The Impact of Hunched Posture on the Elasticity of the Upper and Middle Trapezius Muscles During Sedentary Activity.

Abstract

Prolonged sitting is often associated with poor posture, hunched shoulder posture (HSP), which may alter the mechanical properties of key muscles such as the upper trapezius (UT) and middle trapezius (MT). This study aimed to investigate the effect of HSP on the elasticity of the UT and MT muscles during a sitting task and to gain insight into the musculoskeletal risks associated with postural errors while sitting. Thirty-four asymptomatic individuals participated in this study between the ages of 25 and 40, who led sedentary lifestyles with 7 h of sedentary activity per day. None of the participants had a history of neurological, systemic, or musculoskeletal diseases that may affect muscle function. The MyotonPRO device was used to measure UT and MT muscle elasticity during normal shoulder posture (NSP) and HSP. Statistical analyses were performed to compare the mechanical properties of the UT and MT muscles across the different postural groups. The findings revealed that the mean elasticity of the UT increased from 1.25 (±0.30) under NSP to 1.30 (±0.32) under HSP. The MT exhibited a more pronounced change, with mean elasticity rising from 1.73 (±0.30) under NSP to 2.12 (±0.34) under HSP. These results indicate significant adaptations in muscle elasticity due to poor postural alignment, suggesting a compensatory response to the mechanical demands of HSP (p < 0.001). The study highlights the detrimental effects of hunched posture on the mechanical properties of the upper and MT muscles, emphasizing the need for ergonomic interventions to promote better postural alignment among sedentary workers. Regular breaks and exercises aimed at improving posture are recommended to mitigate the risks associated with prolonged poor posture, ultimately enhancing worker well-being and productivity.