Author(s): ZHANG, Z., FANG, L., YUAN, P., DING, L., Institution: SHANGHAI UNIVERSITY OF SPORT, Country: CHINA, Abstract-ID: 1390

INTRODUCTION:
Load monitoring in elite male volleyball typically quantifies both external and internal loads and considers their relationship to better understand training responses and fatigue. However, in volleyball, evidence remains limited on whether external-load metrics differ in their ability to predict internal load across training and match contexts, and whether position-related differences in internal load vary by context. Therefore, this study aimed to: (1) compare the predictive ability of external-load metrics for sRPE-TL (sRPE x duration) and TRIMP across different training contexts; and (2) test position differences in sRPE-TL and TRIMP across contexts.
METHODS:
Nine Chinese provincial-level male volleyball players from the same team (outside hitter, middle blocker, opposite, setter) were monitored during 8 matches, 13 technical sessions, 12 tactical sessions, and 11 integrated technical-tactical sessions. Players wore a Polar H9 and Catapult S7 to collect internal load (sRPE-TL and heart rate) and external load, including high-intensity jump count (H-Jump), total jump count (T-Jump), total accelerations (T-Acc), total decelerations (T-Dec), total changes of direction (T-COD), and Playerload (PL). Within each context, linear mixed-effects models were fitted to assess the predictive ability of each external metric for sRPE-TL and TRIMP and to test position differences in sRPE-TL and TRIMP.
RESULTS:
Among all external-load metrics, T-Acc showed the highest explained variance for TRIMP in matches and integrated technical-tactical sessions (R2m = 0.253-0.292), whereas T-Jump showed the highest explained variance in technical sessions and tactical sessions (R2m=0.104-0.341). PL showed the highest explained variance for sRPE-TL in integrated technical-tactical sessions and tactical sessions (R2m=0.273-0.562). T-Dec in matches (R2m=0.589, p<0.001) and T-COD in technical sessions (R2m=0.250) showed the highest explained variance for sRPE-TL. In matches (p=0.011), technical sessions (p=0.001), and integrated technical-tactical sessions (p=0.002), outside hitters showed significantly higher TRIMP than middle blockers. In technical sessions (p=0.008), integrated technical-tactical sessions (p=0.003), and tactical sessions (p=0.003), setters showed significantly higher TRIMP than middle blockers. Opposites were significantly lower than outside hitters in technical sessions (p=0.043) and significantly lower than setters in tactical sessions (p=0.005). No significant between-position differences in sRPE-TL were observed within any context.
CONCLUSION:
In elite male volleyball players, the external-load metrics that best predict TRIMP and sRPE-TL differ across contexts, supporting context-specific selection of primary monitoring metrics. Metabolic load differed between positions across contexts, with outside hitters and setters showing higher metabolic load in most contexts. However, psychological fatigue did not differ between positions.