If you want a slim tummy, doing cardio exercise on a regular basis is an important factor. The cardio exercises that are the best for getting toned abs are the ones that not only burn the most calories and fat, but also engage your core muscles while doing so. Diet and strength training are two other key elements to creating a toned stomach.
Overall Fat Burning and Flat Abs
To get your desired flat tummy, you need to burn fat all over your body so that your abs can show through. To burn fat most effectively, understand your target heart rate, which is 50 to 80 percent of your maximum heart rate, or MHR, according to the American Heart Association. You can calculate this number by subtracting your age from 220, so if you're 35 years old, your MHR is 185 and your target zone is 99.5 to 148 beats per minute. Knowing these numbers is helpful for cardio interval training, where you do cardio intervals going from your high target zone to your lower zone. A College of New Jersey study led by Jie Kang looked at workout efficiency and found that men who ran harder and faster at the beginning of their runs burned about 5 to 10 percent more fat overall. More fat burning means a slimmer body overall, including the tummy.
Hit the Road
The cardio that will burn the most calories hands down is running. A 155-pound person running eight-minute miles can expect to burn 930 calories in one hour, according to Harvard Health Publications. Not only is it a calorie shredder, running engages all of your core muscles, including your abs, obliques, back, pelvic muscles and butt. The abdominal muscles contract constantly during a run, per "The Essential Runner" by John Hang, which helps tone the abs. The cardio from running will burn fat and allow the toned abs to show through.
Swimming is another effective cardio workout for a flat tummy, and for those that find running hard on the joints, swimming has the added benefit of being low-impact. A 155-pound person will burn about 750 calories by doing laps for one hour. According to Olympic gold medalist Janet Evans in her book "Total Swimming," swimming works the abs better than any other cardio workout. Freestyle stroke -- the easiest to master -- requires you to rotate your body slightly for each stroke; to maintain alignment as you swim in a straight line your abs and obliques are engaged, according to USA Swimming.
Pedal, Pedal, Pedal
Going for a bike ride is another effective calorie burner that engages your abs. A 155-pound person, cycling at 16 to 19 mph, will burn 892 calories in an hour. Maintaining your balance on the bike engages the core muscles and being out on the road curbs workout boredom, notes Bicycling.com. If being out on the road doesn't appeal to you, consider taking a Spin class that has the same ab benefits and also burns 782 calories for a 155-pound person in an hour-long class, according to Harvard Health Publications.
Jumping rope -- that beloved pastime of your childhood -- is also an effective calorie burner. A 155-pound person can burn off 186 calories by jumping rope for just 15 minutes, according to Harvard Health Publications. You'll be engaging core muscles with each jump, according to "Real Simple" magazine. Mix up the basic two-legged jumping with one-legged jumps, high-stepping jumps -- bringing alternating knees high toward your chest -- and alternating leg jumps by switching from right to left with each swing of the rope.
Muscle Building Workouts
To achieve toned abs you need to build your stomach muscles, in addition to burning off the layers of fat through cardio. According to a 2013 study published in the "Journal of Strength & Conditioning Research" the two best ab toners are squats and deadlifts. While most people expect crunches or sit-ups to top the list, the study found through EMG testing that squats and deadlifts engaged the most muscles in your midsection.
You Are What You Eat
You can't avoid a healthy diet if you want a flat tummy; for that you need to eat fewer calories than you expend. One pound of fat equals 3,500 calories, so if you want to lose a pound a week, you need to reduce your daily calories by 500. In addition, according to "Shape" magazine, high-fiber and low-sodium foods reduce bloating and help flatten your belly. Beans, berries and nuts, especially almonds, help digestion and keep you feeling fuller longer. To further keep bloat at bay, drink eight 8-oz. glasses of water every day to flush out sodium.