Objective To examine the effect of elastic band exercise in improving the working memory in aged people, and to explore the potential brain mechanism by functional Near Infrared Spectroscopy (fNIRS).

Methods Sixty aged people were randomly divided into an elastic band group (EBG) and a control group (CG). EBG received elastic band intervention for 16 weeks, 3 times a week, 40 minutes each time, and CG maintained the original living condition. The subjects' prefrontal cortex hemodynamics during the N-back task were measured before and after the intervention.

Results The time×group interaction of reaction time (RT) was statistically significant (P<0.001). The interaction effect of time×working memory load at accuracy was statistically significant (P=0.003). The interaction effect of time×group at rate-correct score was statistically significant (P<0.001).The results of HbO₂ showed that the interaction effect groups×time×working memory load was statistically significant in 9 channels (P<0.002).

Conclusion Regular low-to-morderate-intensity elastic band resistance exercise improved the working memory performance in aged people. The activation of the prefrontal cortex was not significant at low working memory loads, and the activity of the bilateral ventrolateral prefrontal cortex, left dorsolateral prefrontal cortex and left frontopolar cortex area were increased at medium and high memory loads. This optimized prefrontal cortex activation pattern may be the brain mechanism by which resistance exercise improves working memory.