Abstract
Exposure to acute prolonged sitting reportedly leads to decreased cerebral blood flow. However, it is unclear whether this exposure translates to decreased cerebral perfusion and executive function or whether simple strategies to break up sitting can maintain cerebral perfusion and executive function. This study sought to answer two questions: in young, healthy adults, (a) does prolonged (3 hr) sitting lead to decreased cerebral perfusion and executive function? and (b) does breaking up prolonged sitting, using intermittent calf raise exercises, prevent changes in cerebral perfusion and executive function? Twenty young, healthy participants (21.7 [2.5] years, 70% female, 25.5 [6.1] kg/m(2)) were randomized to 3 hr sitting with 10 calf raises every 10 min (CALF) and 3 hr sitting without intermittent calf raises (CON). Prefrontal cortex perfusion was assessed using near-infrared spectroscopy to monitor total hemoglobin (tHB) concentration and tissue saturation index (TSI, oxygenated hemoglobin). Executive function was assessed using the Stroop word and color tasks. Following 3 hr sitting, tHb was significantly lower in CALF versus CON (-2.1 mu M, 95% CI [-3.1, -1.1]). TSI was not significantly different between conditions (p = .667). Word (1.6 ms, 95% CI [0.7, 2.5]) and color (1.3 ms, 95% CI [-0.2, 2.8]) completion times were longer (worse) for CALF compared to CON. In conclusion, calf raises decreased both cerebral perfusion and executive function. Simple strategies, such as fidgeting or calf raises, which have been reported to preserve vascular function in the legs, appear not to be sufficient to benefit cerebral perfusion or executive function.