Publications

Objectives: To determine whether intramuscular electrical stimulation (IMES) added to a standardized home-exercise program is more effective than home exercise alone for short-duration myofascial shoulder pain, and to assess effects on disability, pressure pain threshold, tissue perfusion, muscle mechanical properties, and shoulder abductor strength.

Methods: In this single-centre, assessor-blinded, parallel-group randomized controlled trial, 50 adults with myofascial shoulder pain were allocated 1:1 to home exercise plus weekly IMES for 6 weeks or home exercise alone. Outcomes were assessed at baseline, post-treatment, and 4-week follow-up. The primary outcome was pain intensity (NRS). Secondary outcomes were DASH, pressure pain threshold, tissue perfusion, muscle tone, stiffness, and maximum voluntary contraction.

Results: IMES produced greater improvement in pain than exercise alone at post-treatment (ΔΔ −2.50 NRS points, 95% CI −3.05 to −1.94; p < 0.001; g=−3.25) and follow-up (ΔΔ −2.12, 95% CI −2.63 to −1.60; p < 0.001; g=−2.75). Disability also improved more with IMES (DASH: ΔΔ −16.28 and −21.97 points, both p < 0.001). IMES additionally improved pressure pain threshold, tissue perfusion, muscle tone, and stiffness (all p < 0.001), but not shoulder abductor strength (interaction p = 0.106). An exploratory pooled correlation was observed between increased perfusion and greater pain reduction (r=−0.87, p < 0.001), but this association should be interpreted cautiously. Minor adverse events occurred only in the IMES group.

Conclusions: IMES was associated with short-term improvement in pain, disability, and physiological measures when added to home exercise in myofascial shoulder pain, but these findings require cautious interpretation and further confirmation because the study lacked a sham comparator, participant blinding was not feasible, and subjective outcomes may have been influenced by non-specific treatment effects.

Keywords: myofascial trigger points, muscle stiffness, tissue perfusion, myotonometry, maximum voluntary contraction, shoulder pain, microcirculation, electrostimulation

In patients with myofascial shoulder pain, intramuscular electrical stimulation combined with home exercise was associated with greater short-term and early follow-up improvements in pain intensity, upper-limb disability, pressure pain threshold, tissue perfusion, muscle tone, and muscle stiffness than home exercise alone, whereas shoulder abductor strength did not differ between groups. However, the magnitude of effect is uncertain and may have been overestimated because of baseline imbalances, low baseline variability, and the small sample size. The observed association between improved perfusion and pain reduction is exploratory only and should not be interpreted as evidence of a causal mechanistic pathway. Moreover, because PPT and perfusion were not assessed at a distant unaffected control site, these physiological findings apply to the assessed trigger-point regions and do not establish local specificity. In addition, because the study lacked a sham comparator and participant blinding was not feasible, any apparent benefits in subjective outcomes may reflect a combination of specific and non-specific treatment effects. These findings support IMES as an adjunctive option for short-term symptom improvement only, with effects that are auspicious but require confirmation in larger, sham-controlled trials, rather than a definitive stand-alone treatment.