To keep feet warm. In Liberec, they invented a cover for substitute soccer players.
Starting a match in cold weather on the bench will no longer be a problem. Thanks to the smart Hot Boots cover, football players can keep their feet warm while waiting for their chance on the field, helping to prevent potential injuries. This world-first innovation was developed by the Faculty of Textile Engineering at the Technical University of Liberec (TUL).
While players can protect their bodies, heads, and hands on the bench with layers of clothing or a blanket, their feet have often been neglected — or warmed up in clumsy and highly unprofessional ways.
“Football boots are great for playing, but really bad for winter. That’s why warm-ups always took longer for me — in fact, I only really warmed up during the match itself, which then affected my performance. For example, if you play only the second half in January, your feet get painfully cold very quickly, and it’s hard to get going. The same thing happens in reverse — when you come off the field and sit on the bench just in case you’re subbed back in,” explains coach and active player Karel Kozma, describing the issues that led him to his innovative idea.
“Every footballer knows this problem — from the lowest amateur levels to the top international leagues. That’s why I kept thinking: how is it possible that this hasn’t been solved yet in the 21st century?” recalls the graduate of the university’s Faculty of Economics.
About a year and a half ago, Kozma began working with the TUL Department of Textile Evaluation to design an effective solution in the form of textile thermal sacks. These include heating pads, a power bank, and various removable and washable components.
“The player can step into the sack even with football boots on and pull it up to their thighs. The whole system is wireless, and even in extreme cold, it maintains a comfortable temperature of around 25°C. Thanks to the nanomembrane on the outside, the cover is also resistant to rain and wind,” demonstrates Roman Knížek, head of the Department of Textile Evaluation at TUL’s Faculty of Textile Engineering.
Cold Chamber Test
The entire team fine-tuned the prototypes this summer, with Kozma’s colleague spending an entire half-time period inside a freezing chamber along with the warming sack. Even under those extreme conditions, the sack maintained the target temperature of 25°C.
The innovation was later tested by several clubs across different football leagues. All were highly satisfied, and according to Kozma, discussions about possible partnerships are already underway. The system is also designed so that clubs can customize the heated boots and their covers with their logos and team colors.
One Hot Boots unit costs around 14,000 CZK. Clubs can purchase 12-piece packages including a group charging station that makes the equipment manager’s job easier — the full set costs 160,000 CZK. “We’ve already had some consultations, and we know this solution will be interesting for league teams, international clubs, and maybe even the national team one day,” Kozma says with a smile.
Improved Mental Comfort
According to feedback from Kozma’s football colleagues, no one has suffered an injury after using the sack. The boots gave players the feeling of just walking out of the locker room, and warm-up times were shortened. Players also reported feeling more mentally at ease.
“Now that we’ve developed the boots, we want to approach a medical institution with some sample units to conduct a health study in the coming years. That way we’ll have hard data on injury prevention — not just feedback based on feeling,” the inventor notes.
In the future, the heated sacks might not be limited to football benches. They could also benefit skiers or cross-country skiers. Outside of sports, they might help wheelchair users, especially seniors, to stay warm and comfortable.