According to an international research study that looked at a 50-country comparison of child and youth fitness levels, Tanzania is the fittest country, while the U.S. lags in 47th place.

Led by researchers at the Children’s Hospital of Eastern Ontario and the University of North Dakota, the study involved analyzing 20-meter shuttle data, also called the beep test, from 1.1 million kids aged 9 to 17 years old from 50 countries. The beep test is the most popular field-based test of aerobic fitness levels of children and youth. It is also standardized and commonly used around the world.

Following Tanzania in second place was Iceland, then Estonia, Norway and Japan. Mexico took the last spot.

“Kids who are aerobically fit tend to be healthy; and healthy kids are apt to be healthy adults. So studying aerobic fitness in the early years is very insightful to overall population health,” said Justin Lang, lead author, Healthy Active Living and Obesity (HALO) research group, CHEO and PhD student, University of Ottawa. “It’s important to know how kids in Canada or America fare on the world stage, for example, because we can always learn from other countries with fitter kids.”

The study also found that countries with a smaller gap between rich and poor populations appeared to have better overall fitness.