When We Sit: Textile Electromyography Identifies Decreasing Muscle Activity and Implications for Metabolic Health

Prolonged sitting is ubiquitous and increases risk of diabetes, heart disease and some cancers. A suspected mechanism behind the adverse cardiometabolic effects of prolonged sitting is high prevalence of muscle inactivity. Understanding muscle activity when we sit may be crucial for developing effective interventions. Using fabric-embedded wearable electrodes (electromyography; EMG), the activity of muscles can be directly examined when we sit. We examined muscle activity during 7,684 sitting bouts in daily living using EMG shorts in 84 adults from three separate cohorts (46% female; mean age (SD): 43.7yr (18.7yr). When we sit, thigh muscle activity decreases, but sitting bouts that are preceded by more-intense and longer-duration physical activity show more sustained persistence of muscle activity. More frequent and intense interruptions to sitting result in 5 extra minutes of muscle activity per hour of sitting time. These findings provide new insights into the metabolic health risks of prolonged sitting and suggest practical ways to counteract them.