Changes in markers of body composition of professional male soccer players during pre-season

To evaluate changes achieved in whole-body and regional(upper limbs,lower limbs,and trunk)estimates of body composition,twenty professional male soccer players(7 defenders,7 midfielders,6 forwards)underwent dualenergy x-ray absorptiometry(DXA)analysis at the beginning and end of pre-season.Measures included:mass,fat mass(FM),fat-free mass(FFM),and body fat per cent(BF%).Players’activity during on-field training sessions was monitored using Global Positioning System(GPS)units,with GPS data used to obtain estimations of energy expenditure(EE).Whole-body mass remained unchanged across the pre-season.Moderate significant increases and decreases were achieved in whole-body FFM(Pre:59.58±5.27 kg;Post:60.61±5.18 kg;p=0.001;d=0.87)and FM(Pre:10.60±1.88 kg;Post:9.56±1.81 kg;p=0.001;d=0.85),respectively.Moderate significant decreases were achieved in whole-body BF%(Pre:14.4±2.3%;Post:12.9±2.0%;p<0.001;d=0.94).No significant inter-positional differences were observed for the changes achieved in any global or regional estimate of body composition.Total EE was significantly correlated withΔFM(r=0.65,p=0.002),ΔFFM(r=0.46,p=0.03),andΔBF%(r=0.67,p=0.002).The total EE of pre-season training accounted for 42%,21%,and 45%of the variance inΔFM,ΔFFM,andΔBF%,respectively.These findings suggest that the pre-season period is a suitable time for initiating favourable alterations in body composition following the off-season in elite soccer players.