 Our goal is to establish if specific interventions that can acutely increase muscle protein synthesis can also effectively translate into increased muscle mass andor performance in older sedentary people, thus preventing frailty and promoting physical independence. To this end we will use stable isotope methodologies to measure muscle protein metabolism and contrast enhanced ultrasound to measure muscle perfusion, in order to determine if the treatments acute effects can predict their chronic impact on muscle mass and function. We will also determine if chronic treatment leads to metabolic andor vascular adaptations that may explain the measured changes in muscle mass and function. 