Have you ever seen a fat sprinter? Not me. And without mentioning any names, have you ever seen a fat aerobicizer? I see them daily. More people perform aerobic exercise than any other fitness activity, yet many of them remain, at various levels, basically unfit. Why this is and what can be done about it? I will answer shortly, but first, let’s look into the basic "science" of aerobics.
Getting Started
Aerobic exercise presents itself in many forms. First, you have walking, followed by maybe jogging, then running. To get you off your feet, you can ride a bike, tug on a rowing machine, or jump into one of those fancy machines you see advertised on TV. Whatever the activity is, if you continue it long enough, you’ll obtain aerobic conditioning. Remember though, exercise should be enjoyable and refreshing. Forget that "No Pain, No Gain" mentality; it’s simply not true for the life-extension enthusiast. You should start your aerobic exercise at a pace that’s comfortable with your beginning level of condition, then gradually accelerate the tempo and frequency of your workouts as you adapt to your new lifestyle. In a short time, you’ll begin to recognize many health benefits.
What is Aerobic Exercise?
Depending on the activity or task at hand, the body innately selects any one of two basic energy sources as fuel. For powerful and explosive tasks that are interrupted with rest intervals; like that in weight lifting, football, etc., the body preferentially chooses carbohydrates as the dominant fuel source; this is called "Anaerobic Metabolism". For long sustained uninterrupted activities, performed at submaximal efforts, the body will utilize oxygen and fat as fuel sources; this is referred to as "Aerobic Metabolism".
Sustained activities are better fueled with fat and oxygen as these two energy sources are the most dense and abundant fuels--you never have to worry about running out.1 In contrast however, running out of carbohydrate fuel [in the form of glucose or glycogen] can happen within seconds of an intense power burst.
The analogy I use when teaching the body’s energy system is that of a rocket ship. As we know, rockets are launched into outer space with several power, or fuel, boosters. The first booster is used to explode the rocket--and it’s massive weight--up off the ground. Once that booster is depleted of its fuel, it disengages and the second booster propels that rocket even further into the sky. Once the final booster is reached, the rocket is dependent on a fuel source that will carry it throughout the rest of its mission, which is a very long time in comparison to the duration of the previous boosters.
Like the rocket ship, your body acts in a similar manner. At first, when activity begins, your body relies on immediate and fast burning fuel sources--the carbohydrates. If you repeat an explosive burst after taking a replenishing rest, the body will again select carbohydrates as fuel for that chore. However, when activity persists for a long duration, like that in most aerobic workouts, your carbohydrate stores deplete and/or are bypassed early in the routine and the body automatically shifts to a fuel mixture of oxygen and fat in the wake of the carbohydrates.
Intensity
Generally speaking, the duration of aerobic exercise should expend no less than 20 minutes with sessions exceeding 30 minutes being ideal. During this time, the cardio-respiratory systems are forced to function above a resting level and at submaximal levels; this is referred to as the "Aerobic Threshold" or "Aerobic Range". Authorities claim that 60% - 85% of Maximum Heart Rate (MHR) is the range for which best aerobic benefits are obtained--I’ll explain more later.