I walk with a baby/toddler in a wrap on my back all the time. Hours and hours if we're at the zoo or museum or something. We both love it, and I haven't had any problems with the extra weight on my joints. However, I do not jog with the baby on my back. It just seems too bumpy for the kiddo. With a small baby (my little one was about 3 months old when we were walking about 2 miles 3 days a week) they don't have enough neck strength to counteract the bouncing. For a toddler it just seems uncomfortable. I would get a jogging stroller. They have shocks built in so baby gets a smoother ride, and are designed for easy maneuverability. Many races would let you take the stroller if finding a babysitter isn't an option for race day.