How Fit Are You, Really?

fitness age

Story at-a-glance -

  • Fitness age is based on the concept of VO2 max, which is the maximum amount of oxygen you can take in while exercising
  • Fitness age may be a better indicator of longevity than chronological age
  • High-intensity interval training (HIIT) has been found to improve VO2 max and lower your fitness age
  • You can take an online test to determine your fitness age

By Dr. Mercola

You have a chronological age, the one dictated by the days on the calendar and for which you probably celebrate birthdays each year. But you also have a biological age, which is based on the age of your body’s systems.

Your biological age is not fixed. Rather, it’s influenced daily by the lifestyle choices you make, including exercise, diet, stress, sleep, and more. How your body and mind work at the age of 60, 70, 80, and beyond is the result of a small part, genetics, and a large part, lifestyle habits, particularly those that have persisted over the years.

This is why you may actually be younger or older than your chronological age suggests. One way to find out where you fall on the scale is to measure your fitness age. Your fitness age is part of what makes up your biological age – and it’s said to be a better indicator of longevity than chronological age.

How Is Your Fitness Age Measured… and What Does It Say About Your Lifespan?

Fitness age is based on the concept of VO2 max, which is the maximum amount of oxygen you can take in while exercising. Your VO2 max can be used as a measure of cardiovascular endurance; if yours is below average compared to other people your age, it means your fitness age is actually greater than your chronological age.

On the other hand, a better-than-average VO2 max could mean your fitness age is younger than your age in years. Even better, it’s possible to improve your VO2 max, which means your fitness age can actually get younger as you get older …

The primary problem with using VO2 max to gauge your longevity is that very few people know what theirs is, and finding out typically requires high-tech testing on a treadmill.

Researchers at the Norwegian University of Science and Technology, however, were able to develop an algorithm based on the aerobic capacity, waist circumferences, heart rate, and exercise habits of nearly 5,000 people. This has yielded a method for estimating, quite accurately, a person’s VO2 max.1

Next, the researchers explored whether or not VO2 max actually correlated with lifespan. They analyzed the VO2 max, fitness age, and chronological age of more than 55,000 adults and found a strong association.

Those with the worst readings for VO2 max (85 percent or more below the average for their age, which means they had a high fitness age) had an 82 percent higher risk of dying prematurely than those whose fitness age was the same as, or lower than, their chronological age.2

The authors believe that fitness age may predict premature death better than risk factors like being overweight, having high blood pressure or smoking.

Older Athletes Have Impressively Young Fitness Ages

If you’re looking for some motivation to get up and get moving, consider this: when researchers measured the fitness ages of athletes competing in the National Senior Games (commonly known as the Senior Olympics), the older athletes routinely measured decades younger than their chronological ages.

Dr. Pamela Peeke, an assistant professor of medicine at the University of Maryland, and Ulrik Wisloff, professor at the K.G. Jebsen Center for Exercise in Medicine at The Norwegian University of Science and Technology, who lead the aforementioned study, worked together to determine how lifestyle affects fitness age.

They determined the fitness ages of more than 4,200 senior athletes. While the average chronological age was 68, the average fitness age was 43.3 Dr. Wisloff told The New York Times:4

“This is a massive difference… I had expected a big difference since these people have trained for years. However, I was surprised that it was this big.”

How Fit Are You? Take This Online Test to Find Out

If you’re wondering how the senior athletes’ fitness ages were calculated, and want to figure out your own, you’re in luck. The Norwegian researchers created an online calculator for determining fitness age, which was used by the senior athletes (and which you can use yourself).5

By inputting just a bit of information (such as your age, gender, waist size, height, and exercise habits), it will estimate your level of fitness, giving you both your VO2 max and fitness age. I’m 61 years old, and when I took the test my fitness age was that of an average 31 year old.

If, however, you don’t like what you see, the good news is that you can change it. Dr. Wisloff said, “Thankfully, fitness age can be altered,” and if your fitness age is not as low as you would like “just exercise.”6

Dr. Peeke agreed, and it’s possible to significantly lower your fitness age even if you get a late start. Most of the senior Olympians, for instance, returned to or began exercising regularly in middle age or beyond. She told The New York Times:7

“A majority of the athletes at the Senior Games didn’t begin serious training until quite late in life, including me… We may have been athletes in high school or college. But then, for most of us, jobs and families and other commitments got in the way, at least for a while… So you can start any time… It’s never too late.”

What Happens When You Start Exercising in Middle Age?

Many people don’t begin to think about things like fitness age until they start to get older. By then, you may feel any damage is done and it’s too late to get fit – but this is not case!

Research presented at the May 2014 EuroPRevent meeting in Amsterdam found that men who begin intensive exercise after age 40 get similar benefits to those who started prior to age 30 – as well as show several health advantages compared to men who do not exercise.

