Three weeks of interrupting sitting lowers fasting glucose and glycemic variability, but not glucose tolerance, in free-living women and men with obesity

OBJECTIVE To determine whether interrupting prolonged sitting improves glycemic control and the metabolic profile of free-living adults with obesity. METHODS Sixteen sedentary individuals (10 women/6 men; median [IQR] age 50 [44-53] years, BMI 32 [32-35.8] kg/m2) were fitted with continuous glucose and activity monitors for 4 weeks. After a 1-week baseline period, participants were randomized into habitual lifestyle (Control) or Frequent Activity Breaks from Sitting (FABS) intervention groups. Each day, between 0800-1800 h, FABS received smartwatch notifications to break sitting with 3 min of low-to-moderate-intensity physical activity every 30 min. Glycemic control was assessed by OGTT and continuous glucose monitoring. Blood samples and vastus lateralis biopsies were taken for assessment of clinical chemistry and the skeletal muscle lipidome, respectively. RESULTS Compared to baseline, FABS increased median steps by 744 (IQR [483-951]) and walking time by 10.4 (IQR [2.2-24.6]) min per day. Other indices of activity/sedentary behavior were unchanged. Glucose tolerance and average 24-h glucose curves were also unaffected. However, mean (±SD) fasting glucose levels (-0.34 [±0.37] mmol/L) and daily glucose variation (%CV; -2 [±2.2]%) reduced in FABS, suggesting a modest benefit for glycemic control that was most robust at higher volumes of daily activity. Clinical chemistry and the skeletal muscle lipidome were largely unperturbed, although 2 long-chain triglycerides increased 1.25-fold in FABS, post-intervention. All parameters remained stable in Control. CONCLUSIONS Under free-living conditions, FABS lowered fasting glucose and glucose variability. Larger volumes of activity breaks from sitting may be required to promote greater health benefits.