Your heart is a muscle! Just like any other muscle in your body, it adapts to the demands you place on it. This adaptive ability is important—it means that when you ask your muscles to work hard, your heart adapts by quickening its pace to supply oxygen to the muscles. Any effective cardio program will train the heart to adapt to different intensities. If you only train at one intensity, your heart will do exactly what it is designed to do—it will adapt to that intensity, and your training will be less and less effective. Here at Nimble, we use interval training to continually work the cardiovascular system, where we mix bouts of higher intensity exercise with lower intensity recovery periods.

The next time you’re walking, running or doing cardio in general, try incorporating your own interval training. Go ahead and speed up for 30 seconds and then recover at a slower tempo for a minute. Do this for several intervals, and then allow for a full recovery before going for a second round of intervals. Pay attention to your form and your energy level, since you are asking your body and heart to work at a heightened pace. Start with small increases in intensity and manipulate your program in a progressive fashion, increasing the number of intervals and their intensities over time. Just make sure you have full clearance from your doctor to train at higher cardio levels.