For instance, both exercise groups (those who started prior to 30 or after age 40) had resting heart rates of about 57 to 58 beats per minute, much lower than the men who did not exercise (who had resting heart rates of about 70 beats per minute).

The exercising men also had higher maximum oxygen uptake (VO2 max) and similar evidence of exercise-related improvements in heart structure and function. According to study author David Matelot of the French Institute of Health and Medical Research:8

"…despite biological changes with age, the heart still seems – even at the age of 40 – amenable to modification by endurance training. Starting at the age of 40 does not seem to impair the cardiac benefits… It's never too late to change your way of life and get more physically active. This will always be beneficial for the heart and well-being. And there's no need for a high level of training for many hours a week…”

The fact is, if you're fit at 50, you're much more likely to be healthy into your 70s and 80s. And if you’re 50 and not fit, you can change that starting today. In addition to the physical benefits, it will boost your cognitive health as well, as physical exercise has been found to protect against age-related brain changes. Those who exercise the most tend to have the least amount of brain shrinkage over time, and exercise actually causes your brain to grow in size. Other research has shown:

  • Even a small amount of exercise may protect the elderly from long-term memory loss and even help reverse some of the effects of aging.9
  • Women between the ages of 75 and 85, all of whom had reduced bone mass or full-blown osteoporosis, were able to lower their fall risk with strength training and agility activities.10
  • Moderate exercise among those aged 55-75 may cut the risk of developing metabolic syndrome, which increases heart disease and diabetes risk.11
  • Among those who started exercising at age 50 and continued for 10 years, the rate of premature death declined dramatically, similar to giving up smoking and mirroring the level seen among people who had been working out their entire lives.12
  • Compared to those who exercised daily, and often vigorously, sedentary people had a six times greater risk of dying from heart disease over the course of 15 years.13 (There's not a pill on earth that can bolster your life expectancy that much!)

Improve Your Fitness Age with High-Intensity Interval Training (HIIT)

While virtually any type of exercise can improve your VO2 max and lower your fitness age, one of the most efficient ways to do so is to engage in high-intensity interval training (HIIT). If you use the online calculator for determining fitness age, you’ll notice that one of the questions asks about the intensity of your exercise. Reporting that you sometimes “go all out” when you exercise likely improves your fitness age tremendously because it boosts your body's natural production of human growth hormone (HGH), which will help address the muscle loss and atrophy that typically occurs with aging (among other benefits).  
Another question asked on the online calculator relates to your resting heart rate, with a lower resting heart rate being preferred for longevity. HIIT, which includes short bursts of high-intensity activity followed by periods of recovery, has been found to improve both VO2 max and resting heart rate – even if you start after the age of 40. Even 12 minutes of HIIT a week can markedly improve your VO2 max. In one study, one group of men followed a protocol known as 4x4 training, completing four intervals of four minutes of high-intensity exercise (16 minutes a day, the "16-minute group") three times a week for 10 weeks.

The second group exercised three times a week using four-minute high-intensity sessions, for a total of just 12 minutes of exercise a week, or just four minutes a day (the "4-minute group").14 Both groups showed marked improvements. The 4-minute group had a 10 percent increase in VO2 max compared to a 13 percent increase in the 16-minute group. Other research has shown that four minutes of exercise performed at extreme intensity four times a week may improve your anaerobic capacity by 28 percent, and your VO2 max and maximal aerobic power by 15 percent in as little as six weeks.

For comparison, those who performed an hour of steady cardiovascular exercise on a stationary bike five times a week only improved VO2 max by 10 percent, and their regimen had no effect on their anaerobic capacity.

A Comprehensive Fitness Program for Health and Longevity

HIIT should be just one component of your fitness program. I also recommend regular strength training, which can be used as a form of HIIT if you use very slow movements. Dr. Doug McGuff has helped me understand how super-slow weight training might be an even more superior form of high-intensity training, compared to high intensity cardio. By slowing your movements down, you're actually turning them into high-intensity exercise.

The super-slow movement allows your muscle, at the microscopic level, to access the maximum number of cross-bridges between the protein filaments that produce movement in the muscle. You can perform the super-slow technique with many strength-training exercises, such as hand weights, resistance machines, bodyweight exercises, or resistance bands. However, whole-body fitness isn’t only about exercise.

While extremely important, exercise can’t counteract the ill effects of long hours spent sitting, which is another major risk factor in premature death and disability. In addition to regular exercise, you’ll want to sit as little as possible (less than three hours a day) and move regularly. I recommend striving for 10,000 steps each day (a pedometer or wearable fitness device can help you keep track). Together, this can help you get your fitness age as low as possible, no matter what your current chronological age. Finally, adding in a healthy diet, stress management, and proper sleep will round out your wellness program so your biological age as a whole will continue to fall.

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