Research indicates that lower extremity muscle weakness in the elderly is consistently related to impaired mobility and fall risk. Reversible components of the muscle weakness of aging include underuse syndromes and undernutrition, both of which are prevalent in nursing home populations. The Boston FICSIT study is a nursing home-based intervention to improve muscle strength through progressive resistance training of the lower extremities and/or multi-nutrient supplementation in chronically institutionalized subjects aged 70-100. Baseline measurements of falls, medical status, psychological variables, functional status, nutritional intake and status, body composition, muscle mass and morphology, muscle function, and gait and balance are taken. The nursing home residents are then randomly assigned to one of four treatment groups for 10 weeks: (1) high intensity progressive resistance training of the hip and knee extensors 3 days per week; (2) multi-nutrient supplementation with a 360-kcal high carbohydrate, low fat liquid supplement every day; (3) a combination of groups (1) and (2); and (4) a control group. Both non-supplemented groups receive a liquid placebo every day, and both non-exercising groups attend three sessions of "leisure activities" every week in order to control for the attentional aspects of the exercise and nutritional interventions. At the end of the 10-week period, all baseline measurements are re-assessed.