Substituting Sitting With Standing and Walking in Free-living Conditions Improves Daily Glucose Profile in South Asians

Anthropometric measurement tools, including a stadiometer, a measurement tape and a digital weighing scale, an activity monitor and a Flash Glucose Monitor and sensor, were posted to the participants' home or workplace or the research team dropped all these items at participants' doorstep to allow participants to take their measures including height, weight, and waist circumference.

Participants performed a try-out day of the SITless regimen after preliminary testing and before the first experimental regimen. Participants were only eligible for inclusion if they were able to adhere to the experimental protocol (i.e., substitute a minimum of 5-h/day sitting with ≥2-h of self-perceived light walking and ≥3-h of standing), assessed via monitoring with an activPAL. Participants were provided with a second attempt if required.

After the try-out day, participants were set up with the FGM and activPAL, which were both worn throughout the experimental period. Setup was completed 24-h before the commencement of the first experimental regimen and subsequently worn for 11 days (i.e., 2* 4-day regimens and 3 days washout). Regimen 1 (SIT or SITless) took place over 4 days (day 1-4: Monday to Thursday), followed by a 3-day washout period (day 5-7: Friday to Sunday), followed by regimen 2 (SIT or SITless) for 4 days (day 8-11: Monday to Thursday). Participants were informed of the order of their experimental regimens and provided verbal and written guidance on how to complete the protocols. The experimental regimens were as follows:

• SIT regimen: Participants were instructed to restrict walking to ≤1 h/day and standing to ≤1 h/day during their waking day. Participants were allowed to perform their daily activities, including cooking and other household activities, within the 2-h of permitted walking and standing.
• SITless regimen: Participants were instructed to substitute a minimum of 5-h/day sitting with ≥3-h of standing and ≥2-h of self-perceived LPA in addition to interrupting their sitting for 2-5-min every 30-min. A list of activities (including walking at a slow pace, walking on the spot, jumping up and down, and standing) was provided as examples of activities that participants could perform during this regimen. Participants received feedback on their non-sitting time and the number of light and moderate-intensity steps from the try-out day. They were guided towards achieving compliance in this regimen by identifying potential activities they could engage in to interrupt sitting, reviewing their number of sitting interruptions and aiming to accumulate approximately 12,000 steps per day (6,000 steps being equivalent to 1-h of moderate-intensity walking).

Participants were asked to refrain from food and drink containing alcohol for 24-h before and to avoid performing structured exercise for 48-h before the experimental protocol commenced and throughout the entire experimental period (a total of 11-days). A kitchen scale was provided so participants could weigh and record all food and beverage consumption in a diary during the first 4-day regimen and replicate this dietary intake exactly during the second 4-day regimen. Participants were instructed to consume a standardised diet (at least 50% carbohydrate) in order to reduce dietary heterogeneity within the study population. Participants were advised that the meals were spaced evenly throughout the day with 3 to 4-h intervals, with snacks consumed between meals to ensure three distinct and consistent glucose responses across each day.

Inclusion criteria

• Self-identified South Asian ethnicity.
• Self-report sitting at least 7 hours per day.
• Overweight or obese (BMI>23.0 kg/m2)

Exclusion criteria

• Unable to speak and read English.
• Not able to perform light-intensity activities.
• Diagnosed cardiovascular disease or diabetes.