The Effects of a Unilateral Strength and Power Training Intervention on Inter-Limb Asymmetry and Physical Performance in Male Amateur Soccer Players

The aims of this study were(a)to investigate the effects of a unilateral training program in reducing inter-limb asymmetry in male soccer players;(b)to explore such effects on measures of physical performance and unilateral inter-limb asymmetry.Twenty-four soccer players,randomly assigned to a 6-week unilateral strength and power training(UNI)(n=12)or a control group(CON)(n=12),performed single countermovement jump(SLCMJ),single leg broad jump(SLBJ),single leg drop jump(SLDJ),10-m sprint,and 505 change of direction(COD)speed test.Raw jump scores revealed small to large improve-ments in SLCMJ,SLBJ,and SLDJ reactive strength index(RSI)(g=0.46 to 1.66)in the UNI group,whereas negligible changes were found in the CON group(g=−0.31 to 0.33).Asymmetry indexes showed a moderate significant reduction in the SLDJ(RSI)and in the SLDJ stiffness(K)(g=1.00 to 1.11)in the UNI group.The between-group comparison indicated a significant change in the SLDJ(RSI)and in the SLDJ(K)(g=1.01 to 1.07)in favour of the UNI group.Thus,a unilateral training program seems to be able to reduce between-limb imbalances and foster improvements in jump performance,without any detrimental effects on linear or COD speed times.Given the importance of these physical characteristics for soccer,it is suggested that unilateral strength and power training are incorporated into strength training routines for players of all levels.

Effects of Additional Rifle-Carriage Training on Physiological Markers and Roller-Skiing Performance in Well-Trained Biathletes

Purpose The purpose was to investigate whether an increased amount of training while carrying the rifle affects skiing in well-trained biathletes at submaximal and maximal workloads during a pre-season period lasting a minimum of 12 weeks.Methods Seventeen well-trained biathletes(9 females,8 males)were assigned to an intervention(IG,n=10)or control(CG,n=7)group.Before(T1)and after(T2)the training intervention all participants performed,using treadmill roller-skiing,a submaximal test without the rifle on one day and two submaximal workloads and a maximal time trial(TT)with the rifle on a subsequent day.Between T1 and T2 all participants performed a minimum of 12 weeks of normal training,the only difference between groups being that IG performed more of their training sessions carrying the rifle.Results IG performed more training compared to CG(15.4±1.1 vs.11.2±2.6 h/week,P<0.05),including a higher amount of training with the rifle(3.1±0.6 vs.1.1±0.3 h/week,P<0.001).Speed at 4 mmol/L of blood lactate increased significantly for CG from T1 to T2(P=0.028),while only tended to increase for IG(P=0.058).Performance during the TT,VO2max and the aerobic metabolic rate increased significantly from T1 to T2,although the differences disappeared when including the speed at baseline as a covariate.Conclusion According to the present results,increasing training while carrying the rifle by 2 h/week does not appear to improve skiing performance in well-trained biathletes.In addition,physiological markers at submaximal and maximal intensities while carrying the rifle were not affected after the training intervention.