The validity of differential ratings of perceived exertion to monitor training load in elite youth football

The internal and external measures of Training Load (TL) are readily monitored within team sports. This is essential as the tactical periodisation protocol means training days are based on different physical fitness components. One popular method to monitor internal TL is the Rating of Perceived Exertion (RPE). Although overall RPE will have discrepancies between two sessions it does not explain underlying psychophysiological differences important in understanding and prescribing training actions. Differential RPE can provide sport scientists and coaches with a better explanation of the mechanisms that determine subjective ratings. The aim of this study is therefore to determine the validity of differential RPE as a measure of internal training load. Twenty-one development squad players from an elite Scottish Premier League Club took part in the study during the 2017/18 in season. Subjects were a mean 18.4 ± 0.9 years of age, mean height 180.4 ± 5 cm and weight 76 ± 7 kg. After each training session, players then responded to two simple questions, “How did the training session feel on your heart and lungs?” and “How did the training session feel on your legs?”. Global Positioning Systems (GPS) were used to collect external load measure. This occurred for each available training session. The greatest total distance covered occurs on match day (MD) minus three days (-3), (7017.4 ± 112.8 m). There is then a significant taper towards the match. Intensity of training was greatest on MD-3, with significantly greater high speed running (21 – 24 km/hr) and sprint distance (>24 km/hr) covered compared to all other training days (249.8 ± 47.5 and 49.6 ± 47.5, respectively, p ‎<0.05). High accelerations (3-4 m.s-2) were found to be significantly greater on MD -2 (7.6 ± 5.7) compared to other training days (MD-4: 4.3± 3.2, MD-25.6 ± 3.6, MD-1: 2.6 ± 2.1). This changes to MD-3 (16.9 ± 5.9) for greatest decelerations (3-4 m.s-2). Overall ratings of perceived exertion are comparable for MD-4 and MD–3 (5 ± 0.6, 5 ± 0.2). There is then a significant fall in RPE over the next two training sessions. Respiratory and lower limb muscular RPE were greatest on MD-3, decreasing towards the match. A typical four-day lead in shows a clear training load pattern, with significant differences between respiratory and lower limb RPE for both MD-4 and MD-3. Lower limb RPE was greater than respiratory RPE (4 ± 0.3, 3.00 ± 0.00, P