Feasibility Of A Novel Soccer-specific Motor Task To Induce Mental Fatigue In Soccer

Objective:Most studies investigating mental fatigue(MF)in soccer utilized a computerized Stroop task to induce MF.However,the traditional key-pressing task has been challenged for its lack of soccer-specific characteristic.The limited relevance to real-life soccer made it difficult to bridge the gap between research and applied setting.Therefore,a novel soccer-specific inducing task is in urgent need.This study compared a novel MF inducing task in soccer with the Stroop task,and investigated the impact of induced MF on cognitive and soccer-specific skill performance.Methods:A randomized,counter-balanced crossover design was employed.Fifteen collegiate male soccer players from Shanghai University of Sport randomly participated in three MF-inducing tasks sessions(S1/2/3)48h apart after familiarization.Two of them in S1 and S2 were motor tasks consisting of 10 repeated interval Loughborough Soccer Passing Test(10×LSPT)or LSPT in a clockwise passing order(10×C-LSPT)with each block starting every 2 min.The two tasks share the same movement pattern but C-LSPT is considered to have lower cognitive demands.The third task in S3 was 20-min Stroop task(Stroop-20).All 3 sessions were comprised of a warm-up,pre-tests,20-min MF-inducing task,and post-tests.MF was assessed immediately before and after each task by visual analogue scale(VAS),the cognitive performance in a 3-min Stroop task and the skill performance in one LSPT.VAS was also utilized to assess players’ motivation for every upcoming session.Heart rate(HR)was monitored during two motor tasks(10×LSPT and 10×CLSPT)to evaluate exercise intensity.A two-way repeated measures ANOVA was performed to identify differences in HR,cognitive and soccer skill indicators.Oneway ANOVA was performed for the motivation.The pre-post VAS values were compared by paired t-tests.Results:Participants had similar motivation before 10×LSPT,10×C-LSPT,and Stroop20(approximately 87.0 AU).Two motor tasks shared the same intensity(139±14 VS 138± 14 bpm).Subjective MF increased similarly after 10×LSPT and Stroop-20(+25.4± 10.3 VS+23.4± 10.8 AU,p=0.607).The induced MF by 10×LSPT and Stroop20 had no impact on cognitive performance and movement time,but similarly affected,in a significantly negative manner,on penalty time(+5.9±4.9 VS+5.4±4.2 s,p=0.748)and passing accuracy(-1.4±1.5 VS-1.0±1.3,p=0.465).Two motor tasks shared similar intensity but 10×C-LSPT was inefficient to induce MF.Conclusions:The 20-min repeated interval LSPT could induce a similar MF as Stroop task,but it’s a soccer-specific motor task.The induced MF had detrimental effects on soccer skill performance.The novel motor task is recommended for MF studies in soccer as an inducement task.Practitioners should be cautious about prolonged cognitive demanding skill section of pre-match warm-up to avoid negative effect of MF on upcoming match.