Inside Real Madrid’s high-tech training: K5 masks explained
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The appearance of Real Madrid players wearing special masks during training sparked widespread controversy following the team’s return to practice after a two-day rest.
The scene was striking, as the mask resembled deep-sea diving equipment more than professional football training gear.
According to media outlets, the masks were worn under the guidance of the team’s physical coach, Antonio Pintus, who is known for his rigorous and unconventional training methods.
This was not the first time Pintus has adopted this type of training.
What are K5 Masks?
Real Madrid uses K5 masks, produced by the Italian company Cosmed, which specializes in physical measurement technologies. These masks are designed to collect precise data on players’ aerobic capacity and physical endurance during high-intensity tests.
According to the specifications on the company’s official website, the mask features a comfortable design that follows the shape of the head, with a flexible ribbed structure to prevent air leakage and an integrated chin support that ensures stability during movement.
How the System Works
The mask is secured to the player’s head with rear straps, while the player also wears a small backpack containing a data receiver.
This device transmits the data collected by the mask instantly via Bluetooth to the technical staff’s computers or tablets.
A single set costs around 30,000 euros (about 35,000 US dollars), and Real Madrid has only a limited number of them at its training center.
If the entire team undergoes testing simultaneously, the club rents additional equipment from external companies.
Multiple uses beyond football
The use of these masks isn’t limited to football; they are also used in a variety of other sports such as swimming, athletics, rowing and cycling.
However, their adoption within football clubs remains relatively limited.
Among the clubs that have adopted this technology, alongside Real Madrid, are Bayern Munich in Germany, São Paulo in Brazil, and Tigres in Mexico.
Why does Real Madrid use them?
These masks allow the technical staff to measure players’ maximum aerobic performance during tests similar to traditional fitness assessments.
The test involves players running back and forth on the field at gradually increasing speeds until they reach their maximum physical capacity.
Unlike most clubs that perform these measurements in laboratories or on treadmills, Pintus prefers to conduct them directly on the field to better simulate real match conditions.
The data collected is analyzed instantly to determine individual and team training programs for the following months, with endurance workouts designed to match each player’s physical condition.
— Real Madrid C.F. 🇬🇧🇺🇸 (@realmadriden) February 4, 2026
Pintus' old approach
Antonio Pintus has been using this technology since his time with Monaco in France in the 1990s.
During his time at Real Madrid under Zinedine Zidane and Carlo Ancelotti, he typically conducted these tests twice per season: once during the preseason and once in the middle of the season.
In the 2021–2022 season, after conducting these tests, the focus shifted more toward explosive training rather than endurance work, during which Real Madrid won the Champions League title.
This method is highly accurate and reliable for evaluating players' physical condition.
🎭 The masks are back! pic.twitter.com/ymQdJwc1kE
— Real Madrid C.F. 🇬🇧🇺🇸 (@realmadriden) February 4, 2026
Differences in approaches in previous periods
During the tenure of former coach Xabi Alonso, the masks were used only in certain individual cases, as the technical staff at the time preferred a different approach.
Close associates of the previous staff considered the reliance on these masks to be of limited benefit for a team that regularly plays two matches per week.
Instead, the physical training approach at the time focused on ball-related exercises and match scenarios, aiming to train the body in more realistic movements such as acceleration, deceleration, and changes of direction.
Dimensions beyond the physical aspect