Increased Upper and Lower Trapezius Muscle Activities During Rest in Side-Lying Position in Young Adults with Forward Head Posture

Abstract

Forward head posture (FHP) is a problem with muscle imbalance around neck and shoulder girdle. The FHP might be a silent threat for young adults in their later stages of life. An impact of the FHP on muscle activities in upright posture has been well established; however, how it influences neck and shoulder muscle activities in side lying-position has been still elusive. This study was aimed to investigate electrical muscle activities (% maximum voluntary contraction, %MVC) on both upper and lower sides of 4 neck and shoulder muscles—sternocleidomastoid (SCM), upper trapezius (UT), middle trapezius (MT) and lower trapezius (LT) using surface electromyography (EMG) in 34 participants (normal head posture (NHP) group, aged 21.24±0.97 years old, n=17; and FHP group, aged 20.83±1.20 years old, n=17). Each participant performed side-lying position with a self-selected pillow for 5-min of acclimatization and another 12-min for EMG recordings. Results showed that there was no significant difference between %MVC on upper and lower sides of all muscles in both groups. In contrast, the %MVC of the trapezius muscles on the upper side of the FHP group were significantly higher than the NHP group i.e., 1.26±0.76 vs 0.79±0.44 in UT; and 3.06±1.86 vs 1.74±1.14 in LT, respectively. Despite symmetrical activation of bilateral muscles can be seen in both groups; however, the FHP could induce over activation of UT and LT while resting in side-sleeping position. Therefore, selective technique to minimize muscle activation during resting position might be required as preventive regimen for this group of young adults