I just went to the physical therapist this afternoon about some pain I've been having in my left arm. My doctor thought it might be tennis elbow, but I only talked to him over the phone. I decided to see a physical therapist so that I could start doing strengthening exercises and stretches. Any little injury is going to be magnified when paddling 750 miles.
The good news is that the physical therapist thought that it was only a strain. She gave me some stretches to do for the next two weeks along with an ice message, and then some strengthening exercises to do the following two weeks. It sounds like this will mostly go away on it's own over the next few weeks.
I think I got the strain by working out too hard. I had increased the weight level on the weight machines, and noticed unusual soreness the following few days. The soreness has gradually diminished, but is still noticeable after about a month. The other advice she gave was less weight and more repititions with the exersize machines.