I think MMA. At first glance, MMA is similar to boxing in that the sport requires hitting and taking punches, but MMA also requires its athletes to master a variety of fighting styles that they must use during a fight to be better than their opponent. In addition, both MMA and boxing are among the most difficult sports because each fight takes months of grueling training and preparation, unlike the weekly training of football players, for example.
! Https: // avatars .mds.yandex.net / get-zen_doc / 171054 / pub_5accfd081410c3ab8458c995_5acd0e55482677a4ef0529b9 / scale_1200
Some sport cannot be called the most difficult. Any sport begins to be a very difficult activity as soon as it becomes a sport of high achievements. Playing checkers is no easier than running marathons when we are talking about the level of the world championships.