In elite U20 male basketball players, creatine kinase levels increase by approximately 98% during acute overload microcycles compared to deload phases, and creatine kinase levels are moderately associated with higher exponentially weighted moving average of session-rated perceived exertion (EWMA of session-RPE).

Intense basketball movements like jumping and landing tear tiny parts of muscle fibers, causing a muscle enzyme called creatine kinase to leak into the blood. At the same time, the damaged muscles release chemicals that signal the brain, making the player feel more tired. The brain combines this physical strain with how hard the player has been working over recent days, creating a lasting sense of effort that matches the level of muscle damage.