Impact of Increased Respiratory Load on Prefrontal Cortical Activation Under Varying Task Complexities of Trail Walking Task

This study examined the effect of breathing rate (BR) on prefrontal cortical (PFC) activation during single-task and dual-task (e.g., Trail Walking Task (TWT)) conditions in a diverse aging population. We hypothesized that higher BR would be associated with increased PFC activation, particularly during dual-task walking. In this cross-sectional study, 45 adults (mean age 50.31 ± 20.19 years; 27 females) walked on an instrumented treadmill at a self-selected pace under single-task and TWT conditions. Resting BR was measured using a smart shirt, and functional near-infrared spectroscopy assessed PFC oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (Hb) during TWTA (numbers only) and TWTB (numbers and letters). Linear mixed-effects models evaluated the effects of BR, task, and their interaction on PFC activation, controlling for age and cardiorespiratory fitness (VO2 max). The results showed significant differences in Hb and HbO2 between single- and dual-task conditions across BR levels. Individuals with higher BR exhibited greater PFC activation during TWT, whereas lower BR was associated with reduced activation and more efficient attentional resource allocation. BR was not associated with walking speed. These findings suggest that higher BR reflects increased neural effort during dual-task walking and highlight breathing as a potential modifiable factor influencing cognitive-motor performance and fall risk.