INTRODUCTION: Physical game demands in football (soccer) are position-dependent and a large heterogeneity in muscle fiber typology exists among national level players (1). We could expect that it is advantageous for central midfielders, who cover a large total distance, to have a slow typology and for forwards, who sprint a lot, to have a fast typology. At the higher levels this could lead to a selection effect. Furthermore, it was shown that fast typology individuals (FT) fatigue more than slow typology individuals (ST) (2). Therefore, we investigated if muscle typology is different between national level football players who occupy other positions and secondly if FT experience more in-game fatigue than ST. METHODS: Muscle typology was estimated in 147 male professional football players (24.7±4.8yr) by measuring carnosine in the soleus muscle via proton magnetic resonance spectroscopy (3). Players were classified as ST, intermediate typology individuals (IT) or FT based on carnosine content. Our sample comprised 17 goal keepers, 27 center backs, 20 full backs, 45 midfielders, 20 wingers and 18 forwards. Time-motion data were collected by a multi-camera system to measure in-game fatigue as the decay in running activities from the 1st to the 2nd half. Following categories were used: total distance; standing/walking 0-6 km/h; jogging 6-15 km/h; running 15-20 km/h; high speed 20-25 km/h; sprinting >25 km/h; max speed; medium and high acceleration 2 to 3 m/s² and >3 m/s²; medium and high deceleration -2 to -3 m/s² and <-3 m/s². Players` category values were averaged and adjusted for playtime, but only for 59 outfield players who completed at least 5 games with 75 min playtime or more. ANOVAs were used to determine differences in muscle typology between positions and differences in distances covered in each intensity category during the whole game, 1st and 2nd half and decay from 1st to 2nd half. RESULTS: There were no significant differences in muscle typology between positions (p=0.412), indicating that the variance within positions was larger than between positions. FT covered more high acceleration distance in the whole match (+9.3%, p=0.042) and 1st half (+11.9%, p=0.008) than ST players, but no other differences were found between FT, IT and ST considering the whole game, 1st and 2nd half. However, several high-intensity parameters showed a larger decline from 1st to 2nd half in FT players (high speed -10.7%; high acceleration -12.4%; high deceleration -12.7%) than in ST players (high speed -4.3%; high acceleration -7.7%; high deceleration -7.8%; p<0.05) and IT players (high acceleration -6.8%; p=0.011). CONCLUSION: Possessing a particular muscle typology is not required to play a certain football position at the national level. However, it seems that FT are worse at maintaining their high-intensity performance from the 1st to the 2nd half compared to ST.
© Copyright 2022 27th Annual Congress of the European College of Sport Science (ECSS), Sevilla, 30. Aug - 2. Sep 2022. Julkaistu Tekijä Faculty of Sport Science - Universidad Pablo de Olavide. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator