My shoulder gave out when I was doing push-ups. It doesn't hurt, but it seemed to just collapse. What happened?
This could be caused by a number of injuries. A weakened rotator cuff, shoulder instability, Biceps Tendonitis, or Bursitis could all be the reason for your shoulder giving out, though typically these conditions are accompanied by pain. The fact that it didn't hurt is good news, however if you are pretty consistent with push-ups, and this is unusual, you should certainly see an Orthopaedist for an X-ray or an MRI. Unfortunately until you have the shoulder looked at by an Orthopaedist, there is no way to accurately diagnose what happened. But don't be alarmed. More serious conditions are almost always accompanied by pain, swelling or bruising.