There is a great boot camp, meeting every saturday 2:30pm in front of the Reflecting pool by the Lincoln Memorial. Its run by an awesome personal trainer from Unfair Advantage fitness. The first session is free and it is open to everyone. I'm finding its really good for cross-training to build strength and muscle endurance for this years triathlons.
For more information go to the UA-Fitness website; http://ua-fitness.com/ or check out their facebook https://www.facebook.com/UAFitness4U