Inclusion Criteria:  aged 65 years and older frail according to Tilburg Frailty Indicator residing in assisted living facility or nursing home able to walk 4m w/o walking aid but without personal assistance no prior WB-EMS exposure  Exclusion Criteria:  severe visual or hearing impairments major cognitive impairment (MMSE <10) medications with muscle-anabolic effects medical conditions affecting trainability of muscles (e.g. Myasthenia gravis, Cushing syndrome, Morbus McArdle) surgery within past two months history of rhabdomyolysis medical conditions affecting sensation of electrical stimuli (e.g. severe polyneuropathy) severe renal insufficiency (eGFR<30 ml/min/1.73m²) electronic implants acute or untreated abdominal wall or inguinal hernia Ventricular arrhythmias requiring therapy