Relation between total body load and session rating of perceived exertion in professional soccer players.

The aims of this study were to assess (a) the validity of total body load (TBL)-obtained from the global position system (GPS) devices-to quantify soccer training load, assessing its relationship with session rating of perceived exertion (session-RPE) and (b) to analyze the differences in terms of TBL and session-RPE among defenders, midfielders, and forwards. Twenty-two professional soccer players (Spanish first division, season 2007-2008; 26.74 ± 4.2 years; height 179.74 ± 4.04 cm; weight 73.7 ± 3.35 kg) participated in the study. During 13 training sessions composed predominantly of small-sided games, TBL and RPE multiplied by the minutes of session duration were determined using GPS and the 21-point scale, respectively. In each session, data from 10 players randomly selected and classified according to player position (defenders, midfielders, and forwards) were collected. Although session-RPE was a significant predictor of TBL (β = 0.23, p < 0.05), this method only accounted for 5% of the variance in TBL. No significant differences in terms of TBL and session-RPE were found regarding player position. The results of this study suggest that TBL is not a valid measure to quantify training load because it is not strongly correlated with session-RPE. Furthermore, TBL and session-RPE in small-sided soccer games do not vary according to player positions.