The purpose of this study is to determine whether a nutritional supplement with an amino acid called leucine along with resistance exercise are effective in the improvement of muscle strength and quality of life in elderly people.

Physiological aging is accompanied by functional loss and changes in different organs, including the skeletal muscle, with a progressive reduction in muscle mass. This is called physiological sarcopenia of the elderly.

In any population of autonomous individuals over 65 years, a proportion between 3% and 32% depending on age, meets the criteria of the so-called Frailty Syndrome. Frailty is characterized by a decrease in reserves and resistance to aggression, conferring increased vulnerability, disability and poor vital prognosis.

A feature of the Frailty Syndrome is the potential reversibility of many of the elements at the initial stages of frailty. Currently, available treatment for frailty is limited. One of the tools should be the prevention of sarcopenia, where nutritional treatment and exercise have a vital role.

Protein synthesis in aged muscle can be improved by increasing leucine concentration above physiological levels by a higher intake. Regarding exercise, progressive resistance training is one of the interventions that have shown better results in the increase of mass and muscle strength in elderly people.

The hypothesis raises the possibility that an intervention consisting of a leucine supplement along with progressive resistance training, is superior to the same training program and a placebo in improving muscle strength and quality of life in elderly people.

Inclusion Criteria:

• Over 70 years of age.
• Subjects capable of doing resistance exercise.

Exclusion Criteria:

• Hospitalized patients.
• Disabled patients (i.e., not being able to exercise).
• Patients that usually train in resistance exercise.
• Patients with chronic renal failure.
• Patients with a fractured extremity during the last 6 months.
• Patients that follow diets with a protein restriction.
• Patients with oral nutritional support, enteral or parenteral nutrition.
• Patients in a low calorie diet to lose weight.
• Patients using pharmacological treatment with anorexigenic effects, anabolic steroids or corticosteroids.
• Patients with cognitive impairment or major psychiatric disorder.
• Non-signed informed consent.
• Any patient not capable to properly follow the treatment or not considered adequate by the researchers.