There is "cardio", and then there is real Cardio exercise. What many people, especially women, do for cardio is actually endurance work: Swimming a mile, fast walking, stairmaster, treadmill, elliptical. An hour or four of endurance work per week will keep you moving, but it's not really Cardio for a relatively healthy person.
Real Cardio means training the heart muscle (the invisible muscle) and stressing the cardio-pulmonary system. For the Cardio component of our Fitness For Life program, we recommend some endurance cardio but, more importantly, HIIT cardio training.
What does it do? Primarily, it builds cardiac muscle and cardiac vessels. We need those for life exertions (eg mountain hikes), for endurance, for energy, for our sports, and, sadly, to help us survive our first or second heart attacks. Since most of us will die from cancer or heart disease, why not postpone the latter if we can, and have more energy and life vigor in the process? There's some evidence that it might help postpone dementia too.
HIIT entails maximum sprints, 30-45 seconds, integrated in a regular cardio program. You want your heart rate near you max output, 90% or more. This can be done with swimming, treadmill, stairmaster, Jacob's Ladder, rower - whatever. Best not to undertake this without a stress echocardiogram and your doc to clear you first to make sure you do not drop dead in the gym. That would be embarassing for you and for them.
Customizing your HIIT workout.
If you do 5-10 fully-intense, max effort cardio sprints on your cardio days, you will feel it. A bit of dizziness means you've done your best. Good calis classes offer this too, and you can, of course, exert yourself to your own best level.
Reminder: Whether you do "long-slow" exercises, or do HIIT, or jus take walks or swims, none of these will offer you any meaningful loss of abdominal fat. Fat is nutritional unless you workout 6 hours/day.
