How old would you be if you didn't know how old you was?
--Leroy "Satchel" Paige
You know how many candles lit up your last birthday cake. But that number--your chronological age--may be very different from your physiological age, depending on how fit you are.
Regular exercise can slow several key aspects of aging--such as loss of muscle and bone--allowing physically active adults to perform like someone much younger than their years. Physical declines can start in the 20s if people are sedentary, notes Susan Johnson, director of continuing education at the Cooper Institute for Aerobics Research in Dallas. But at any age, staying fit can slow these declines.
"Physiologically, you can be a lot younger than you are chronologically if you work out," Johnson says.
Exercise can help boost your fitness at any age, so it's never too late to work out and turn back the clock.
Try these tests, adapted from research done at the Cooper Institute. Comparing your scores with the norms for your age and sex can give you an indication of how fit you are. The numbers are also a good baseline to compare yourself with six weeks or six months from now. When you see that you started out able to do only as many sit-ups as the average 60-year-old, then after working out for two months, you could do as many as the average 30-year-old, that's a great motivator.
* Upper body strength. Perform as many push-ups as you can in one minute. Men should have only their hands and toes touching the floor; women can use the "modified" position, with their hands and knees touching the floor. The average score for women in their 20s is 26; in their 30s, 21; in their 40s, 15; in their 50s, 13; and older than 60, 8. The average score for men in their 20s is 33; in their 30s, 27; in their 40s, 21; in their 50s, 15; and older than 60, 15.
* Abdominal strength. Perform as many sit-ups as you can in one minute, keeping your knees bent, feet flat on the floor, arms at your sides and palms down with fingers extended. Curl up only until your shoulder blades lift off the floor, and let your fingers slide forward along the floor about three inches.
An "intermediate" range for women in their 20s is 25 to 45; in their 30s, 20 to 40; in their 40s, 18 to 35; in their 50s, 12 to 30; and older than 60, 11 to 25. The intermediate range for men in their 20s is 30 to 50; in their 30s, 22 to 45; in their 40s, 21 to 40; in their 50s, 18 to 35; and older than 60, 15 to 30.
* Flexibility. To gauge the flexibility of your lower back and hamstrings, tape a yardstick to the floor, then place a foot-long strip of tape perpendicular to the yardstick at the 15-inch mark. Take off your shoes and sit on the floor with your legs straight and feet about 12 inches apart, straddling the yardstick with the "0" end closest to your groin and your heels on the piece of tape at the 15-inch mark. Place one hand on top of the other and lean forward slowly with your legs straight, reaching as far forward along the yardstick as you can without bending your knees. Your score is the point at which your fingertips touch the yardstick at maximum reach.
The average score for a woman in her 20s is 20 inches; in her 30s, 19 inches; in her 40s, 18 inches; in her 50s, 17.9 inches; and older than 60, 16.4 inches. The average score for a man in his 20s is 17.5 inches; in his 30s, 16.5 inches; in his 40s, 15.3 inches; in his 50s, 14.5 inches; and older than 60, 13.5 inches.
* Aerobic fitness. Timing how long it takes you to walk one mile, and your heart-rate response to that effort, is a good indication of your cardiovascular endurance. Scoring is rather complicated, because age, gender and heart rate all must be considered. To receive a free copy of the test with complete scoring, call (800) ROCKPORT and ask for the Rockport Fitness Walking Test.
If you're unhappy with your scores, regular exercise can help you improve them.
"Our research shows that a physically active person has about a 20-year advantage over a sedentary person in terms of function," says the Cooper Institute's Johnson. For example, the institute's studies show that the treadmill time of a 65-year-old active person is about the same as that of a sedentary 45-year-old.
* The American College of Sports Medicine's Fitness Book (Human Kinetics, $13.95) includes numerous self-tests and complete programs to boost your fitness. Figure your fitness profile at the FitnessZone Web site: http://www.fitnesszone.com.
* Calculate your body mass index at Shape Up America's Web site: http://www.shapeup.org.
Fitness runs Mondays in Health.