T.J. Davenport pulls his way to the top of a 100-foot oak during a recreational tree climbing course at Camp Wyman in Eureka, Mo., last month. Such climbs offer good full-body workouts, advocates say.

What's Your Workout: Tree Climbing Ann Koenig is an urban forester for the Missouri Department of Conservation. In her downtime, she's up in the trees -- as a competitive tree climber.

So many of us are trying to get fit and shed some pounds, and working out on a cardio machine such as a vertical climber or an elliptical trainer can help achieve those ends. The two exercise machines ...