The name says it all. In a reverse triathlon, racers start off in their running shoes, then hop on their bikes and finish in the water. You might think, what's the big deal with changing the order? The order of a traditional triathlon swim/bike/run is based on two things: safety issues and smooth transitions.
All race organizers want to keep their participants safe. Triathlons are grueling tests of endurance, but they shouldn't put anyone's life at stake. The idea behind swimming first is that the open water poses the greatest threat to an exhausted athlete. If the swimming portion were last, then it would increase the chance of a racer cramping up or collapsing with exhaustion in the water and possibly drowning.
Secondly, in competitive triathlons, the transitions between swimming, biking and running are key to maintaining a good time. If you stumble to change your shoes or slip out of your wet suit, you might lose precious seconds from a record-breaking pace. The logic of swimming first is that you can take off a wet suit quicker than you can put one on. That allows for a smoother transition to the bike stage.
For both of these reasons, reverse triathlons are generally shorter "sprint"-style races that are held in warm climates where wet suits aren't necessary. The Whole Foods Pasadena Triathlon, for example, is a reverse triathlon that is held in and around the famous Rose Bowl in California. Participants start with a 5-kilometer (3.1-mile) run around the Rose Bowl (one loop), transition to a 15-kilometer (9.3-mile) bike ride around the bowl (three loops) and finish with three laps in the Rose Bowl Aquatics pool (150 meters or about 500 feet).
For lots more information about triathlons and endurance sports, check out the links on the next page.