 This study investigated the effects of adding a cognitive task to high-intensity interval training hit on mental and physical fatigue in tennis players. The results showed that the addition of the cognitive task resulted in higher levels of mental fatigue and a greater increase in perceived exertion compared to hit alone. Despite this, there was no significant difference in physical workload between the two protocols. This suggests that the cognitive task may have been able to increase mental fatigue without decreasing physical workload. This article was authored by Jesus Diaz Garcia, Vicente Javier Clemente Suarez, Juan Pedro Fuentes Garcia, and others.