I am sort of collecting links on people who are athletic on low carbs. This guy’s story is great.
Another person I found that I enjoy reading about is Dr T.:
His blog: http://drtrunning.blogspot.com/
His low carb epiphany (and then the articles forward in time from there): http://drtrunning.blogspot.com/2011/10/my-low-carb-ephiphany.html
Bottom line it appears that as your insulin resistance drops over time (from removing carbs) you transition from a glycogen burning machine to a fat burning machine. You do lose some top end anarobic performance, but that is a small price to pay (if you are not a sprinter) for getting access to a practically unlimited energy supply (fat), increased lactate threshhold, reduced body fat and reduced risk of heart disease.