Task-dependent muscle activation during functional upper-Limb tasks in adults with and without chronic non-specific neck pain: A cross-sectional study

BackgroundAlthough many studies explore surface electromyography (sEMG) in static postures, research on muscle activation during dynamic tasks in chronic non-specific neck pain (CNNP) is limited.ObjectivesTo compare trapezius and sternocleidomastoid (SCM) activation and functional capacity during five upper limb tasks between individuals with CNNP and asymptomatic controls.MethodsThis was a cross-sectional comparative observational study. Twenty-seven individuals with CNNP and 25 asymptomatic controls completed five tasks: repetitive reaching (RRT), sustained overhead work (OW), waist-to-overhead lift (OL), fingertip dexterity (FD), and hand-forearm dexterity (HFD). sEMG recorded upper (UT), middle (MT), and lower trapezius (LT), and SCM activity. Functional capacity was assessed using selected WorkWell Systems Functional Capacity Evaluation (WWS-FCE) tasks.ResultsCNNP individuals showed greater UT activation across all tasks (p < 0.01, d = 0.78-1.67) and significant MT differences in most conditions (p < 0.01, d = 0.84-1.44). LT showed smaller but significant differences (p < 0.05, d = 0.47-0.84). SCM activity increased during OL (p < 0.01, d = 0.73-1.08) and in one RRT subtask (p = 0.011, d = 0.73). CNNP performed worse than controls in RRT (p < 0.001, d = -1.32 to -1.61), OW (p < 0.001, d = -2.17), OL (p = 0.006-<0.001, d = -0.80 to -1.26), and HFD (p < 0.001, d = -1.06 to -1.36), with no significant FD differences (p > 0.05). Significant Group × Task interactions were observed for UT, MT, and SCM (p < 0.05).ConclusionMuscle activation profiles in chronic non-specific neck pain change with tasks, highlighting the importance of evaluating functional activities beyond static-posture assessments.