Body-Mass Index

Body-Mass Index (in percentages):

Slightly underweight: <20.7
Normal weight: 20.7-26.4
Slightly overweight: 26.4-27.8
Overweight: 27.8-31.1
Very overweight: 31.1-45.4
Morbidly obese: >45.5

Slightly underweight: <19.1
Normal weight: 25.8-27.3
Slightly overweight: 25.8-27.3
Overweight: 27.3-32.2
Very overweight: 32.3-44.8
Morbidly obese: >44.8

Each body-composition test has a statistical margin for error, so select one test as a baseline. To track your progress over time, have the test done by the same person at the same place to provide the best indication of changes in your BMI.

“Your aerobic capacity and your cardio conditioning are related”

Your aerobic capacity and your cardio conditioning are related because the heart and lungs work together to draw oxygen into the body, to send it out through the bloodstream, and to reprocess it. The cardiovascular system refers to the organs involved in this whole process, and your endurance is a function of your cardiovascular health. The entire heart-lung system is referred to as the cardiopulmonary system. To test the efficiency of your heart and lungs, the trainer will measure your heart rate.

Heart rate is fitness-speak for pulse—in other words, the number of times your heart beats each minute. Your resting heart rate is your pulse before you even get out of bed in the morning. (Because trainers don’t make early-morning house calls, they get an approximation by checking clients’ heart rates when they are sitting down quietly.) The normal adult heart-rate range is 60 to 90 beats per minute. If you already are in reasonable shape, your pulse probably will be at the lower end of the range. If you are sedentary or over-weight, it probably will be at the upper end of the range. When you begin working out, your heart rate will rise; when you stop, it will return to its resting rate.

To determine your aerobic fitness, a trainer or exercise physiologist will put you through a submaximal test, or submax for short. You might use a stationary bicycle or a treadmill for about 15 minutes while your heart rate and blood pressure are monitored. The intensity at which you work will be increased every few minutes until you are working at 75 to 85 percent of your maximum. A simpler test requires you to step on and off a 10- to 12-inch-high step and take your pulse after three to five minutes.