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.

Subjects must meet all of the inclusion criteria in order to participate in the study.

• Male and Female subjects will be enrolled into the study.
• Age > 60 years.
• Free of liver and kidney diseases, and with no evidence of uncontrolled hypertension.
• Does not have a chronic disease that affects calcium or bone metabolism (i.e., asthma with chronic use of high dose steroids, inflammatory bowel disease, Crohn's disease, primary hyperparathyroidism, seizure disorder with use of phenobarbital, etc.).
• Not classified as morbidly obese (body mass index (BMI) >40 kg/m2).
• Six weeks since major surgery (three weeks since minor surgery).
• Willing to consume one of the nutritional supplements for the study period.
• Individuals diagnosed with osteoporosis (i.e., bone density > 2.5 standard deviations below the mean) will not be enrolled in the study.
• No other serious medical illness.
• Serum 25OH-VitD3 >10 and <25 ng/ml.
• Able and willing to participate in 3-day-a-week monitored strength-training program.
• Physician has placed no restriction on physical exercise.

All candidates meeting any one of the exclusion criteria will not be enrolled into the study and as necessary will be referred to their private physician for further follow-up.

• Age < 60 years.
• Evidence of liver and kidney diseases, uncontrolled hypertension, or Type I diabetes mellitus requiring insulin for glucose control.
• Presence of a chronic disease that affects calcium or bone metabolism (i.e., asthma with chronic use of high dose steroids, inflammatory bowel disease, Crohn's disease, primary hyperparathyroidism, seizure disorder with use of phenobarbital, etc.).
• Classified as morbidly obese (body mass index (BMI) >40 kg/m2).
• Less than six weeks since major surgery or three weeks since minor surgery.
• Not willing to consume one of the nutritional supplements for the study period.
• Individuals diagnosed with osteoporosis (i.e., bone density > 2.5 standard deviations below the mean) will not be enrolled in the study.
• Other serious medical illness, which the subjects doctor or medical review team has decided affects the subject's ability to participate in the study.
• Subjects on high dose vitamin D therapies (i.e. 50,000 IU vitamin D).
• Subjects with serum 25OH-VitD3 <10 ng/ml will be considered deficient and will be referred to their physician for treatment.
• Subjects with serum 25OH-VitD3 >25 ng/ml.
• Not able or willing to participate in 3-day-a-week monitored strength-training program.
• Physician has placed a restriction on physical exercise.