Effects Of Elastic Band Resistance Exercise On Working Memory And Task-related Hemodynamics Of Prefrontal Cortex In The Old-old People

ObjectivesWith the acceleration of the global aging process,the number of the elderly population is growing rapidly,cognitive function decline has become a global public health problem.Executive function is an advanced cognitive function,which includes three core components: inhibition,working memory and shifting.Among them,working memory is greatly affected by age,and the decline of working memory will lead to serious consequences.An increasing amount of research has shown that physical exercise can improve executive function,but the effect of exercise on working memory is controversial.In addition,with the increase of age,muscle strength decreases significantly,seriously affecting the quality of life of the elderly.Some studies have shown that there is a correlation between muscle strength and cognitive function,but the relationship between muscle strength and working memory is still unclear.Therefore,this study begins with exploring the pairwise relationship among muscle strength,working memory and task-related hemodynamics in the elderly.Then we designed and validated the elastic band acute exercise program to improve the working memory of the elderly.Finally,a randomized controlled trial was used to further explore whether elastic band resistance exercise improves working memory and whether it improves muscle strength at the same time.Functional near infrared spectroscopy was used to explore the characteristics of prefrontal cortex activation during working memory.MethodsStudy 1: Eighty-one elderly people were recruited and their muscle strength(grip strength and 30-second sit-up test),N-back task and the activation of the prefrontal cortex using functional near infrared spectroscopy were measured.The nonparametric partial correlation with SPSS22.0 was used to reveal the relationship between muscle strength and working memory,between muscle strength and prefrontal cortex activation during working memory,and between working memory and prefrontal cortex activation.Smart PLS3.0 was used to test whether hemodynamics during working memory played an intermediary role between muscle strength and working memory.Study 2: Twenty elderly people were recruited,N-back task and the activation of the prefrontal cortex using functional near infrared spectroscopy were measured.Repeated measurement analysis of variance(ANOVA)was used to analyze N-back behavioral data and f NIRS data.Study 3: Sixty elderly people were randomly divided into elastic band group and control group according to the proportion of 1:1.The elastic band group received elastic band intervention for 16 weeks,3 times a week,40 minutes each time,and there was no intervention in the control group.The subjects’ grip strength,30-second sit-up,N-back task and prefrontal cortex hemodynamics during N-back task were measured before and after intervention.ANOVA was used to analyze N-back behavioral data and f NIRS data.Results(1)There was a positive correlation between muscle strength and WM,and the task-related activation level of PFC in the old-old people.There was an inverted Ushaped WM load effect between the task-related activation level of PFC and WM,the change of blood oxygen concentration in the PFC did not mediate the relationship between muscle strength and WM.(2)Acute elastic band resistance exercise can improve the WM performance of the elderly and increase the task-related activation level of the DLPFC and FPA in the WM task.(3)16-week elastic band resistance exercise improved the WM of the old-old people,increased the task-related activation level of PFC,and improved the grip strength of the old-old people.It supports the compensation-related utilization of the neural circuits hypothesis.Conclusions(1)The grip strength of the old-old people can predict WM.the greater the grip strength,the better the performance of WM.The greater the muscle strength,the easier the task-related activation of PFC.The activation level and activation pattern of the PFC can predict WM.(2)Acute low-to-moderate intensity elastic band resistance exercise may improve WM by increasing the task-related activation level of DLPFC and PFA.(3)The long-term effect of low-to-moderate intensity elastic band resistance exercise is the accumulation of acute elastic band resistance exercise effect,which may improve WM by increasing grip strength and optimizing PFC activation mode.The effect of the intervention was especially significant for medium-high WM load.