Effect NMES on physical performance in frail elderly during hospitalization

INTERVENTION: Neuromuscular electrostimulation of the m. quadriceps CONDITION: Fragility, Physical functioning, Frailty, Hospitalization, Sarcopenia, Neuromuscular electrostimulation ; ; PRIMARY OUTCOME: Short physical performance battery; ; HABAM; ; Knee extension; ; Muscle mass of the upper leg (m. quadriceps) determined by the use of the Maltron Bioscan 920‐II SECONDARY OUTCOME: Tolerance of NMES and side effects. ; ; Admission time in days ; ; Destination of dismissal; home or to a health facility ; ; Mortality INCLUSION CRITERIA: Frail elderly (defined by the GFI score, GFI > 3), 70 years and above, with a SPPB <6 on day <4 day after admission to the geriatric ward, duration of admission at least 7 days.