Depending on the activity, gardening can be as tough a workout as lifting weights or riding a bike. "It's all a matter of how much energy you expend," says Barbara Ainsworth of the University of South Carolina, who has compiled a comprehensive list of the metabolic equivalents -- or METs -- of more than 500 physical activities. (A single MET is the amount of energy someone expends sitting quietly, while a 2 MET activity uses twice that much energy.)

Sporting Equivalents
In general, gardening tasks like digging, raking and planting are 4 to 5 MET activities, which make them equivalent to sports such as snorkeling, volleyball and brisk walking. The toughest gardening workouts include mowing the lawn with a push mower, chopping wood, shoveling and tilling. At 6 METs, Ainsworth puts these activities on par with fencing, downhill skiing, softball and doubles tennis.

But working out in the garden offers a unique chance to interact with the environment unmatched by most sports, says Jeffrey P. Restuccio, author of Fitness the Dynamic Gardening Way (Balance of Nature Publishing). "Gardening is a Zen approach to health that gives you exercise, relief from stress, nutritious fruits and vegetables, companionship of family and friends and the aesthetic pleasures of working the nature," he says. "And it's an activity you can do all your life."

A test gardener for Organic Gardening magazine, Restuccio holds a black belt in tae kwon do and evolved his dynamic gardening program while working out in his own "regular suburban plot." Among his "fitness gardening" tips: