Investigating The Effect Of A High Fat Meal And Prolonged Sitting On Executive Function: A Pilot Study

Prolonged periods of sitting have been shown to reduce cerebral blood flow and autoregulation, which may subsequently impair executive function. Similarly, the consumption of a high-fat diet can negatively impact cerebral perfusion. However, whether prolonged sitting combined with a high fat meal additionally impairs both executive function and cerebral perfusion is unknown. PURPOSE: To investigate the effects of consuming a high-fat meal followed by 3 hours of prolonged sitting on executive function and cerebral perfusion. METHODS: Five young healthy males (Age: 22.8 ± 2.9 yrs; stature 177.7 ± 6.4 cm; mass 78.9 ± 14.3 kg), from a target of 18, were recruited. Following familiarisation, participants completed two randomised sessions of 3 hours of prolonged sitting following the consumption of a high-fat (HF) and low-fat (LF) meal. Each visit was separated by a minimum of 2 and maximum of 7 days. Participants completed a Stroop test (containing both congruent and incongruent trials) and trail-making test (TMT) both pre- and post- sitting period. The TMT consists of two parts, A and B. Continuous wave near-infrared spectroscopy (cw-NIRS) was used to measure cerebral perfusion at AF4 both before (baseline) and throughout each trial. Data was analyzed using two-way repeated measures analysis of variance. Alpha was set at P < 0.1 a priori for preliminary analyses. RESULTS: There were no significant differences between or within trials for completion time for Stroop and TMT part A. Completion time for TMT part B was significantly (p = 0.078, d = 2.2) faster in the low-fat condition compared to HF condition (16.4 ± 4 s vs. 21.6 ± 0.7 s). There were no significant differences in cerebral perfusion between or within groups (p = 0.201). CONCLUSIONS: These preliminary findings suggest that the consumption of a high-fat meal may negatively impact core executive functions measured by TMT Part B, namely working memory and task-switching ability. However, cerebral perfusion, as measured by cw-NIRS, failed to identify a mechanism. This may be a consequence of limited statistical power given the sample size, or uncertainties regarding the sensitivity of cw-NIRS when measuring cerebral perfusion.