How is Fitness Measured?

Running is not only a natural human activity and integral part of many sports, it gives us the most accurate way to measure fitness - the oxygen uptake test. This test involves running to your maximum on a treadmill. The speed and incline of the treadmill are gradually increased until you're running at breakneck speed, gasping for breath, wishing you had never heard of Covert Bailey and the oxygen uptake test. Off to the side, a medic waits with resuscitating paddles in case you pass out. (Naturally the test is voluntary.) Sounds like fun, doesn't it? Actually, it's expensive, time-consuming, and, as you can guess, potentially dangerous.

For one minute during this maximum effort, we measure the amount of oxygen that disappears inside your body. If oxygen, a agas, goes in and doesn't come out, why don't you blow up? Obviously, it's because the oxygen is metabolized into other products. To get a high score on the oxygen uptake test, you have to have a healthy heart, lungs, and blood to absorb and transport oxygen, coupled with fit muscles that can combine the oxygen with sugar and fat to produce energy.

Since the test measures the amount of oxygen your body uses, you might ask, "Is this a lung test?" Or you might think it's a running test. Actually, it is neither; it is a "whole-body" test that measures the efficiency of heart, lungs, blood and most of the other physiological functions.

Your ability to use oxygen when your body is working at its maximum is directly related to the number of calories you burn. If you use lots of oxygen when you run you are, by definition, using a lot of calories. An out-of-shape person who gasps and puffs during exercise is not using lots of oxygen. Her body wants it, she breathes it in, but because her absorption and transportation systems are poor, most of the oxygen is puffed right back out. The oxygen uptake test cells us how much of that oxygen you're breathing in is actually being used.

Your ability to use oxygen when your body is working at maximum is directly related to the number of calories you burn.

We realize now that this test measures not just fitness but total body health as well. In other words, as the body's ability to use oxygen improves, physical fitness increases - and you become healthier.

Having a high rate of oxygen uptake means:

• lower blood pressure
• better heat regulation
• stronger tendons and ligaments
• thicker cartilage
• larger muscles
• greater blood volume
• more hemoglobin
• less body fat
• denser bones
• more efficient lungs
• heart pumps more blood with each stroke
• more oxygen extracted from the blood
• more capillaries
• lower heart rate