Sarcopenia is a pathophysiological process associated with aging and some metabolic conditions characterized by progressive muscle tissue loss, which may lead to loss of strength and performance and increased risk of falls and fractures, physical disability and premature death. With the present project the investigator aim to assess the effect of a feasible exercise program to improve muscle strength (primary outcome), and muscle volume and performance and other measures potentially associated with sarcopenia (secondary outcomes) in elderly and people living with HIV (PLWH) with sarcopenia. The investigators plan to enroll 98 elderly and 98 PLWH in a multicentric, 48-week, randomized, parallel-group, open label, superiority trial comparing the effect of a home-based and app-monitored strength exercise intervention versus no intervention. The investigators expect that participants who exercise will improve strength and other parameters and that improvement at week 12 and week 48 will be higher than in no-exercise controls.

Inclusion Criteria:

• Sedentary
• >60 year-old in the elderly group or >50 year-old for the PLWH group;
• with sarcopenia, as defined by both relative loss of muscle mass by bioimpedentiometry (BIA) and low muscle strength by handgrip

Exclusion Criteria:

• Any disease requiring hospitalization in the 6 weeks before enrollment;
• Medical conditions contraindicating the proposed exercise as established by a sport medicine specialist;
• Current substance or alcohol abuse or use of drugs that may influence balance and coordination;
• Not being able to walk without assistance and to perform the prescribed exercises as by protocol.