This study aims to elucidate the analgesic effects of TENS on shoulder MEP and to determine whether factors such as pain phenotype, psychological characteristics, and stimulation parameters influence these effects in a preliminary setting.
A randomized crossover design was employed in this study. Seven people with chronic shoulder pain participated and received three types of TENS interventions: high-frequency TENS (HF-TENS), low-frequency TENS (LF-TENS), and placebo TENS (P-TENS). Baseline assessments included quantitative sensory testing (QST), the state-trait anxiety inventory, and heart rate variability (HRV) measurements. TENS was administered for 30 minutes, and shoulder MEP along with QST were measured at three time points: baseline, 20 minutes after the start of TENS, and at the end of the TENS administration. Shoulder MEP was assessed using a Numerical Rating Scale (NRS) during shoulder flexion, and an accelerometer was used to ensure consistent shoulder movement across all measurement time points. NRS scores were analyzed using ANOVA with bonferroni correction for multiple comparisons.
NRS scores in the HF-TENS group was significantly lower than in the P-TENS group at 20 minutes (p = 0.03). The effectiveness of TENS tended to be reduced in participants with lower HRV and higher anxiety scores.
HF-TENS may reduce MEP in individuals with chronic shoulder pain. However, the sample size needs to be increased, and further investigations are warranted to confirm these findings.
TENS administration may potentially assist individuals with chronic shoulder pain in alleviating MEP, providing a non-invasive option for pain management and enhancing their capacity for physical activity.
Pain
Shoulder
