Cardiorespiratory fitness and prefrontal cortex oxygenation during Stroop task in older males

Aim: The aim of the current study was to assess whether executive function and prefrontal oxygenation are dependent on fitness level and age in older adults. Methods: Twenty-four healthy males aged between 55 and 69 years old were recruited for this study. They were stratified by age, leading to the creation of two groups: 55-60 years old and 61-69 years old. A median split based on CRF created higher- and lower-fit categories of participants. Cerebral oxygenation was assessed using functional near-infrared spectroscopy (fNIRS) during a computerized Stroop task. Accuracy (% of correct responses) and reaction times (ms) were used as behavioural indicators of cognitive performances. Changes in oxygenated (Delta[HbO(2)]) and deoxygenated (Delta[HHb]) hemoglobin were measured to capture neural changes. Repeated measures ANOVAs (CRF x Age x Stroop conditions) were performed to test the null hypothesis of an absence of interaction between CRF, Age and executive performance. Results: We also found an interaction between CRF and age on reaction times (p = .001), in which higher fitness levels were related to faster reaction times in the 61-69 year olds but not in the 55-60 year olds. Regarding Delta HHb, the ANOVA revealed a main effect of CRF in the right PFC (p = .04), in which higher-fit participants had a greater A Delta[HHb] than the lower-fit (d = 1.5). We also found fitness by age interaction for Delta[HHb] in the right PFC = .04). Conclusion: Our results support the positive association of CRF on cerebral oxygenation and Stroop performance in healthy older males. They indicated that high-fit individuals performed better in the 61-69 year olds group, but not in the 55-60 years old group. We also observed a greater PFC oxygenation change (as measured by Delta[HHb]) in the high-fit individuals.