Drawing upon the nonlinear model of attention focus, the purpose of this study was to compare the intrinsic and intentional dynamics of task-related thoughts (TRT) in trained runners and nonrunners during an incremental maximal test. Fourteen trained runners and 14 nonrunners were assigned to 2 conditions: intrinsic (nonimposed thoughts) and intentional (imposed, task-unrelated thoughts; TUT). A significant effect of running velocity over TUT/TRT dynamics in both groups and conditions was observed (p < .001). Although, all participants received instructions to keep TUT for the entire duration of the test, an initially stable TUT phase was followed by a metastable phase (i.e., switches between TUT and TRT) an a final stable TRT phase nearing volitional exhaustion. The stable TRT phase lasted longer in runners group (p < .05) and included higher probabilities in pace monitoring thoughts subcategory (p < .05). The results revealed that trained runners seem to use TRT (i.e., pace monitoring) to maximize performance, and confirm the nonlinear model of attention focus during incremental maximal run in trained runners and nonrunners.