The best measure of cardiovascular fitness is VO2max; it’s a gauge of the maximum amount of oxygen you can consume and use in one minute of aerobic exercise. Researchers claim that once you’ve reached 30 years of age, your VO2max decreases about 10 percent per decade, without training.
The good news is that anyone can increase their VO2max by as much as 10 to 30 percent, age is not a factor. And while there are many approaches to this type of training, the best method is high intensity exertion – intervals – where you alternate your heart rate between high and low intensities in the workout.
The idea of training at a high intensity may seem a bit daunting, at first. But if you begin slowly and gradually adapt to the higher intensities, you’ll find that it’s well worth the effort, as interval training is not only the most effective way to improve your VO2max; it’s also the most successful way to lose body fat.
Here’s why…
Interval training stimulates your body to release “growth hormone,” or HGH. This hormone is responsible for height growth in children, but once you finish growing, it changes roles. HGH is the anti-aging hormone in adults; it signals the body to burn fat and grow muscle. Researchers report that a 30 second all-out sprint can increase HGH by as much as 530 percent!
Intervals also protect your muscles so you don’t use them for fuel. This type of training drives your muscles to exert a lot of force. So rather than use them for energy, your body burns more fat, thereby “sparing” your hard earned muscle. This effect is evident if you compare the physique of a top sprinter to that of a top marathon runner.
Another benefit is the “metabolic” effect. Whenever you begin exercising your metabolism speeds up, and then it slows back down when you finish. But with interval training, your metabolism remains elevated, sometimes for as long as 24 hours; so you’re burning fat all day long! The same can not be said for aerobics – once you stop, your body returns to your normal resting metabolism.
It’s best to begin an interval training session with a three to five minute warm-up at a very low intensity. Then alternate periods of high intensity activity (30 seconds) with longer periods of low intensity activity (1-2 minutes). Sessions average about 8-12 intervals per workout, but I’d suggest starting with three to five and gradually work your way up!