Acute Effect Of Breaking Up Prolonged Sitting On Cognitive Function And Heart Rate Variability In Young Adults

PurposesTo examine the acute effects of break up sedentary behavior on cognitive function and heart rate variability(HRV)in young healthy sedentary adults.MethodThis study included 11 sedentary adults who were physical inactivity of 20-27 years(female:6 and male:5;age:23.7±2.1 years;BMI:21.65±2.49 kg/m2).This study is a randomized crossover experiment with an intervention duration of 9 hours.The subjects were randomly divided into and completed the following three conditions:SIT(continuous sitting):continuous sitting for 9 hours;WALK(walking interrupt sedentary behavior):prolong sitting+7 times 8min/h moderate-intensity walking bouts;WALK+RE(walking combined with resistance exercise interrupt sedentary behavior)continuous sitting+7 times 8min/h moderate-intensity walking combined with resistance exercise bouts(walking and resistance exercise alternately).Washout at least for 5 days between each two intervention experiments.Cognitive function test was measured(Stroop word test,Tail Making Test,2-Back measurement of inhibitory f shifting,working memory respectively)at baseline,end of intervention,7:00 am the next day,statistics accuracy,response time and speed-accuracy performance index.Using Polar RS800CX training watch monitoring HRV for 24 hours(8:30-8:30 the next day).It mainly measures HRV within 1 hour(17:08-18:08)after intervention,5 hours(17:08-23:00)after end of exercies intervention and sleep HRV(23:30-6:20 the next day).One-way analysis of variance was used to compare the differences in HRV at 24h,during sleep,and 5 hours after the end of exercise Intervention under the three intervention conditions;two-way repeated measurement analysis of variance was used to evaluate cognitive function and HRV under the three intervention conditions Intra-and inter-group differences in sexuality over time;Pearson correlations was used to examine the relationship between changes in cognitive function and heart rate variability before and after intervention(baseline-end of exercies intervention),and the use of software PROCESS for SPSS for heart rate variability in intermittently affecting cognitive function in acute sedentary behavior Analysis of mediation effects.Statistical analysis of data was performed using SPSS 24.0 software.P<0.05 was considered statistically significant.Result1.Time had significant main effects on some indicators of cognitive function tests,and there were no significant differences between intervention.Further analysis of the simple effects found that,compared to baseline,Stroop response time was significantly decreased immediately after the end of WALK(P=0.01)and 7:00 am the next day(P=0.04).Stroop speed-accuracy performance index increased significantly after the end of WALK(P=0.01)and at 7:00 am the next day(P=0.01),and Stroop response time of immediately after the end of WALK+RE decreased significantly(P=0.042);In the 2-Back,compared to baseline,the speed-accuracy performance index of WALK+RE immediately after the end of exercise intervention significantly increased(P=0.031).2.Immediately after the end of the acute interrupt sedentary behavior intervention,there was a significant decrease in RMSSD,PNN50,and HF-nu and an increase in LF-nu and LF/HF,that is,increased sympathetic nerve activity and suppressed parasympathetic nerve activity.However,there were no significant differences in 5h,24h,and nocturnal heart rate variability after the three interventions.3.the changes of LF-nu and HF-nu had significant mediating effects on the improvement of inhibition function of acute sedentary behavior interruption[? 1f=-16.81,95%CI(-41.10,-0.65);?HF=-16.86,95%CI(-41.67,-1.04)].ConclusionAcute intermit sedentary behavior can improve the inhibitory function and working memory of young sedentary adults,and WALK+RE can improve more areas of cognitive function than WALK.HRV decreased immediately after the end of intervention,but there was no significant effect on the HRV for a longer time or the period during sleep.Heart rate variability can mediate intermittent intervention of acute sedentary behavior to improve inhibitory function.It is suggested that the moderate inhibition of parasympathetic activity and the enhancement of sympathetic activity in a short time after acute interrupt sedentary behavior may contribute to the improvement of cognitive function.Therefore,in the future,further studies on imaging and blood indexes are needed to provide more sufficient evidence and support for establishing mechanisms.