Overview

Rationale: Sedentary behavior (SB) has been associated with impaired cognitive function in elderly, and negatively impacts glucose metabolism. Interrupting sitting with physical activity (PA) bouts may exert beneficial effects on cognitive function via an improved glucose metabolism. Nevertheless, the impact of breaking up prolonged sitting with various frequencies of PA bouts remains unexplored in young sedentary adults. Moreover, we hypothesize that the pattern of the breaks modifies the effects. Thus, randomized controlled trials (RCTs) are highly needed to investigate the effects of interrupting sitting with different frequencies of PA on cognitive function and glucose metabolism. We now hypothesize that interrupting sitting with different frequencies of walking breaks differentially affects cognitive function and glucose metabolism.

Objective: The aim is to investigate the effects of breaking up sitting with different frequencies of PA bouts on cognitive function and glucose metabolism in young sedentary adults.

Study design: A randomised, controlled cross-over study will be performed, consisting of four interventions in a counterbalanced order: uninterrupted prolonged sitting, short breaks, moderate breaks, and long breaks.

Intervention: Participants will complete four conditions in a randomized, counterbalanced order: sitting (uninterrupted prolonged sitting without any interruptions), short breaks (walk 1 minute every 10 minutes), moderate breaks (walk 3 minutes every 30 minutes), and long breaks (walk 27 minutes during the intervention). Each condition lasts 4.5 hours.

Eligibility

Inclusion Criteria:

• Men and women aged 18-35 years;
• BMI between 18.5-24.9 kg/m2;
• SB, i.e. sitting for an average of at least 9 hours per day;
• Physically inactive, i.e. engaging in exercise for less than 2 to 3 times per week;
• Stable body weight (weight gain or loss < 3 kg in the past three months);
• Willingness to engage in four 6-hour laboratory visits;
• No difficult cannulation.

Exclusion Criteria:

• Not sedentary, i.e. sitting for less than an average of 9 hours per day;
• Physically active, i.e. engaging in exercise for more than 3 times a week;
• Abuse of drugs;
• Use medication to treat BP, lipid, or glucose metabolism;
• Pregnant females.