Here’s a case study for you: Two hundred years ago, the Pima Indians of Mexico lived on the beans, corn, and squash they grew themselves in the Gila River valley. Their farmer lifestyles were active and healthy, and it’s likely that they had killer VO2 max scores, indicating that their body’s utilized oxygen efficiently.

Then in 1853, the United States acquired some of the Pima land through the Gadsden Purchase, and the tribe was split on the U.S.-Mexico border, putting half of the Pimas in what is now southeastern Arizona. The two Pima worlds diverged as white settlers diverted water away from the American Pimas’ land, and soon their farming lifestyle gave way to more sedentary practices. By 1959, the Arizona’s Pimas were living on a reservation, eating the same fat-filled diets as their new neighbors.

It’s easy to recognize the Pima’s loss in this situation. But as a lesson in human health, the tragedy offers a critical lesson on the broad impact of lifestyle. By studying the Arizona Pimas, researchers have come to understand that general activity—or more specifically, VO2 max, which measures how well your body processes O2 during maximal exercise—can have a huge impact on your ability to fight off disease as you grow older. By using exercise to keep your VO2 max high, you can dramatically increase your “healthspan,” or the number of healthy years you have on this planet.

The Pima Tribe and Diabetes

In 1904, there was only one documented case of diabetes among the entire tribe of Pimas. In 1937, there were 21, and by 1965, with their previously active farming lifestyles fully eroded, the Pimas had developed the highest rate of type 2 diabetes ever recorded: Half of adults over 35 had developed the disease.

This is a canary in the coal mine for global public health, says Frank Booth, Ph.D., a University of Missouri biomedical researcher. “What is happening en masse is people are getting overweight and physically inactive, and that leads to all types of inactivity-related chronic diseases,” he says. “About 1 percent of the [American] population had type 2 diabetes in 1970; now we’re approaching 10 percent.” According to the CDC, if something doesn’t change, one in three Americans will acquire the disease by 2050.

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And diabetes isn’t the only rising health concern. Not by a long shot. By looking at previously unanalyzed epidemiological data dating back to the 1970s, Booth discovered strong associations between inactivity and the early onset of 35 chronic conditions—including depression, anxiety, and hypertension. And VO2 max turns out to be the critical link. In the most simple terms, this means that the more oxygen you can pump through your muscles, the likelier you are to grow old without the burden of a chronic disease.

Why VO2 max? “No one knows,” Booth says. It’s complicated, because analyzing maximal oxygen consumption means following the oxygen through the mouth, throat, lungs, blood-brain barrier, pulmonary circulation, skeletal muscle, and so on. But suffice it to say that when VO2 max drops below 43 milligrams (mg) per kilogram (kg) in men and 35 in women, the hardware inside your body starts to break down from lack of oxygen.

How to Test Your VO2 Max

A proper VO2 max test involves running on a treadmill to the point of exhaustion with what looks like a gas mask strapped to you face. Some high-end gyms offer the service, but it can cost $100 to $250. Alternately, fitness tracking devices from Garmin, Fitbit, and Jabra are starting to put VO2 max algorithms in their devices, which allow you to periodically test your body’s ability to process oxygen so you can track changes over time.

For an alternate method, you can also use an online calculator that approximates your VO2 max based on your run time. To reach the optimal level (again—43 mg/kg for men and 35 mg/kg in women), men should aim to hit a one-mile run time of 6:40, and women should aim for 8:01.

If you’re not currently able to hit those times, here are two pieces of good news: One, you can get there by working out, and two, it’s never too late to start.

How to Increase Your VO2 Max

The trick is to add more cardio, and ideally, hard cardio, into your weekly routine. “You want to be above your aerobic threshold, or 60 to 70 percent of your VO2 max [or maximal effort],” Booth says. Thanks to what we know about high-intensity interval training (HIIT), a daily hardcore sweat session of just 16 minutes can significantly raise VO2 max. And as you age and your ability to hit high-intensity workouts declines, you can add more time to maintain your VO2 max.

While intense cardio is the most efficient method, even a brisk walk can yield significant benefits: Copenhagen researchers found that decreasing someone’s daily step count from 10,501 to 1,344 each day decreased VO2 max by 7 percent. Reverse those step-count numbers, and you should see a dramatic improvement in VO2 max.

The Power to Change

Researchers re-ran the Pima Indians study in 2006, this time including the Mexican Pima, who hadn’t given up their daily farming rituals or their fruit-and-vegetable-based diets. The results were predictable: The Mexican Pima had a mere 6.9 percent rate of type 2 diabetes, while their American counterparts had a 38 percent rate. The difference was more than five-fold.

The Arizona Pima were forced into confines that fundamentally shortened their lifespans and led to an earlier onset of chronic disease. Is that just? Not at all. But we can all learn from what happens when regular movement falls out of the daily routine. 

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