Muscle states exhibited distinct regional and temporal patterns during supine sleep, with statistically significant negative correlations identified between muscle fatigue and regional interface pressure, most strongly between gluteus medius fatigue and hips pressure distribution (Kendall's τ = -0.723, p < 0.01), suggesting that reduced interface pressure in partially suspended body regions elicits compensatory muscle activation leading to fatigue accumulation.
Trapezius muscle activity remained stable in recovery or force decrease states throughout three hours of supine sleep.
Erector spinae muscle progressively shifted toward fatigue over the three-hour supine sleep period.
Gluteus medius transitioned from fatigue toward recovery during the three-hour supine posture.
Biceps femoris showed increasing fatigue over the three-hour supine sleep monitoring period.
Interface pressure was highest at the shoulder and hip regions during supine posture.
Statistically significant negative correlations were identified between muscle fatigue states and regional interface pressure.
Reduced interface pressure in partially suspended body regions appears to elicit compensatory muscle activation leading to fatigue accumulation.
The JASA method effectively discriminated muscle states during prolonged supine posture.
This research suggests that during three hours of lying still on your back (as during sleep), different muscles in your body experience very different patterns of fatigue and recovery. By simultaneously measuring muscle electrical activity from four muscle groups (trapezius in the upper back, erector spinae along the spine, gluteus medius in the hip, and biceps femoris in the back of the thigh) and the pressure between the body and mattress surface, researchers found that some muscles progressively fatigue while others recover — and that how much pressure a body region experiences is closely linked to how fatigued those nearby muscles become. One of the key findings is that body regions that are 'partially suspended' — meaning they don't make much contact with the mattress and therefore have low interface pressure — appear to require more muscle effort to maintain position, leading to fatigue buildup. The strongest relationship found was between the hip muscles (gluteus medius) and hip pressure, where lower pressure corresponded with greater fatigue. This suggests that mattress designs that fail to adequately support certain body areas may inadvertently cause muscle strain even during sleep. This research matters because it provides a scientific framework for understanding why people may wake up sore or unrested even after a full night's sleep. The findings suggest that mattresses or sleep systems that can dynamically adjust pressure distribution in real time — targeting under-supported regions — could potentially reduce muscle fatigue and improve sleep quality and recovery. The study used only ten healthy adults in a controlled laboratory setting over three hours, so further research with larger, more diverse populations over full sleep periods would be needed to confirm and extend these findings.
Zhang T, Li X, Ding L, Huang Y, Chen W, Yao F, et al.. (2026). A biomechanical monitoring framework for supine sleep: continuous muscle state assessment using sEMG-JASA synchronized with interface pressure mapping.. Medical engineering & physics. https://doi.org/10.1088/1873-4030/ae52fc