A new study has found that interrupting prolonged sitting with a minute of half-squats every 20 minutes improved blood flow to the brain and, with it, cognitive functioning and concentration. This simple exercise could be done at work or home to provide a brain boost.
We all know that sedentary behavior – sitting at a desk all day, say, or sitting on the couch watching TV for long periods – can negatively affect our health. Previous research has suggested that it may even decrease blood flow to the brain, thereby compromising executive function, a set of skills crucial to planning, focusing, memory and multitasking. And studies have found that increased blood flow to the brain reduces dementia risk.
A new study has investigated the effects of prolonged sitting, with and without interruptions, on cerebral blood flow and executive function.
The researchers recruited 20 healthy young adults (45% women) with a mean age of 21. They excluded people who regularly engaged in moderate or vigorous physical activity, smokers, those with a history of cardiovascular or cerebrovascular disease, and those on medication that affects cardio- or cerebrovascular health.
Participants were divided into a control group, who sat for three hours without interruption, and an intervention group, who sat for the same time but did one minute of half-squats every 20 minutes. To perform the half-squats, participants crossed their arms across their chests and bent their knees to 90 degrees at a rate of one repetition every four seconds. Being a crossover study, participants spent time in both groups.
Blood pressure (BP), heart rate, and blood flow through the internal carotid artery (ICA) – representing 75% of total blood flow to the brain – were measured at intervals during the sitting period. Pre- and post-sitting, participants completed a visual analog scale (VAS) for mental fatigue, concentration, and motivation; a Color-Word Stroop Test (CWST), which measures executive processing abilities; and a Trail-Making Test Part B (TMT-B), which measures cognitive and executive functions.
In the CWST, participants are asked to quickly identify if the words "red", "blue", "yellow", "green" and "black" are printed in color ink that corresponds to the written word. TMT-B requires participants to trace lines that correspond with correct alphanumeric combinations: A-1, B-2, C-3 and so on.
The researchers found that, compared to the control group, those who performed intermittent squats responded more quickly to both the incongruent (words that don’t match the color ink they’re printed in) and congruent (color in and word match) conditions of the CWST, and completed the TMT-B more quickly. However, accuracy in performing each task was unchanged between the groups.
The control group reported more significant decreases in concentration and larger increases in mental fatigue than when they exercised. When participants were sedentary for between 10 and 180 minutes, ICA blood flow decreased by 3.7%, compared to a slight (0.3%) increase when they exercised.
“The major finding of the present study is that in response to 3 h sitting, half-squat interruptions could improve some aspects of executive function,” said the researchers. “This effect may be explained by preserved ICA blood flow with half-squats that also may explain maintained mental arousal, concentration, and feelings of fatigue. These data offer potential mechanistic insight into how cognition is preserved during long sitting.”
The researchers note some of their study’s limitations. Namely, participants in the control group were asked “not to move their legs or fidget,” which doesn’t represent a real-world situation. While it more effectively isolated the effect of the control and intervention conditions on participants, it may have limited the study’s validity. Further, they only tested one domain of cognitive function using two tests; it’s possible that other domains, such as attention, memory, and decision-making, may be affected by prolonged sitting. Future studies are needed to assess whether they are.
Nonetheless, the researchers say that this easy-to-do exercise may provide some benefits.
“The current findings suggest that half-squat exercises, a simple and highly feasible exercise strategy, can improve some aspects of executive function and suppress fatigue increases which maintaining ICA flow during acute bouts of prolonged sitting compared to uninterrupted sitting,” the researchers said.
The study was published in the journal Applied Physiology.
Source: American Physiological Society