World number one female tennis player Swiatek gags during practice

According to Swiatek, gagging when exercising can help her limit the amount of oxygen in her body, thereby increasing endurance.

"I find it difficult to breathe and my heart rate increases more easily," Swiatek said after training in Montreal on August 8. "I won't go into detail because I'm not an expert. But I've been doing this for a while and it works."

Swiatek's fitness coach, Maciej Rysczuk is said to have requested the exercise. Swiatek says the patch on the mouth is annoying, but it's a good exercise for endurance. Polish players pay a lot of attention to the details that can affect the outcome of the competition. She is currently the only one who always brings a psychologist with her to every tournament.

Swiatek is the number one seed in the Rogers Cup women's singles, the important WTA 1000 tournament in preparation for the US Open - where she defended her title. The 22-year-old this season won Roland Garros but lost early at the Australian Open and stopped in the quarterfinals of Wimbledon.

Last year, Swiatek was undefeated 37 games before losing twice in a row at Wimbledon and Warsaw, before being eliminated in the third round in Canada and Cincinnati. "I feel more confident than last year," Swiatek said before the Rogers Cup opening match against Karolina Pliskova on August 9. "I have focused on improving a few points in the game. The transition over the past months has also been better when the tournament in Warsaw takes place on hard courts, instead of clay."

Swiatek, who won the Polish Open last month, has yet to win the Rogers Cup. She lost in the third round last year, so she has the opportunity to earn more points when participating in this year's tournament. After the event in Canada, the Polish tennis player will attend the Cincinnati Open in the US, and then participate in the last Grand Slam of the year. Swiatek has won 15 tournaments in his career, including four this year.