Exercise modulates the dynamics of brain waves, although the magnitude of these changes depends on context and individual characteristics. This study analyzed the global brain-wide modifications induced by a high intensity interval training (HIIT) protocol in two healthy subjects. The protocol consisted of 10 intervals of 40”/20” at 90% of maximal load, with active recovery at 50%. EEG was recorded using 30 channels in resting state with eyes closed at three time points: before exercise (PRE), immediately after (P1), and five minutes post-exercise (P2). Non-parametric tests were used to assess changes in power spectral density within the beta and gamma bands, with preprocessing performed using EEGLab and Matlab. Results showed a marked increase in beta and gamma power after exercise, with a differentiated temporal pattern. In P1, both participants exhibited pronounced increases in gamma, suggesting a transient cortical hyperactivation state associated with neuronal excitability and cortical integration. During P2, a persistence and even amplification of gamma power was observed compared to rest. These findings, consistent with existing literature, indicate that HIIT enhances fast-wave activity (beta/gamma), potentially reflecting neurophysiological adaptations related to excitability, attention, and cognitive processing in the post-exercise state.