Coach and athlete perceptions of internal training load in U-16 male water polo: an exploratory single-team mixed-methods case study

The coach-player relationship plays a role in determining athletes’ performance and development. Monitoring internal training load (ITL) through the session rating of perceived exertion (sRPE) scale offers an accessible way to assess exertion, but discrepancies often arise between coaches’ and players’ perceptions. This study aimed to compare coaches’ and players’ perceptions of ITL in U-16 male water polo, examine differences across training intensities, and explore qualitative perceptions of the usefulness and limitations of the RPE scale. A sequential explanatory mixed-methods design was used. Quantitative data were collected from one coach and fifteen players over 24 weeks. The coach recorded the session rating of intended exertion, while players reported their sRPE. Qualitative data were obtained from a focus group ( n = 6) and a semi-structured interview with the coach, and analysed using a hybrid deductive-inductive thematic analysis. The coach reported higher intended training loads (sRIE: 598 ± 171.8 AU) than those perceived by the players (sRPE: 516 ± 151.4 AU), although most weekly differences were not statistically significant ( p > 0.05). One microcycle showed a significant difference ( p < 0.05), and several demonstrated moderate-to-large effect sizes, suggesting context-specific perceptual differences. Qualitative findings revealed that both coach and players valued the scale as a tool for monitoring, reflection, communication, and planning adjustment, despite challenges related to recording consistency and the subjective interpretation of effort. The integration of quantitative and qualitative findings provided a more comprehensive understanding of TL monitoring within this exploratory single-team study.