Effects of Strength Training on Neck Muscle Function and Tenderness in Patients with Chronic Headache: A Secondary Analysis of a Clinical Trial

<b>Background/Objectives</b>: This study presents a secondary analysis from a previously published trial on strength training and postural correction in chronic headache patients. Here, we investigate changes in neck muscle function and tenderness, and their relationship with headache symptoms. <b>Methods</b>: A total of 22 headache patients from a single-arm open-label trial were included in this study to assess muscle function and tenderness. The maximum voluntary contraction of neck flexion and extension, shoulder elevation, and craniocervical flexion test were performed at baseline, week eight, and week 14. The extension/flexion ratio of the neck, the rate of force development, and the early rate of force development for shoulder elevation were calculated. Muscle tenderness was analyzed using the total tenderness score (TTS) and correlations between these outcomes and headache changes were explored. <b>Results</b>: After the intervention muscle tenderness significantly decreased (-5.6 ± 6.4; <i>p</i> < 0.001) and significant improvements in muscle function were observed. Correlations of muscle function showed a significant and moderate correlation between TTS and extension/flexion ratio (Spearman rho: 0.567, <i>p</i> = 0.014). <b>Conclusions</b>: The results indicate that strength training and postural correction improve muscle function and reduce pericranial tenderness in patients with chronic headaches. These findings suggest that muscle tenderness and extension/flexion ratio may be useful for monitoring exercise interventions focused on improving the strength and balance of the neck in patients with chronic headaches.