Re: C2 Rowing & shin/lower leg pain?
You'll need to identify the exact region where the pain is.
Going from you have said so far - it sounds a bit like when I used to get pain in the shins while running. I had developed a pretty bad case of compartment syndrome in my tibialis (the muscle on the front/outer part of the lower leg. Basically, each time I ran - the muscle would swell inside the sheath and I would experience a burning pain followed by numbness in the lower leg. For your client - it is probably the part of the row, when she pulls herself forward using her legs.
If this sounds similar - I pretty much fixed it with heat/stretching and extremely deep tissue massage... It did take a bit of time though.
Hope this helps