Acute Effects Of Different Fatiguing Protocols On Interlimb Asymmetries Of Male Rugby Players During Single-leg Countermovement Jump

Interlimb asymmetry is defined as the difference in function or performance of two limbs.Research shows that it is present in athletes across a range of sporting activities and it may affect performance and injury risk.Evidence on the effect of exercise induced fatigue on interlimb asymmetries is limited and data is inconclusive.Different fatigue-inducing protocols and indicators to detect and quantify interlimb asymmetries may be the reasons for this inconsistency.PURPOSE:The aim of this research was to investigate the acute effects of three types of fatiguing protocols that meet the specific needs of rugby on inter-limb asymmetries detected by single-leg countermovement jumps?SLCMJ?in male rugby players.METHODS:13 male rugby players?age17.31±1.98 yrs,height 180.97±4.43cm,weight 68.82±8.24 kg,Body fat ratio10.41±4.98%,Rugby training period1.27±1.17 yrs,resistance training period2.88±1.11 yrs?from Shanghai University of Sport volunteered to participate in the study and completed three fatiguing protocols in a random order:1)4 sets of75%1RM squats until exhaustion with 1.5 min of rest between sets,2)4 sets of 6×30m repeated sprints with 20 s rest between sprints and 4 min between sets,,and 3)1 set of 30s-Wingate on the bike.Subjects performed 3 SLCMJ for both lower limbs before the fatiguing protocol and 1 SLCMJ immediately after each set of the protocol.Within-session reliability was calculated at baseline using the CV of 3 jump heights?JH?.The average value would be used as the baseline only if CV values were<10%for both legs.JH was used to calculate the asymmetry index?AI?=[100%±(JH_{strong limb}-JH_{weak limb})/JH_{strong limb}].A repeated measures ANOVA was used for the AI_squat and AI_{repeated sprints} and the paired sample t-test was performed for the AI_{Wingate test}.RESULTS:All CVs were<10%for both limbs.AI_squat at baseline was 7.8±6.2%,and it was 15.1±11.9%,10.3±5.5%,7.6±6.8%,and 12.3±8.4%after set 1,2,3 and 4 respectively.AI_{repeated sprints} at baseline was 9.1±5.5%,and it was 8.3±8.0%,10.4±7.1%,8.7±6.4%,and 9.4±6.0%after set 1,2,3 and 4 respectively.Finally,AI_{Wingate test} at baseline was 6.8±4.9%,and increased to 17.1±9.3%after the test.Except for Wingate?P=0.003,ES=1.17?,there was no statistical difference between the AI before and after the fatiguing protocol.CONCLUSION:For collegiate male rugby players,the acute effect of fatigue on inter-limb asymmetries is related to the fatigue-inducing protocol.Our results show that one 30s-Wingate cycling will significantly increase inter-limb asymmetries during SLCMJ.When coaches choose a fatigue-inducing protocol,it is recommended to consider the effect of fatigue on interlimb asymmetries.