If you've only got 15 minutes for a calorie-burning workout, resist the temptation to start at maximum intensity to jump-start your workout. When you're finished, don't hop off your treadmill or elliptical and head straight to the showers. Even for short workouts, you'll want to warm up and cool down for a safe, effective cardio routine.
Step 1
Calculate your target heart rate for an aerobic workout. If you're a male, subtract your age from 220 to get your maximum heart rate, and multiply that number by .70 and .80. If you're a woman, multiply your age by .88 and subtract that number from 206. Multiply that number by .70 and .80. For a 30-year-old male, your target heart rate range for aerobic exercise would be 220 - 30 = 190 X .70 and .80, or 133 to 152 beats per minute. Use an online heart-rate calculator or a personal heart-rate monitor for a more accurate calculation.
Step 2
Move at a moderately intense pace to begin your workout. Warm up by gradually raising your heart rate for several minutes. This will coordinate your heart rate, blood flow and muscle flexibility, resulting in a better workout, according to fitness expert and author Brian Mac. Swing your arms, jog in place, perform jumping jacks or use your exercise machine at a pace comparable to a brisk walk.
Step 3
Begin exercise at a pace that keeps your heart rate in your target range for aerobic exercise. If you have a heart-rate monitor or electronic console on your exercise machine, refer to the data to stay in your range. If you don't have an electronic device, work hard enough that you are breathing hard, similar to a jogging pace. Talk every few minutes -- if you can't talk, you are working too hard and have left the aerobic zone.
Step 4
Add sprints to your workout if you are in good shape. Increase the pace of your exercise to 80 percent to 90 percent of your maximum heart rate for 30 to 90 seconds. Go back to your normal pace for several or more minutes. Add several sprints to your workout to burn more calories.
Step 5
Reduce your pace after 10 minutes of exercise. Slow your movements, so your heart rate lowers to fewer than 100 beats per minute. Stretch if you have time. A cool-down and stretch gradually reduce your heart rate, prevent blood from pooling in your muscles and prevent stiffness and soreness in your muscles later, according to Mac.
