Pulsed electromagnetic field (PEMF) promotes muscle hypertrophy, increased maximum strength and strength endurance in untrained adults: a randomised parallel design

Purpose Investigate the effects of 8 weeks of PEMF on musclethickness (MT) of the proximal (RF30%) and mid (RF50%) rectus femoris, and mid vastus lateralis (VL50%), as well as on maximal strength (1RM) and strength endurance (60%1RM) in untrained, compared to resistance training (RT). Methods This is a chronic, randomised, and parallel experimental trial. Eighteen untrained individuals (13 women) were randomly assigned to PEMF (n = 10; 22.9 ± 2.4 years) or bilateral leg extension (EXT, n = 8; 23.2 ± 3.9 years), 3×/week (8 weeks) training. PEMF involved 30-min sessions with magnetic flux densities ranging from 2.8 to 7.0 teslas, with applicators placed over the RF and VL. The EXT group completed 3 sets of bilateral knee extensions at 8–12RM with one-minute rest. Assessments included 1RM and 60%1RM unilateral knee extensions and MT via ultrasound on the legs. Results RF30% MT increased post-intervention (p = 0.006), with no group differences (p = 0.570). No changes were found in the left RF30% or RF50% of either leg. An increase in VL50% MT was observed in the left leg (p = 0.032). Wilcoxon revealed 1RM gains in both legs for PEMF (right: p = 0.012; left: p = 0.035) and EXT (right: p = 0.034; left: p = 0.018). There were no differences between groups in 1RM. Both groups also showed improvements in 60%1RM (p = 0.011; p = 0.018), with no between-group differences (p = 0.392; p = 0.858). Conclusions The present study offers preliminary evidence that continuous PEMF application, even in the absence of mechanical overload, can elicit improvements in muscle morphology, maximal strength, and muscular endurance in untrained individuals.