Aerobics: High-Impact Fun What it entails: 45 to 60-minute high-impact workout using repetitive dance-like moves with upbeat music to keep you going   Benefits: Like all cardio exercise (the informal term for any activity that increases your heart rate and involves the large muscles of the body) aerobics strengthens your heart and lungs improves blood circulation and boosts the immune system. It also helps the body release endorphins the feel-good hormone. “It’s better than Advil ” declares Malka Kornreich a certified fitness trainer in Jerusalem with almost 20 years of experience and specialties in prenatal postnatal and pain management. “You can start a class feeling absolutely awful and finish feeling great.”   Calories burned: 200 to 450 per class depending on intensity of workout   How the pros do it: A typical aerobics class includes a five-minute warm-up 20 to 30 minutes of rigorous high-impact moves and five minutes of cool down. You know you’re doing it right when: The American College of Sports Medicine recommends 45 minutes of aerobics five times a week but it’s rare to find a frum woman with that kind of time in her schedule. Even once a week can lengthen your life and make a difference in your health.   Balance with: Aerobics doesn’t include weight-bearing or toning exercises although most aerobics instructors will incorporate this into their classes as well.   Exercise caution: Aerobics is hard on the knees especially step aerobics. Expecting? If you’ve been doing aerobics from the first trimester you can continue normally but be careful when moving quickly so as not to lose your balance. After birth wait six weeks before going back.