And average gym-goers, who juggle work, family and other responsibilities--how would you feel about an all-in-one workout for building muscle and improving your cardiorespiratory capacity? As a personal trainer, the first thing I have my clients do when I meet them for their workouts is warm up. And when I teach any type of aerobics class or even a body toning class, we don''t jump right into the high-intensity stuff -- we warm up first. Walking from your car to the gym does not count as warming up. If you''re getting the drift, you probably realize that warming up is crucial to every type of workout, and any sport, for that matter.

Instead of reinventing the wheel, equipment manufacturers typically take an existing technology and make it more interactive through various computer, video and ergonomic enhancements. The standard workout article typically presents a muscle-building routine and an aerobic workout, then explains how to combine both into a complete training regimen. Equal but separate, to turn an ignominious phrase on its head. But what if muscle building and aerobics could be pursued simultaneously in one session? Competitive bodybuilders could use it precontest to get cut without losing muscle mass, or cycle it into their off-season training to increase their strength. Hardcore ironheads who train till they drop could get there fast following such a double-barreled approach, while fitness competitors could get a full-body workout and burn a ton of calories at the same time.

To build some muscle while doing your cardio, try circuit-training and body-sculpting classes that roll resistance and aerobic training into one continuous routine. That’s just the tip of the iceberg. None of these types of classes is inherently better or worse than others; it depends on where you’ve been and where you want to go. “If you used to run track or play basketball, you should probably try something like a high-low class, which entails a lot of running and jumping,” she explains. “On the other hand, if you aren’t a dancer or a ‘movement’ person, I wouldn’t recommend a funk or a hip-hop class, at least not initially. It’d be confusing and you probably wouldn’t get a good workout.”