The aim of this study was to evaluate the effects of pulsed electromagnetic field (PEMF) and exercises in reducing pain and improving function and muscle strength in people with shoulder impingement syndrome (SIS). The authors conducted a double-blind randomized clinical trial, with a 3 month post-treatment follow-up of fifty-six patients between 40 and 60 years old, with a diagnosis of SIS, who were assigned active PEMF (n = 26; mean age, 50.1 years) or placebo PEMF (n = 30; mean age, 50.8 years old) at random. Following 3 weeks of active or placebo PEMF, both groups performed the same program of exercises that focused on shoulder strengthening. A visual analogue scale (VAS), the University of California/Los Angeles (UCLA) shoulder rating scale, the Constant-Murley shoulder score, and the hand-held dynamometry for muscle strength were used as outcome measures at baseline (pretreatment), at 3 weeks (post active or placebo PEMF), at 9 weeks (post-exercises), and at 3 months post-treatment. The patients in the active PEMF group had a higher level of function and less pain at all follow-up timeframes compared to baseline (P<.05). On the other hand, the placebo PEMF group showed increased function and reduced pain only at 9 weeks and 3 months follow-ups (P<.05), i.e., after performing the associated to exercises. For the shoulder dynamometry, the active PEMF group had increased strength for lateral rotation at 9 weeks (P<.05) and medial rotation at 9 weeks and 3 months (both, P<.05) when compared to baseline. They did not find any difference for shoulder strength in the placebo PEMF group (P>.05), as well as the analysis between-groups (P>.05) for all outcome measures.
The study found that when combined PEMF and shoulder exercises are effective in improving function and muscle strength and reducing pain in patients with SIS. The authors note though that their results should be carefully interpreted because of the lack of differences between groups.