Relationship of Pre-season Training Load With In-Season Biochemical Markers, Injuries and Performance in Professional Soccer Players

Abstract

Introduction There is controversy in the literature in regards of the link between training load and injury rate. Thus, the aims of this non-interventional study were to evaluate relationships between pre-season training load with biochemical markers, injury incidence and performance during the first month of the competitive period in professional soccer players. Materials and Methods Healthy professional soccer players were enrolled in this study over two pre-season periods. Data sets were available from 26 players during the first season (2014–2015) and 24 players during the second season (2015–2016) who completed two pre-season periods (6 weeks each). External training load was assessed from all athletes during training using Global Positioning System (GPS). Internal training load was monitored after each training session using rate of perceived exertion (RPE). Before and after each pre-season, blood samples were taken to determine plasma lactate dehydrogenase (LDH), creatine kinase (CK) and C-reactive protein (CRP). Injury incidence and overall performance (ranking of the team after the first five official games of the championship) were recorded for both seasons separately. Results There was no statistically significant difference in mean RPE values of the two-preparation periods (2737 ± 452 and 2629 ± 786 AU, p = 0.492). The correlational analysis did not reveal significant associations between internal and external training load (RPE and GPS data) and biological markers. There was a significant positive correlation between RPE and LDH during the 2015/2016 season ( r = 0.974, p = 0.001). In addition, a significant negative correlation was found between total distance >20 km/h and CRP during the 2015–2016 season ( r = -0.863, p = 0.027). The injury rates for the two seasons were 1.76 and 1.06 per 1000 h exposure for the 2014–2015 and 2015–2016 seasons, respectively ( p = 0.127). Conclusion Our study showed that pre-season training load is not associated with overall team performance. This association is most likely multifactorial and other factors (e.g., technical and tactical level of the team, opponents, environment) may play an important role for the collective team performance. Our findings may help coaches to better prepare their athletes during pre-season.

Are Elite Soccer Teams’ Preseason Training Sessions Associated With Fewer In-Season Injuries? A 15-Year Analysis From the Union of European Football Associations (UEFA) Elite Club Injury Study

“…Our findings run counter to those in a single French professional soccer team where there was no association between preseason training and in-season injury rates, 6 but they extend previous studies in rugby, 25 American football, 21 and Australian football 5,22 where athletes who completed more preseason training were less likely to be hurt during the in-season period. Improved physical fitness and well-developed physical qualities protect players from the demands of the competitive soccer season.…”

“…Only 1 study has directly evaluated the relationship between preseason training and in-season injury risk in elite soccer. 6 There was no association between a single team’s (35 total players) preseason training workloads and in-season injury rates across 2 seasons. To our knowledge, no study has yet compared the preseason training workloads of multiple teams and their association with in-season injury rates.…”

SOS to the Soccer World. Each Time the Preseason Games Are Less Friendly

“…It has been recently revealed that training load during the pre-season (6 weeks) of a professional elite football team may not have an effect on team physical performance during the first five official matches of the season, since no relationship was found between training load and injury rate, inflammation and muscle damage markers (Coppalle et al, 2019 ). One of the most significant findings from an initial Football Association's epidemiological study was the disproportionately high number of training injuries during July, a month that corresponds to the preseason period (Woods et al, 2002 ).…”

Load Measures in Training/Match Monitoring in Soccer: A Systematic Review

“…The sRPE, obtained after the completion of training and/or the match, classifies the general difficulty of the session by multiplying the RPE by the duration of the exercise, in minutes [ 111 ] and, based on the scale of 0 to 10, has been widely used in the evaluation of internal load, both in training and in competition [ 7 , 9 , 10 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 24 , 26 , 28 , 29 , 30 , 31 , 32 , 39 , 61 , 65 , 66 , 67 , 68 , 69 , 70 , 72 , 74 , 75 , 77 , 78 , 79 , 80 , 81 , 84 , 85 ]. On the other hand, Coppalle [ 66 ] and Owen [ 86 ] used the 6–20 scale to determine sRPE. The application of this inventory has often occurred shortly after the end of the training session and/or match (15 to 30 min); however, it was applied by Owen [ 86 ] in the morning after training, in order to ensure that the perceived exertion reflected the whole session and not the last effort.…”