Which is a better source of exercise for both cardiovascular benefits and muscle toning: a strenuous half-hour uphill mountain hike that requires using your arms for some rock climbing, or a steady half-hour swim using rotating strokes? Chrissy

First, let us say that the "best" form of exercise is the one you do. Don't get talked into a certain type of exercise just because you hear it burns more calories. Always choose activities that sound fun to you, so you'll actually do 'em.

Also, when it comes to cardiovascular effects, few activities are inherently better than others. What matters is your intensity--how hard you work. If you get your heart beating fast enough, both swimming and hiking can get you great results; if you trudge through your workout without putting forth much effort, you won't get much from either activity. That said, hiking uphill probably will burn more calories than swimming because it makes more use of your large muscle groups--those in your legs and butt.

As for muscle toning: Hiking uphill can give you a fair amount of tone in your legs, while swimming can firm up your arms. But to really boost your strength and muscle definition, you need to lift weights.

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