Nutritional Intervention for Age-related Muscular Function and Strength Losses

The purpose of the study is to * Test the effect of a dietary supplement beta-hydroxy-beta-methylbutyrate (HMB) with and without Vitamin D to prevent and reverse the losses of muscular strength and functionality in older adults. The second aim of the study is to determine if HMB and Vitamin D improves markers of bone turnover in adults aged 60 plus years. HMB is a dietary supplement that comes from the amino acid leucine. HMB is found in foods and is made in your body after you eat protein (meat). Subjects will be randomized to one of four dietary supplement groups and will participate in a 3-day per week exercise program for 12 weeks. Each exercise day will be about 60 minutes long consisting of strength training exercises utilizing Theraband® stretch cords and jumping. Subjects will consume the dietary supplement 2 times per day for 12 weeks. Tests will consist of the following: * Measuring the strength of subjects' legs by using a Isokinetic Dynamometer * Measuring body composition * Measuring hand-grip strength using a hand-grip dynamometer * Measuring functional mobility, balance and agility by the time it takes for you to rise from a chair, walk around a cone 8 feet in front of the chair and return to the chair (Up-\&-Go Test * Filling out questionnaires and having blood drawn for biochemical measurements. Testing will be performed at the beginning and at 4, 8 and 12 weeks.