Recently, I was doing A LOT of trail running to get out and enjoy living in Santa Barbara. As a well-trained athlete, the engine was there and I logged a few multi-hour runs without any run-specific training. The result was very angry feet and leg muscles. Whenever you're branching out into new sports, don't make the mistake of thinking you're uber-fit and just jump right in. The small ligaments and tendons that don't get used will pay the price even if your bigger muscles and cardiovascular system can handle it.
Check out the interview I did with Riley Missel about some of my running struggles as a pro paddle athlete: