The Effects of Functional Magnetic Stimulation on Rectus Abdominis Muscle Size and Abdominal Subcutaneous Adipose Tissue Thickness

Background Functional magnetic stimulation (FMS) is a non-invasive technology that induces supramaximal muscle contractions through rapidly changing magnetic fields. It has been proposed as a method to enhance muscle hypertrophy and reduce localized adiposity, but objective clinical evidence remains limited. This pilot case series implemented a systematic intervention and measurement protocol to evaluate the effects of FMS on rectus abdominis muscle thickness and abdominal subcutaneous adipose tissue. Methods Ten healthy adults (six female, four male; mean age 32.7 years) underwent 10 sessions of abdominal FMS over three weeks using the Tesla Former® device (Iskra Medical, Otoče, Slovenia). Waist circumference and body weight were measured at baseline and at post-treatment. Participants also underwent abdominal magnetic resonance imaging (MRI) to assess rectus abdominis muscle thickness and subcutaneous adipose tissue thickness. Data was analyzed using IBM SPSS Statistics for Windows, version 28 (IBM Corp., Armonk, New York, United States). Results All participants completed the study with no loss to follow-up. Mean waist circumference decreased significantly by -2.76 ± 1.37 cm (<i>p</i> < 0.001), while mean body weight showed a non-significant reduction of -0.6 ± 1.35 kg (<i>p</i> > 0.05). MRI analysis demonstrated a significant increase in rectus abdominis thickness (+5.98 ± 1.87 mm, <i>p</i> < 0.001) and a significant decrease in subcutaneous adipose tissue thickness (-4.35 ± 2.80 mm, <i>p</i> < 0.001). All participants reported subjective improvement in abdominal strength and appearance. Conclusion FMS was associated with increased rectus abdominis muscle thickness, reduced abdominal subcutaneous adipose tissue, and decreased waist circumference in this pilot case series, with high patient satisfaction and no serious adverse events. These findings suggest that FMS may be a promising non-invasive option for abdominal shaping, but larger randomized controlled trials are necessary to confirm its efficacy and long-term benefits.