Experimentally induced neck pain causes a decrease in thoracic but not lumbar spine stability

Exploring how metronome pacing at varying movement speeds influences local dynamic stability and coordination variability of lumbar spine motion during repetitive lifting

Auditory metronomes have been used to preserve movement consistency when examining local dynamic stability (LDS) and coordination variability (CV) of lumbar spine motion during repetitive movements. However, the potential influence of the metronome itself on these outcome measures has rarely been considered. Therefore, this study investigated the influence of different metronome paces (i.e., lifting speeds) on measures of lumbar spine LDS and thorax-pelvis CV during a repetitive lifting/lowering task in comparison to self-paced movements. Ten participants completed 5 repetitive lift/lower trials, where participants completed 35 consecutive repetitions (analysis on last 30 repetitions) at a self-selected pace for the first and last trial, and were paced by a 10 lift/min, 15 lift/min, and 20 lift/min metronome, in randomized order, for the remaining three trials. The average self-paced lift/lower speed before and after experiencing the three different metronome paced speeds was 16.2 (±1.02) and 17.2 (±0.73) lifts/min, respectively, and the most-preferred metronome pace trial was 15 lifts/min. Thorax-pelvis CV during the self-paced trials were similar (p > 0.05) to the 15 lift/min metronome paced trials, while greater thorax-pelvis CV was observed for the 10 lift/min compared to the 15 lift/min and 20 lift/min and second self-paced trial (all p < 0.026). This movement speed effect was not observed for lumbar spine LDS; however, more-dynamically stable movements were observed during all metronome paced trials in comparison to the self-paced trials. This study highlights that careful consideration is required when employing a metronome to control/manipulate movement characteristics while examining neuromuscular control using non-linear dynamical systems measures.

Segmental Chiropractic Spinal Manipulation Does not Reduce Pain Amplification and the Associated Pain-Related Brain Activity in a Capsaicin-Heat Pain Model

Musculoskeletal injuries lead to sensitization of nociceptors and primary hyperalgesia (hypersensitivity to painful stimuli). This occurs with back injuries, which are associated with acute pain and increased pain sensitivity at the site of injury. In some cases, back pain persists and leads to central sensitization and chronic pain. Thus, reducing primary hyperalgesia to prevent central sensitization may limit the transition from acute to chronic back pain. It has been shown that spinal manipulation (SM) reduces experimental and clinical pain, but the effect of SM on primary hyperalgesia and hypersensitivity to painful stimuli remains unclear. The goal of the present study was to investigate the effect of SM on pain hypersensitivity using a capsaicin-heat pain model. Laser stimulation was used to evoke heat pain and the associated brain activity, which were measured to assess their modulation by SM. Eighty healthy participants were recruited and randomly assigned to one of the four experimental groups: inert cream and no intervention; capsaicin cream and no intervention; capsaicin cream and SM at T7; capsaicin cream and placebo. Inert or capsaicin cream (1%) was applied to the T9 area. SM or placebo were performed 25 min after cream application. A series of laser stimuli were delivered on the area of cream application (1) before cream application, (2) after cream application but before SM or placebo, and (3) after SM or placebo. Capsaicin cream induced a significant increase in laser pain (p < 0.001) and laser-evoked potential amplitude (p < 0.001). However, SM did not decrease the amplification of laser pain or laser-evoked potentials by capsaicin. These results indicate that segmental SM does not reduce pain hypersensitivity and the associated pain-related brain activity in a capsaicin-heat pain model.

Is the pain pressure threshold linked to the transversus abdominis in women with chronic neck pain?: a preliminary report

PURPOSE

The present study aimed to investigate the relationship between the ultrasonography parameters of transversus abdominis and neck pain manifestations in women with chronic neck pain.

MATERIALS AND METHODS

Thirty women (mean age: 38.44 ± 9.56 years, BMI: 25.57 ± 3.32 kg/m²) with chronic neck pain were included in the study. The pain severity, disability scores, and bilateral pain pressure threshold of upper trapezius were assessed. The thickness of transversus abdominis in-rest and abdominal draw-in conditions were evaluated by two-dimensional ultrasonography. Pearson's correlation coefficients and linear regression statistics were determined.

RESULTS

We found a moderate correlation between the thickness of transversus abdominis in abdominal draw-in and the pain pressure threshold of right (r = 0.636, p < 0.001), and left upper trapezius (r = 0.403, p = 0.03). Moreover, there was a moderate correlation between the pain pressure threshold of the right upper trapezius and the thickness of transversus abdominis in-rest (r = 0.498, p = 0.006). No significant correlation was found between pain intensity, disability scores, and ultrasonography parameters of transversus abdominis. There was also a significant total effect of transversus abdominis' thickness on abdominal draw-in manoeuvre on predicting pain pressure threshold of right upper trapezius (B = 0.636, SE = 0.765, p < 0.001) and pain pressure threshold of left upper trapezius (B = 0.403, SE = 0.840, p = 0.03).

CONCLUSIONS

Our results revealed that upper trapezius muscle tenderness may associated with decreased muscle thickness of transversus abdominis. Addressing new exercise methodologies including transversus abdominis training in the management of chronic neck pain may be helpful to improve neck pain symptoms.