Interrupting prolonged sitting with repeated chair stands or short walks reduces postprandial insulinemia in healthy adults.
Level 2 - randomized trial
Randomized crossover trial
PubMed 33180640 · doi:10.1152/japplphysiol.00796.2020
What was done
Fourteen healthy adults (7 males, 7 females; age 24 ± 5 years; BMI 25 ± 5 kg/m2; 40 ± 8 mL/kg/min; 7,033 ± 2,288 steps/day) completed three 7.5-hour trials in randomized order: uninterrupted sitting (SIT), sitting with 2-minute walks at 3.1 mph every 30 minutes (WALK), and sitting with 15 chair stands with calf raises every 30 minutes (SQUAT). Participants consumed mixed-macronutrient liquid meals for breakfast (20% of daily energy) and lunch (30% of daily energy). Blood samples were analyzed for postprandial plasma glucose and insulin, and skeletal muscle biopsies were evaluated for glucose uptake signaling markers (AKT Thr308, AKT Ser473, and AS160 Ser318).
What was found
Following breakfast, postprandial glucose and insulin concentrations did not differ across conditions. Following lunch, peak insulin concentration was 52 ± 27 µIU/mL in SQUAT (P < 0.01) and 62 ± 35 µIU/mL in WALK (P < 0.05) compared with 79 ± 43 µIU/mL in SIT. The 1-hour post-lunch insulin incremental area under the curve (iAUC) was reduced by 37% in SQUAT (P < 0.01) and 29% in WALK (P < 0.05) versus SIT. The 3-hour insulin iAUC was reduced by 24% in SQUAT only (P < 0.05 vs. SIT). The 3-hour insulin:glucose iAUC was reduced by 30% in SQUAT and 23% in WALK versus SIT (P < 0.05). Phosphorylation of AKT Thr308, AKT Ser473, and AS160 Ser318 showed no significant differences between conditions (P > 0.05).
Why it matters
Simple, equipment-free body-weight exercises like chair stands provide an effective alternative to walking breaks for blunting postprandial insulin spikes during prolonged sitting.
Limits
The sample size was small (n = 14) and limited to young, healthy, active adults. The protocol tested an acute 7.5-hour single-day intervention using liquid meals, so long-term metabolic adaptations and responses to solid mixed meals remain unmeasured. Muscle biopsy signaling markers did not detect the mechanism explaining the reduced insulinemia.