Does fitness trump thinness?

Being thin or being fit: Which is more important? Of course, getting to a healthy weight and exercising regularly are both important goals. But to increase your odds of a long, healthy life, improving your cardiovascular fitness should be priority No. 1, according to scientists who study weight, exercise and longevity.

Consider this example: Mara is at her ideal weight, but she can't walk to the bus stop without getting winded. Michael is overweight, but he can walk up three flights of stairs and hardly feel it. Who has the best chance at a long, healthy life?

Most experts would argue that it's Michael. Despite his extra pounds, his three-day-a-week swimming habit boosts his cardiovascular fitness. That, in turn, lowers his risk of dying prematurely (mortality risk).

Even though Mara isn't overweight, she spends long days at her desk and too many nights in front of a screen.

Zero fitness? You have the most to gain

If you're more like Mara than Michael, you can significantly reduce your mortality risk by simply going from no activity to some activity. Pause for a 15-minute daily walk at an easy pace. Build up to 20 minutes and walk faster, and you'll lower your risk even more.

Getting to a healthy weight is still one of the most important goals you can set for yourself. It can help you avoid or control conditions such as diabetes, high blood pressure, joint problems and even pregnancy complications.

But if your goal is living well and living long, work on improving your cardiovascular fitness. In fact, unless you're an elite athlete at peak fitness, you'll gain health benefits every time you add distance, time or intensity to your daily activities.

How to measure fitness

Exercise physiologists gauge fitness by looking at your "VO2 max." That's the amount of oxygen your heart can pump throughout your body when you move. (If you're curious, the V is for volume, the O for oxygen.)

You can have your VO2 measured by an exercise physiologist or other fitness expert, who will perform a simple test to see how your heart rate responds as you add exercise intensity by working harder. You'll come away with a target heart rate matched to your current fitness and a plan for how to keep improving.

You can also gauge your VO2 max yourself by looking at how easy or hard it is for you to perform common daily activities.

Required VO2*

* VO2 is measured as the uptake of milliliters of oxygen per kilogram of body weight per minute. Sitting at rest is equal to 3.5 milliliters of oxygen per kilogram of body weight per minute.

Check off the ones you can do with ease. Then focus on the one that would push your heart rate and breathing into a zone you'd describe as "very hard." That's the one closest to your present VO max.

To improve, add intensity

You can strengthen your heart and lungs by adding distance, time or intensity when you exercise. And the most recent evidence shows that boosting intensity works more efficiently than increasing time or distance.

When you walk quicker, cycle harder or swim faster, it can also take less time to build heart and lung strength. That's an extra perk for the time-crunched.

Even seasoned exercisers can boost their health benefits and improve VO2 max by increasing the duration or intensity of their workouts. Interval training is one way to increase intensity. High-intensity interval training alternates bursts of more-vigorous exercise with intervals of lower intensity exercise. You can modify the intensity and duration of each interval to suit your physical activity goals. In order to make progress, you need to spend as much time as possible at, or close to, your VO2 max.

Whatever your fitness level is today, the payoff for pushing it just a little harder is both immediate and long lasting. Why not get started right now?

Experiments

Try these strategies to boost your cardiovascular fitness this week.

1. Add distance, time or intensity to your walk, run or other workout once this week.
2. Add physical activity to your calendar one extra day this week. Set a specific time for it.
3. Partner up to exercise with a friend or loved one. Move fast enough that it's not easy to talk.