Here’s what actually goes down inside Apple’s top-secret gym

If you’ve ever wondered where Apple gets the data that makes every watch upgrade better than the last, here’s your answer: It has a super-secret gym. The invite-only space is in a regular-looking, single-story building a few miles from Apple’s headquarters in Cupertino, CA—but what happens inside the fitness den is anything but average.

When Men’s Health visited the gym, the exercise lab was on display in all its glory. There were around 40 employees working out on everything from rowers and treadmills to cable machines, all being monitored by 13 exercise physiologists and 29 nurses. Some of them were even wearing $40,000 masks that analyzed their calorie burn and oxygen consumption, because #technology.

But, that’s not all: There’s also a group fitness studio, a pool, and three climate-controlled temperature chambers (aptly named Higher, Faster, and Stronger) that can be set between subfreezing and 100°F-plus.

So, what exactly is all this top-secret data for? It helps Apple’s motion experts continuously improve the Apple Watch’s algorithms, making the brand’s technology just as accurate for yogis as it is for swimmers and cyclists.

The exercise lab is making Apple’s technology just as accurate for yogis as it is for swimmers and cyclists.

All that hard work is paying off, too: The watchOS 4 upgrade coming this fall offers a lot of cool updates. It will include heart-rate tracking for HIIT, wirelessly pair with cardio machines, remind you to do some guided deep-breathing exercises, and identify when you’re active versus vegging out, adjusting your activity alerts accordingly.

While the technology emerging from the lab is great news for everyone’s well-being, the Apple Watch’s update will also allow your device to hold up to 800 songs. On that note…BRB—going on a nice, long, Beyoncé-fueled run.

Speaking of buzzy technology, this improvement might make your sneakers way more comfortable. And here’s how Google might start helping you diagnose your symptoms.