Validity of Session Rating of Perceived Exertion Assessed via the CR100 Scale to Track Internal Load in Elite Youth Football Players.

PURPOSE To assess the convergent validity of the Borg CR100® scale to track internal training load (TL) in youth football players. METHODS A total of 19 youth football players (age = 15 [1] y, height = 175.9 [12.3] cm, and body mass = 69 [15.4] kg) were monitored for 27 sessions, including training and games. Internal TL was assessed via session rating of perceived exertion (sRPE) and 2 heart-rate-based methods (Banister training impulse and Edwards TL). The correlations between sRPE and heart-rate-based TL, the differences in individual player intercepts and slopes, and the differences between types of sessions (training vs games) were assessed using a general linear mixed model with magnitude-based inferences. RESULTS Correlations between sRPE and Banister training impulse were very large at overall group level (r = .77; 90% confidence limits, .72-.80) and individual level (range .70-.95). Correlations between sRPE and Edwards TL were very large at overall group level (r = .84; 90% confidence limit, .82-.86) and large to very large at individual level (range .64-.93). A very likely small difference was found in the comparison between games and training sessions for the relationship between sRPE and Banister training impulse. CONCLUSIONS The Borg CR100 scale is a valid method for monitoring TL in youth football players.