Interrupting sitting with moderate-intensity physical activity breaks improves cognitive processing speed in adults with overweight and obesity: Findings from the SITLess pilot randomized crossover trial.

Introduction: Prolonged sitting can acutely reduce working memory (WM) in individuals with overweight and obesity (OW/OB) who show executive function deficits. Interrupting prolonged sitting with brief PA bouts may counter these effects. However, the benefits of such interventions on behavioral and neuroelectric indices of WM and whether neurocognitive responses are associated with postprandial glycemic responses in young and middle-aged adults with OW/OB remain unknown. To address this gap, this study examined the acute effects of interrupting three-hour prolonged sitting every 30 min with 3.5-min moderate-intensity physical activity (MPA) bouts (MPA + SIT condition) relative to sedentary social interaction condition (SOC + SIT) on behavioral measures of WM and the P3b component of event-related potentials (ERP) in young and middle-aged adults with OW/OB.

Method: Nineteen adults with OW/OB (63 % females; 29.9 ± 7.5 years; BMI = 30.0 ± 3.64 kg*m) were included in the SITLess pilot randomized crossover trial. Choice RT and WM were measured before, after, and four times during each condition with 1- and 2-back letter tasks. They were expressed as the incremental area under the curve (iAUC). Choice RT was expressed as d-prime, target, and nontarget accuracy, and RT on the 1-back and nontarget RT on the 2-back task. WM was expressed as d-prime, target accuracy, and RT on the 2-back task. The amplitude of the P3b-ERP component was used to measure attentional resource allocation during both tasks; the P3b-ERP fractional area latency measured cognitive processing before and after each condition. Two-hour postprandial glycemic responses (expressed as iAUC) were measured using an oral glucose tolerance test (OGTT). Time (pre, post) x Condition (MPA + SIT vs. SOC + SIT) interactions and the main effect of Condition (iAUCs) were tested using Linear Mixed Models.

Results: No significant intervention effects on glucose were noted (p = 0.74). Compared to SOC + SIT, MPA + SIT resulted in shorter 1-back target P3b latency (F(1, 17.0) = 5.14, p = 0.037; M = -9.77, SE = 4.31 ms, 95%CI: -18.9, -0.68) at post-test. No effects on behavioral measures were noted (ps ≥ 0.06). However, the between-condition difference in 1-back P3b latency correlated positively with the between-condition difference in RTs on 1-back;shorter P3b latency was related to shorter RTs in the MPA + SIT relative to SOC + SIT (r = 0.65 and 0.55 for target and nontarget trials, ps ≤ 0.02).

Conclusion: Interrupting sitting with short MPA bouts can enhance some aspects of cognitive processing in adults with OW/OB. Future studies are needed to better understand behavioral responses to interrupting prolonged sitting with MPA bouts and the underlying mechanisms.