement tests he couldn't figure out why. My pecs weren't tight, my lats weren't tight, nor was anything that he would suspect would cause this swelling. He advised that I rest and if pain persisted, visit a specialist.
3. Self myofascial release. Because the PT could not diagnose the cause of my costochondritis, I decided that I would start doing intense foam rolling daily. I thought I would foam roll every part of my body so that if a tight muscle was pulling on my cartilage, I could maybe alleviate the pain with SMR. All this foam rolling definitely felt great and improved my mobility, but it didn't seem to really affect my symptoms. I could now perform simple pressing like pushups or dips pain free, but BL still aggravated my symptoms.
4. German hang. What ultimately solved my problem was german hang. During december and january I returned to ring work four days a week (following the WODs) and substituted BL variations for GH in warmup and WOD. This did the trick. German hang loosened up something in my chest and shoulders that was causing my chostochondritis. Now whenever I feel the slightest twinge of pain in my sternum, I simply do a set of GH. One set of 30s german hang seems to clear up any pain I have.
I hope that this is helpful to others struggling with pain from BL, muscle ups or dips. My biggest piece of advice is that if you are experiencing pain ( chostochondritis or otherwise) IMMEDIATELY STOP doing whatever aggravates the pain and visit a physical therapist.