Aerobic Exercise, AKA Cardio
Aerobic exercise means activity that requires a continuous amount of oxygen to the muscles being used. For heart health, the exercise must raise your heart rate to within the ideal range for your age, usually 70% to 80% of 220 minus your age. Cardio activities include running, brisk walking, swimming and cycling.
High-intensity interval training is a popular approach. Within a cardio workout, you alternate a few minutes of slow or no movement with shorter bursts of the activity at an all-out pace.
Cross training is simply varying your choice of cardio activity within the same exercise session or on different days of the week. This lets you use different muscle groups, helps prevent overuse injuries and keeps things interesting.
Anaerobic Exercise, AKA Strength Training
You need strength training for healthy muscles, essential for everyday activities like just getting up from the sofa. Also called weight training or resistance training, these exercises work various sets of muscles. Strength training is anaerobic, because it doesn't require extra oxygen. It should be done every second or third day. Never strength-train the same muscle groups on consecutive days - they need time to repair after each workout.
Flexibility and Balance
Flexibility exercises, like stretching, and balance work, which can be as simple as toe raises, round out a comprehensive fitness program. These are exercises that keep you limber and steady, and may include disciplines like yoga and tai chi. They should be incorporated at least twice a week but can be part of your daily fitness regimen.