Effects of specific extensor exercise on balance control in patients with neck pain; a randomized controlled trial

Neck pain can disrupt the somatosensory system, impairing balance control and neck muscle function. Deep cervical extensor muscles maintain cervical postural alignment and intersegmental stability; however, its effects on balance remain unclear. This study determined the effects of specific deep neck extensor training (SpecExtTx) compared with proprioceptive training (PropTx), balance training (BalanceTx), and control (CG) on balance control, deep cervical muscle cross-sectional area (CSA), pain-related outcomes, and cervical joint position sense (CJPS). A total of 132 participants with chronic subclinical neck pain were randomly assigned to one of four groups: SpecExtTx, PropTx, BalanceTx, or CG. Outcome measures included the Balance Error Scoring System Thai version (BESS-TH), Timed Up and Go test (TUG), Visual Analog Scale (VAS), Neck Disability Index Thai version (NDI-TH), CSA, and CJPS. Assessments were conducted at baseline, immediately post-intervention (6 weeks intervention), and at 1-month follow-up using two-way repeated measures analysis of variance (ANOVA) for analysis of within-group differences and univariate analysis of covariance (ANCOVA) (adjusted for baseline) for between-group differences. SpecExtTx group demonstrated less improvement, showing significantly smaller BESS-TH score reductions than the BalanceTx group at both time points (p = 0.02–0.03, mean difference (MDs) = 3.16 to 3.43, effect size (ES) = 0.70 to 0.73. TUG had no improvement between groups at both time points. SpecExtTx demonstrated significantly improved VAS score than the other three groups at post-intervention (p < 0.05; MDs = -1.10 to -0.87, ES = -0.88 to -0.69) and greater CG at follow-up (p < 0.05; MD = -1.06; ES = -0.75). SpecExtTx group had more improvement in the NDI-TH scores than the BalanceTx group in post-treatment (p = 0.04, MD = -1.96, ES = -0.68). SpecExtTx group had greater CSA increase compared to the other groups at both time points (p < 0.05; MDs = 0.19 to 0.23; ES = 1.41 to 2.19). SpecExtTx group demonstrated significantly better CJPS than the CG in the extension direction at post-treatment (p = 0.02, MDs = -0.73, ES = -0.76. Specific deep cervical extensor training demonstrated effects on balance similar to balance training; however, it was inferior to BalanceTx effects. Nevertheless, SpecExtTx also improved proprioception and muscle size while reducing pain and disability in neck pain populations. The trial was also registered in the Thai Clinical Trial registry (TCTR20230831002) and registered on 31 August 2023.