Respiratory and Muscular Perceived Exertion During Official Games in Professional Soccer Players

PURPOSE: The aim of this study was to assess the respiratory and muscular session ratings of perceived exertion (PE) after official soccer matches over an extended period of time (ie, 2 competition seasons) in relation to playing time (>20, 20-45, 45-70, and >70 min) and to determine the between-matches variability of both scores in young professional soccer players. METHODS: Forty players belonging to the same reserve team of a Spanish La Liga club participated in this study. Respiratory and muscular PE were collected 10 min after every game. A total of 841 individual PE ratings were undertaken on outfield players. RESULTS: The differences between match respiratory and muscular load differ depending on the playing time, the respiratory PE being greater for the players that competed less than 45 min (effect size = -0.45 ± 0.45 for the 20- to 45-min group) and the muscular PE greater for players that played more than 45 min (effect size = 0.23 ± 0.30, for the 45- to 70-min group). Match-to-match PE variability was considerable (CV = 14-54%) for all levels of participation, but it was lower the longer the players participated. CONCLUSIONS: Playing time influenced the relative exertion that players' respiratory and leg musculature were exposed to during a game, suggesting that differential PE scores might provide a more accurate evaluation of match-imposed internal load. However, the small-magnitude differences between respiratory and muscular session ratings of PE observed in the current study might question the practical relevance of assessing both scores.