This study had the objectives of investigating the effect of spray and stretch (SS) versus control on reducing post-needling soreness of one latent myofascial trigger point (MTrP) and if elevated levels of psychological distress are associated with increased post-needling pain intensity. A 72-hour follow-up, single-blind randomized controlled trial consisting of healthy volunteers (N=70:40 men,30 women) aged 18 to 36 years (mean±SD, 21±4y) with latent MTrP in one upper trapezius muscle was conducted. All subjects were given a dry needling application over the upper trapezius muscle. Then, participants were seperated at random into two groups: an intervention group, which received SS over the needled trapezius muscle, and a control group that did not receive any intervention. The primary outcome measures were the visual analog scale (VAS; at post-needling, post-treatment, 6, 12, 24, 48 and 72 hours), pressure pain threshold (PPT; at pre-needling, post-needling, 24 and 48 hours). Psychological distress was evaluated by the Symptom Checklist-90-Revised. Repeated measures analysis of variance (ANOVA) showed a significant interaction between group and time (F3,204.8=3.19, P.05). Repeated measures of covariance (ANCOVA) showed that none of the psychological covariates affected these results. Somatization, anxiety, interpersonal sensitivity and hostility were significantly correlated (P<.05) with post-needling pain intensity. Repeated measures ANOVA did not show a significant effect of SS on mechanical hiperalgesia (F2.6,175=1.9, P=.131, ηp2=0.02).
The study found the SS to have a short-term (less than 6 hours) effect reducing post-needling soreness of a latent MTrP. PPT did not significantly change after SS. Psychological factors are associated with post-needling pain.