Independent and Combined Effects of Resistance Exercise Training and β-hydroxy β-methylbutyrate Plus Vitamin D

Independent and Combined Effects of Resistance Exercise Training and β-hydroxy β-methylbutyrate Plus Vitamin D on Body Composition and Skeletal Muscle Health

During middle-age, humans begin to lose muscle mass and strength. With increasing age the deterioration of muscle health is associated with a decline in quality of life and the loss of independence. β-hydroxy β-methylbutyrate (HMB) plus Vitamin D (VitD) have been proposed to increase skeletal muscle mass, contractile function and improve body composition but has yet to be evaluated in middle-aged women. The overall goal of this study is to determine the effects of HMB +VitD supplementation during 12 weeks of resistance exercise training or a non-exercise control on body composition, skeletal muscle size, and skeletal muscle function in middle-aged women.

To determine if HMB+VitD supplementation is an effective strategy to help prevent the loss of skeletal muscle size, skeletal muscle function and body composition in middle-aged women, forty eight women (45-60 yrs old) will be recruited to complete a 12-week intervention (n=12 per group; 4 groups). Participants will be randomized to complete a non-exercise control period or a resistance exercise training program. In a double-blinded fashion, participants in the non-exercise or resistance exercise groups will be randomized to consume either placebo or HMB+VitD. Before and after each intervention the investigators will evaluate skeletal muscle size, skeletal muscle function, and body composition.

Inclusion Criteria:

• Women between 45 and 60 years old
• Women with a BMI < 35 kg/m2
• Sedentary (< 30 minutes of structured physical activity 3 times per week)
• Weight stable for 3 months prior (+/- 5kg)

Exclusion Criteria:

• Body mass index > 35 kg/m2
• Type 1 or Type 2 diabetes
• Uncontrolled hypertension
• Active cancer, cancer in remission, or having received treatment for any form of cancer in the previous 5 years
• Cardiovascular disease (e.g., peripheral artery disease and peripheral vascular disease)
• Uncontrolled thyroid function
• Chronic and/or regular consumption of medication known to influence skeletal muscle metabolism
• Use of Vitamin D (>2000 IU) or β-hydroxy β-methylbutyrate
• Tobacco use
• Any condition that limits exercise training (e.g., chronic obstructive pulmonary disease, neuromuscular disorder, moderate or severe cognitive impairment, Alzheimer's disease, vertigo, dizziness)
• High alcohol consumption defined as more than 8 drinks per week for women
• Unwilling to undergo any study-related procedures
• Pregnancy
• Abnormal liver or kidney enzymes determined in blood chemistry panel
• Bleeding/clotting disorders or blood thinning medications (e.g., warfarin, heparin)