ABSTRACT

　Over months, prior to the weigh-in （24h before the match）， professional boxers（Boxers） typically keep training and reduce their body mass empirically to gain astrength/size advantage over opponents. Using voxel-based morphometry （VBM），resting-state functional magnetic resonance imaging （rs-fMRI）， we included twentymale licensed Boxers （26.7±4.0years） in the time point of one-month before match（Term1, mean body mass index [BMI]: 22.0±1.3） in comparison to seventeen agesex-BMI matched controls（ 27.8±3.7years, BMI: 21.5±1.6）．Then we longitudinally followed the Boxers at the time point of within-one week before the match （Term2,BMI: 20.6±1.3） and one-month after the match（ Term3, BMI: 22.4±1.3）．In Term1,Boxers presented significant higher gray matter density compared to controls, inbilateral anterior insula（ AI）（ left: p<0.001; right p=0.023）， cluster level FWE [familywise error] corrected）， generally representing sensory integration. In Time2 and Time3,Boxers’ posterior cingulate cortex represented correlated gray matter densities withBMI change. In rs-fMRI analysis seeding the AI clusters, significantly lower FC werefound with precuneus （p=0.031） in Boxers. No significant FC were found in Term3.These findings suggest the bilateral AI represented specific structurer in Boxers, and theposterior cingulate cortex represented BMI change before and after the match. Becausethe posterior cingulate cortex has the pivotal role in adopting for the surroundingenvironments, the functional plasticity in Boxers that lower connectivity in precuneuswhich is a part of posterior cingulate cortex, suggests their specificity that they have toreduce their weight regardless of their environments.

DECENTE SPORTS SCIENCE Vol.40/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE