Running Speed and Mental Toughness: Effects on Change-of-Direction Speed in Police Students.

Objectives: Effective operational functioning within the tactical domain requires a high integration of physical and psychological capacities under stressful conditions. This study investigated the impact of physical exertion at varying intensities (anaerobic and aerobic running) on subsequent change-of-direction speed (CODS) performance among police students, while evaluating the role of mental toughness (MT) and biological sex. Methods: Thirty police students (36.7% female) completed running protocols at different intensities (300-yard shuttle run and 2.4 km Cooper test), immediately followed by the Illinois Agility Test (IAT) to assess CODS performance. Mental toughness was evaluated using the Mental Toughness Index (MTI). Repeated-measures ANOVA and ANCOVA were used to analyze the main and interaction effects. Results: Initial repeated-measures ANOVA revealed that increasing running intensities significantly degraded CODS performance, demonstrating large main effects for both the anaerobic (F = 56.70, p < 0.001, η2p = 0.661) and aerobic (F = 47.50, p < 0.001, η2p = 0.621) protocols. After introducing mean-centered MT as a covariate, the main effect of Running Speed remained highly significant in both the anaerobic (F = 57.52, p < 0.001, η2p = 0.673) and aerobic (F = 46.01, p < 0.001, η2p = 0.622) models, with no significant univariate interaction effects involving MT or sex on the rate of decline. Mixed ANCOVA showed a significant main effect of sex on absolute IAT times under both anaerobic and aerobic conditions, with males consistently outperforming females. No significant differences in baseline MT scores were observed between sexes (p = 0.507). Conclusions: The findings demonstrate that physical fatigue robustly impairs CODS performance at a parallel rate for both male and female police students. Mental toughness does not neutralize the physiological rate of performance decline under acute fatigue. Practical training programs should integrate physical and psychological conditioning scenarios, while workload management protocols can be uniformly applied across biological sexes.