Free-living muscle activity in type 2 diabetes across whole-of-day, sitting, standing, and walking

In adults with type 2 diabetes, we used thigh-worn accelerometers and electromyographic (EMG) shorts to investigate muscle activity in a free-living environment. Quadriceps, hamstring, and gluteal muscle EMG was normalized individually to that during isometric maximal voluntary contraction (%EMG_MVC). Devices were worn concurrently by 18 participants (11 female) for an average of 3.2 days. Median EMG amplitude (aEMG) was assessed from all three muscle groups during the whole day and within accelerometer-derived sitting, standing, and walking time. Associations of muscle activity with the duration of these behaviours were explored via multiple linear regression adjusting for sex, age, body composition, and diabetes duration. Free-living aEMG for the whole day was 3.3%EMG_MVC (range 1.6%-6.2%), for sitting 2.5%EMG_MVC (1.8%-3.7%), for standing 6.3%EMG_MVC (3.8%-19.8%), and for walking 19.8%EMG_MVC (7.5%-34.1%). The aEMG varied between muscle groups, being generally higher in gluteal and hamstrings than quadriceps. Both sitting, standing, and walking aEMG in the hamstrings was positively associated with whole day aEMG. Furthermore, sitting aEMG in the hamstrings was inversely associated with sitting duration, and standing aEMG in the hamstrings with walking duration. People with type 2 diabetes have low overall muscle activity during daily living. Walking time may be an effective countermeasure against low daily muscle activity. High individual variability highlights potential to personalize recommendations on sitting, standing, and walking. Notably, the ability to activate hamstrings during these activities may support shorter sitting and longer walking durations in daily life.