Cardio Exercise: Maximize Muscle Burn (cont.)

"The American College of Sports Medicine and the CDC recommend, for health, that adults should accumulate 30 minutes of moderate-intensity physical activity on most days of the week," says Kravitz, who is also a coordinator of exercise science at the University of New Mexico. "And to improve cardiovascular endurance, they recommend 20 to 60 minutes on three to five days per week."

Now that you know the benefits of cardio exercise, where should your heart-pumping fitness plan begin?

Getting Into the Zone

To help you make the most of your cardio exercise workout -- help your heart, increase muscle, and lose fat -- Denise Austin, fitness expert, author of seven books, including Shrink Your Female Fat Zones, and star of 50 fitness videos, gives WebMD some tips.

"To reap all the benefits of a cardio workout, you should sustain your workout for 20 minutes or more -- I do 30 minutes myself -- on a schedule of about three to four times per week," says Austin.

Not only that, but you need to get in the zone, which calculates into burning calories and fat.

"The best way to find out if you are burning fat is to take your pulse halfway into your cardio workout for six seconds, then add a zero to that number," Austin tells WebMD.

This number is your heart rate per minute.

Next, calculate your zone.

"Take the number 220, then minus your age, then calculate 70% of that number for your target beats per minute," says Austin, and that's your zone. "If your heart rate halfway through your workout is over that 70% mark take it down a level, and if under, pick up the pace."

Not a math wiz? There are easier ways to figure it out.

"Another great way to find out your zone is to get a pulse monitor, which takes the math out of it," says Austin. "Or very simply, take the talk test: while you are doing aerobics, talk a sentence. If you are too winded to finish the sentence, you are overdoing it, or if it's too easy to say, kick it up a notch!"

Getting Cut With Cardio

If you're looking for ripped abs and toned arms, interval training will help get you there -- especially if you throw in some weights.

"I love interval training because it consistently jump-starts your metabolism," says Austin. "Let's say you are walking -- you could power-walk really fast for three minutes to get the burst of calorie burn, and then walk calmly and slowly for one minute, which offers recovery. By switching back and forth, you push the muscle and let it relax over and over and this gives you maximum results." You can do interval training on any type of cardio exercise machine -- alternating a high intensity with a more moderate level.

Austin suggests doing weights during your recovery time, such as bicep curls or tricep toners, to reap the benefits of both cardio exercise and weight training, and along with interval training, add dedicated weight sessions to your regimen to burn fat and sculpt muscle at the same time.