Cardio is any workout in which you elevate your heart rate. Many exercises fall under the umbrella of cardio. This includes walking, hiking, running, biking, rowing or elliptical machines, dancing, playing sports, or HIIT (high-intensity interval training). Activities like jumping jacks, burpees, and jumping rope are also cardio workouts. There is a large body of evidence to support cardiovascular exercise for nearly all aspects of your health. Cardio allows you to improve the health of your cardiovascular and respiratory systems while building muscle and burning calories. As with any exercise during pregnancy, physical changes can require you to modify your cardio to ensure your workouts are safe for you and your baby.