The Sensitivity of Differential Ratings of Perceived Exertion as Measures of Internal Load

Purpose: To investigate the sensitivity of differential ratings of perceived exertion (dRPE) as measures of internal load. Methods: Twenty-two, male, university soccer players performed two maximal incremental exercise protocols (Cycle, Treadmill) on separate days. Maximal oxygen uptake (V̇O2max), maximal heart rate (HRmax), peak blood lactate concentration (B[La]peak) and the post-pre protocol change in countermovement jump height (ΔCMJH) were measured for each protocol. Players provided dRPE (CR100®) for breathlessness (RPE-B) and leg exertion (RPE-L) immediately upon exercise termination (RPE-B0, RPE-L0) and 30-minutes post-exercise (RPE-B30, RPE-L30). Data were analysed using magnitude-based inferences. Results: There were clear between-protocol differences for V̇O2max (Cycle 46.5 ± 6.3 vs Treadmill 51.0 ± 5.1 ml·kg-1·min-1, mean difference -9.2%; ±90% confidence limits 3.7%), HRmax (185 ± 13 vs 197 ± 8 b·min-1, -6.0%; ±1.7%), B[La]peak (9.7 ± 2.1 vs 8.5 ± 2.0 mmol·L-1, 15%; ±10%) and ΔCMJH (-7.1 ± 4.2 vs 0.6 ± 3.6 cm, -23.2%; ±5.4%). Clear between-protocol differences were recorded for RPE-B0 (78 ± 12 vs 94.7 ± 9.5 AU, -18.1%; ±4.5%), RPE-L0 (92.6 ± 9.7 vs 81 ± 14 AU, 15.3%; ±7.6%), RPE-B30 (70 ± 11 vs 82 ± 13 AU, -13.8%; ±7.3%) and RPE-L30 (86 ± 12 vs 65 ± 19 AU, 37%; ±17%). A substantial timing effect was observed for dRPE, with moderate to large reductions in all scores 30-minutes post-exercise when compared to scores collected upon exercise termination. Conclusion: dRPE enhance the precision of internal load measurement and therefore represent a worthwhile addition to training load monitoring procedures.