Influence of forward head posture on muscle activation pattern of the trapezius pars descendens muscle in young adults

Abstract

Forward head posture (FHP) is a serious problem causing head and neck disability, but the characteristics of muscle activity during long-term postural maintenance are unclear. This study aimed to investigate a comparison of electromyography (EMG) activation properties and subjective fatigue between young adults with and without habitual FHP. In this study, we examined the changes in the spatial and temporal distribution patterns of muscle activity using high-density surface EMG (HD-SEMG) in addition to mean frequency, a conventional measure of muscle fatigue. Nineteen male participants were included in the study (FHP group (n = 9; age = 22.3 ± 1.5 years) and normal group (n = 10; age = 22.5 ± 1.4 years)). Participants held three head positions (e.g., forward, backward, and neutral positions) for a total of 30 min each, and the EMG activity of the trapezius pars descendens muscle during posture maintenance was measured by HD-SEMG. The root mean square (RMS), the modified entropy, and the correlation coefficient were calculated. Additionally, the visual analogue scale (VAS) was evaluated to assess subjective fatigue. The RMS, VAS, modified entropy, and correlation coefficients were significantly higher in the FHP group than in the normal group (p < 0.001). With increasing postural maintenance time, the modified entropy and correlation coefficient values significantly decreased, and the mean frequency and VAS values significantly increased (p < 0.001). Furthermore, the forward position had significantly higher RMS, correlation coefficient, modified entropy, and VAS values than in the neutral position (p < 0.001). The HD-SEMG potential distribution patterns in the FHP group showed less heterogeneity and greater muscle activity in the entire muscle and subjective fatigue than those in the normal group. Excess muscle activity even in the neutral/comfortable position in the FHP group could potentially be a mechanism of neuromuscular conditions in this population.

Correlation between Forward Head Posture, Round Shoulder Posture, and Muscle Activity during the Shoulder Flexion and Abduction Task

“…[26][27][28]31 On the other hand, there was no difference in muscle activation during shoulder flexion and abduction according to low load because it already has increased activity of the UT, decreased activity of SA, and lower endurance in FHP. 30,31 Because of mild FHP, it is suggested that there might be no significant correlation between FHP and muscular activation in the present study. In addition, when the posture is stable, the muscle activity increased in the SA and pectoralis major as the load increased, but the UT showed constant muscle activity.…”

“…In previous studies reported that FHP changed according to the muscle length and muscle tension, such as sternocleidomastoid, neck extensor, trapezius, SA, and pectoralis. 7,[29][30][31] In FHP, increased muscle activation of the UT and decreased muscle activation of the SA were noted during shoulder flexion and abduction. [26][27][28]31 On the other hand, there was no difference in muscle activation during shoulder flexion and abduction according to low load because it already has increased activity of the UT, decreased activity of SA, and lower endurance in FHP.…”

Effects of Artificial Forward Head and Neck Posture on Shoulder Rotation Range and Strength in Healthy Individuals

“…15 People with FHP showed abnormal electromyographic (EMG) activity in the neck muscles, and it was reported that shoulder muscles, such as the serratus anterior and trapezius muscle, were also negatively affected. 12,16 Objective and quantitative clinical investigations are important in determining the precise diagnosis for patients with musculoskeletal dysfunctions, such as FHP and neck problems. 2,7 Many previous studies related to FHP and the kinesiologic function of the shoulder complex reported the effects of FHP on EMG activity of the shoulder muscles, such as the upper trapezius, serratus anterior, or lower trapezius.…”

“…2,7 Many previous studies related to FHP and the kinesiologic function of the shoulder complex reported the effects of FHP on EMG activity of the shoulder muscles, such as the upper trapezius, serratus anterior, or lower trapezius. 12,16 Although high-quality kinetic and kinematic evaluations, such as a 3D motion analysis and EMG devices, are used to investigate the relationship between FHP and shoulder dysfunction, most of the studies have mainly focused on shoulder muscle activity or neck pain. 2,3,16 In addition, studies verifying the effect of artificial FHP on the kinetics and kinematics of the shoulder joint using internal and external movement tasks are insufficient.…”

“…12,16 Although high-quality kinetic and kinematic evaluations, such as a 3D motion analysis and EMG devices, are used to investigate the relationship between FHP and shoulder dysfunction, most of the studies have mainly focused on shoulder muscle activity or neck pain. 2,3,16 In addition, studies verifying the effect of artificial FHP on the kinetics and kinematics of the shoulder joint using internal and external movement tasks are insufficient.…”