The Effect Of Breaking Up Intervention Exercise On Executive Function And Prefrontal Cortex Activation In Sedentary College Students

Objective:To explore whether breaking up intervention exercise affects the executive function and prefrontal cortex activation of sedentary college students,and the impact difference of different breaking up frequencies,and further analyze the related brain mechanisms.Methods:Using the International Physical Activity Questionnaire,23 sedentary college students（age 23.0±2.0 years,height 169.3±8.7 cm,weight 61.1±11.0 kg）enrolled in Shandong Sport University were included.Sedentary standard:cumulative sedentary time≥8 h/day and moderate to vigorous physical activity time<150 min/week.In the experiment,each subject participated in three experiments of 5-hour sitting（SIT）,10-minute moderate-intensity walking per 1 hour sitting（1 WALK）and 5-minute moderate-intensity walking per 30-minute sitting（2 WALK）,with 6-hour each experiment,including a 5-hour intervention and 30-minute executive function test pre-and post-intervention.Moderate intensity was determined at 60%-70%maximum heart rate（HRmax）.The order of the experimental tasks was randomized with a washout period of at least one week between the experiments.Executive function was tested before and after the intervention.The inhibition function was measured by the Stroop color word test,the updating function by 2-back test,and the switching function by the More-odd-shifting.Ensuring three valid measurements and a 30-second interval after each trial.Accuracy,reaction time,and speed accuracy were used for statistical analysis.A functional near-infrared spectroscopy system was worn while performing executive functional tests,including 22 channels（ch）.The oxyhemoglobin change value（ΔHb O₂）was used as an indicator of prefrontal cortex activation.The channels were mainly distributed in the frontopolar area（ch2,ch3,ch4,ch5,ch6,ch10,ch11,ch12,ch13,ch17,ch18,ch20,ch21）,orbitofrontal area（ch19）,dorsolateral prefrontal cortex（ch1,ch7,ch9,ch14）,and ventrolateral prefrontal cortex（ch8,ch15,ch16,ch22）in the four brain areas.Statistical analyses were performed using SPSS 19.0 software,and ANOVA with two-way repeated measures was performed to assess changes in executive function and prefrontal cortex activation.Results:The behavioral results showed that the three intervention conditions had significant effects on inhibition function and no significant effects on updating and switching functions.There were time main effects for accuracy（P=0.021）,reaction time（P=0.005）and speed accuracy index（P=0.004）,and an interaction effect between reaction time（P=0.029）and speed accuracy（P=0.045）in inhibition function.Post hoc two-by-two comparisons showed there was a significant decrease in reaction time（P<0.001）and a significant increase in speed accuracy（P<0.001）after the intervention compared to the pre-intervention condition for the 2WALK,with no difference between pre-and post-intervention for the other intervention conditions;for the post-intervention,reaction time in 1WALK（P=0.044）was significantly lower than in SIT,in 2WALK（P=0.007）was significantly lower than in SIT and the speed accuracy（P=0.022）was significantly higher than in SIT.The accuracy（P=0.014）,reaction time（P<0.001）and speed accuracy（P<0.001）in the memory updating function had a time main effect.The switching function accuracy（P<0.001）,reaction time（P=0.011）and speed accuracy（P<0.001）had a time main effect.f NIRS results showed that theΔHb O₂ of ch3（Frontopolar,P=0.027）,ch9（Dorsolateral prefrontal,P<0.001）,ch11（Frontopolar,P=0.016）and ch19（Orbitofrontal,P=0.032）during the inhibition function test had a time main effect,ΔHb O₂ of ch22（Ventrolateral prefrontal,P=0.047）had an intervention condition main effect,andΔHb O₂ of ch22 was significantly lower under 2WALK than under SIT conditions;ΔHb O₂ of ch3（P=0.009）,ch5（Frontopolar,P=0.025）and ch14（Dorsolateral prefrontal,P=0.006）had an intervention conditions?time interaction effects,post hoc two-by-two comparative analysis showed that theΔHb O₂of ch3（P=0.001）,ch5（P=0.019）and ch14（P=0.001）were significantly lower after the in 2WALK post-intervention than pre-intervention;theΔHb O₂ of ch14（P=0.007）was significantly lower in 2WALK than in the SIT post-intervention.TheΔHb O₂ of ch8（Ventrolateral prefrontal,P=0.007）,ch11（P=0.013）and ch16（Ventrolateral prefrontal,P<0.001）had an intervention condition?time interaction effect when the memory updating function was tested.In the2WALK,post hoc two-by-two comparison showed theΔHb O₂ of ch8 was significantly lower compared to the pre-intervention（P=0.012）;In the 1WALK pre-intervention,ΔHb O₂of ch11 had a significantly lower（P=0.032）,post-intervention,theΔHb O₂ of ch11was significantly lower in 1WALK intervention than in SIT post-intervention（P=0.037）;ch16 had significantly higher△Hb O₂ under SIT intervention condition（P=0.001）,significantly lower△Hb O₂ under 2WALK intervention condition（P=0.010）post-intervention compared to pre-intervention,and significantly lower△Hb O₂ in ch16 in2WALK intervention compared to in SIT intervention（P=0.009）post-intervention.There was no main effect of time and intervention condition and no interaction effect of intervention condition?time for all channels when switching function was tested.Conclusion:A breaking up intervention exercise using moderate-intensity walking improves executive function and reduces prefrontal cortical activation in sedentary college students.A breaking up intervention exercise of every 30-minute sitting with 5minutes of moderate intensity walking may be an effective way to change sedentary behavior habits of college students.