The Effects of Interrupting Prolonged Sitting With Bouts of Physical Activity on Neurocognitive Function in Obesity

It is projected that by 2030 almost 50% of adults in the USA will have obesity. High sedentariness and physical inactivity contribute to the obesity pandemic. Neurocognitive deficits compound the global burden of obesity. Specifically, adults with obesity underperform on tasks of executive functioning, which underpin goal-directed behavior and have been linked to occupational success. Growing evidence suggests poorer executive functioning among more sedentary adults. Emergent studies have shown that accumulating sedentary time in prolonged bouts (e.g., remaining sedentary continuously 20 min or more) may decrease the ability to control distractions along with working memory. Interrupting prolonged sitting with brief bouts of physical activity is an effective strategy to improve postprandial glucose metabolism. However, the effects of this simple intervention on neural processes supporting executive functioning remain unknown. Accordingly, the aim of this study is to test the effects of interrupting prolonged sitting with frequent (every 30 min) but brief (3 min) physical activity bouts on inhibitory control, working memory, and their neuroelectric indices (N2, P3a, and P3b components of event-related brain potentials). Our secondary aim is to explore the potential mechanisms underlying the effects of interrupting prolonged sitting with physical activity on cognitive and brain function through glucose metabolism and insulin physiology. Findings from this study will help advance our understanding of how restructuring sedentary time may help improve cognitive and brain functions among adults with obesity.

Measurements of cognitive and brain function will be taken before, and after three hours of prolonged sitting. Metabolic, heart rate, and blood pressure measures, along with the ratings of fatigue will be collected before and during the three-hour prolonged sitting time. The prolonged sitting time will be either interrupted with physical activity breaks or with sedentary breaks (attention control). Habitual physical activity, sedentary behavior, sleep, and dietary intake will also be assessed.

Eligibility Criteria:
Inclusion Criteria:

* • Informed consent

  * Age 21-64 years
  * BMI within ≥ 30 and \< 40 kg/m2 range
  * Pre-menopausal
  * Fasting plasma glucose (FPG) \< 100 mg/dL
  * Resting blood pressure: systolic \< 160 mmHg or diastolic \< 100 mmHg
  * Employed in sedentary occupation (i.e., participants reporting sitting on average 6 h/d on a weekday and with objectively assessed sitting time ≥ 8 h/day)
  * Physically inactive (i.e., engaging in \< 150 min of moderate or \< 75 min of vigorous or any combination of the two intensities per week)
  * Participants must have had no prior diagnosis of cognitive or physical disability (e.g., ADHD, severe asthma, epilepsy, chronic kidney disease, or dependence upon a wheelchair/walking aid)
  * Free of medication that could affect cognitive function or metabolism
  * Normal or corrected-to-normal vision based on the minimal 20/20 standard in order to complete the cognitive task (below 20/20 vision)
  * Must be able to engage in vigorous exercise
  * Fluency in English

Exclusion Criteria:

* • Impaired glucose tolerance defined as fasting plasma glucose (FPG) \< 100 mg/dL

  * Oral glucose tolerance test (OGTT) blood glucose values ≥ 200 mg/dL
  * Participants with any psychiatric, neurological or metabolic disorder
  * Participants who have or are currently taking the medication that could affect cognitive function, metabolism or weight status
  * Participants with substance abuse
  * Participants with a standardized score on the test of general cognitive abilities below 85
  * Participants with anemia
  * Pregnant women or those with a possible pregnancy
  * History of injury to the spinal cord