Throughout December 2009, I rowed 200K meters on my Concept II indoor rower for their Holiday Challenge. For about the first half of the Challenge, I usually had some light pain in the shoulder, but it was not a big issue. Towards the end, I began to feel like I was adjusting my natural moment to compensate for shoulder pain, and I began to develop secondary issues in my left arm - pain between the shoulder and the elbow and some pain along the forearm too. But I managed to finish the Challenge before Christmas without too much trouble.
Despite the pain, I continued to do my weight-lifting and rowing workouts when possible. I was sick with a bad cold around Christmas and into January, so I wasn't working out as often as usual.
At some point in January 2010, I had to stop doing squats and shoulder presses, since I couldn't get the bar overhead without severe pain. This was worrisome.