UPDATE: The scientific way to tell how fit you are is to measure the amount of oxygen you can use while working at a maximum level on a treadmill or cycle ergometer.

The measurement is called "VO2max," which literally means the volume (amount) of oxygen used during maximum work. World-class distance runners have VO2max levels from 80 to 90 ml/kg/min. In other words, each kilogram of tissue can use from 80 to 90 milliliters of oxygen each minute. Fit college students have levels from 40 to 60 ml/kg/min., and cardiac patients may be able to use only 10 to 20 ml/kg/min. at maximum work. Obviously, the higher this number the better in terms of being able to exercise effectively.To determine VO2max, we must measure the amount of air breathed out of a person each minute during maximum work and analyze this air for its content of oxygen. Since air going into the body is about 21 percent oxygen, and we measure the amount of air the person breathes, we can calculate the amount of oxygen used by comparing the amount of oxygen going in with the amount of oxygen coming out. As you might guess, this is a complex test that requires specialized equipment and personnel and is usually done only in research centers and certain sports facilities.

So, how can you estimate your VO2max without the fancy machines? Since VO2max is related highly with how fast you run, tables have been developed to indicate your fitness based upon your run time. The following table is from "Inside Running: Basics of Sports Physiology" by Dr. David Costill (from Running & FitNews, February 1991). Enter your best time and you will have a pretty good idea of your VO2max.:33:00 or faster above 70

36:15 to 33:40 65 to 69

39:30 to 36:50 60 to 64

42:45 to 40:10 55 to 59

46:00 to 43:25 50 to 54

49:15 to 46:40 45 to 49

52:30 to 49:50 40 to 44

53:10 or slower below 39HEALTHFUL LIFESTYLE GOALS

- Exercise. Continue your aerobic exercise at about 30 to 40 minutes a day. Keep doing 25 abdominal curls. Be sure that your feet are free and that you curl the upper body up by bending your back. You can increase the resistance of this exercise by holding your ears (lightly) instead of having your arms across your chest. Increase the squat exercise to 15. Be sure to keep your upper body upright and lower yourself with your knee bend.

- Diet. Begin to eat two to four fruits each day. This is to go along with the two to four cups of vegetables a day mentioned last week. If you are having trouble getting enough vegetables, peel a carrot and eat it before supper or during the day or munch on cauliflower or other veggies for a snack.