Apple's expanding health lab

Photo: "Axios on HBO"

After a sit-down interview with Apple CEO Tim Cook for "Axios on HBO," Axios got a tour inside the exercise lab Apple uses to make sure its watch can accurately track your workout of choice — whatever that might be.

Details: Parts of the lab resemble a gym, with dozens of treadmills, rowing machines and other exercise machines. There's also a yoga room and an endless pool, which allows Apple to better track how people are swimming — as different strokes burn different amount of calories.

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What makes Apple's lab quite different from any gym are the bulky masks you see on each of the people working out. Known as a metabolic cart, the machines precisely determine just how many calories are being burned in each activity.

Then there are the 3 temperature-adjustable rooms (dubbed Higher, Faster and Stronger) that can be made extremely hot or very cold.

"We have done over 50,000 sessions of data collection which is almost 100,000 hours of data being collected. That includes over 12,000 unique participants so it’s a very diverse set of data as well which is really important because obviously, everyone’s body is different and we want to understand as much as we can about different types of people."

Apple's fitness director Jay Blahnik

The bottom line: That adds up to a huge bet on health and fitness. The Apple Watch available today is just the beginning.