
2.1. Participants
myopathy, low back pain, epilepsy
MYOPATHY, EPILEPSY
The sample size was calculated using the Gpower 3.1 program. For an effect size of 0.25, error probability of 0.05, and power of 0.90, 38 participants were defined. Considering the 10% dropout rate, we recruited 41 healthy subjects (male = 17, female = 24). The inclusion criteria were as follows: age between 20 and 25 years, not engaged in elite sports, lack of any history of spinal surgery or persistent low back pain, lack of any medical conditions that affect muscle metabolism, such as myopathy, and lack of any medical history that might be affected by EMS, such as epilepsy or cardiac pacemaker insertion. All participants provided written informed consent prior to participation. The study was approved by the Institutional Review Board of Korea University Anam Hospital (2021AN0557). A CONSORT diagram is shown in Figure Flowchart of the study.