Muscle and strength adaptations to pulsed electromagnetic field in young women: a pilot intra-individual study

Introduction: Pulsed elec-tromagnetic field (PEMF) has been proposed as a non-invasive tool to promote muscle adaptations such as strength gains (1RM) and increased muscle thickness (MT). How ever, the effects of PEMF on lower-limb muscles in young untrained individuals remain underexplored. Methods: We investigate the effects of an eight-week PEMF intervention on rectus femoris (RF) MT and 1RM in 5 sedentary women. Each participant had one leg randomized to PEMF and the contralateral leg to traditional resistance training on a leg extension machine (EXT). The PEMF protocol consisted of 30-minute (3x/week), at a frequency of 50Hz-3.5 Teslas. The EXT protocol involved 3sets of 8–12reps at ~70%1RM. MT was measured at RF 30% and 50% of thigh length via ultrasound, and 1RM was assessed bilaterally. Perceived exertion (RPE) was recorded after each session.Results: PEMF: mean RFMT increased from 1.88±0.23cm to 1.92±0.19cm at 30% thigh length and from 1.79±0.19cm to 1.84±0.13cm at 50% thigh length. EXT: RFMT in-creased from 1.88±0.14cm to 2.01±0.18cm at 30% and from 1.70±0.33cm to 1.88±0.27cm at 50%. 1RM improved from 36.0±4.7kg to 40.4±5.7kg for PEMF and from 36.0±7.5 kg to 46.6±9.1kg for EXT. Mean session RPE was 3.0±0.9 for PEMF and 8.0±1.0 for EXT. Discussion: These preliminary findings highlight the potential of PEMF as a low-exertion alternative and provide key parameters for designing a future definitive trial. Conclusion: Both interventions led to improvements in 1RM, while changes in MT were modest and more variable. The PEMF sessions were consistently well tolerated and RPE as requiring low effort.