Real Madrid players are performing a typical stress test, but with a portable system to measure their maximum oxygen uptake.

It's not the first time Madrid have worn the masks, and they shared a video titled: 'The masks are back!' to their YouTube channel. Fitness guru Antonio Pintus is the person behind the idea.

Real Madrid players have been pictured taking part in high-intensity drills while wearing unusual blue masks - so what's the reason for them?

Real Madrid returned to the training pitch today as they continue preparations for Sunday night’s La Liga clash against ...

Los Blancos are turning to an unusual method to test players’ physical output ahead of a busy schedule.

On Wednesday, the Real Madrid players were put through some intense physical tests by new fitness coach Antonio Pintus.A ...

Real Madrid players endure Antonio Pintus' hypoxia mask training at Valdebebas, simulating high altitudes to boost endurance.

The Spanish club's physical trainer Antonio Pintus favours using the K5 masks to measure players' physical condition ...

Join Josh and Ollie as they bring humor and curiosity to face mask testing in this hilarious review! From KN95s and quirky fabric masks to a DIY water bottle creation, watch as they put each mask ...

I Listened to My Own Heart and Lungs With the 'Thermometer of the Future' ...