The Influence of Regular Beef Consumption and Protein Density of the Diet on Training-induced Gains in Muscle Strength and Performance in Healthy Adults

The Influence of Regular Beef Consumption and Protein Density of the Diet on Training-induced Gains in Muscle Strength and Performance in Healthy Adults

Humans lose muscle and strength as they get older. Further, ageing is accompanied by loss in cognitive function. It is not quite clear why this happens; however, it is known that the loss of muscle and strength can increase risk for physical and mental health risks and impair the ability of older people to remain physically independent. Weight lifting and proper nutrition, particularly eating high quality protein at the proper time and quantity, may help prevent these losses when a person gets older. To determine if regular beef consumption as part of a higher protein diet aids the muscle adaptive response to resistance training and improvements in cognition, seventy healthy individuals will be recruited to lift weights 3 times a week for 10 weeks. One group (n=36) will consume the Recommended Dietary Allowance (RDA) for protein (0.8g/kg/day), while the other group (n=36) will consume an amount twice the RDA (1.6g/kg/day), which is in agreement with recommendations from the American College of Sports Medicine. Participants will have their muscle strength tested and samples of blood and muscles will be collected before and after training to determine how the muscle adaptive response to resistance exercise is affected by higher protein intake. In addition, participants will undergo cognitive assessments at baseline and follow-up to determine the influence of improving muscle strength on attention and memory. Overall, the investigators proposed study will use sensitive methodology to determine if providing protein above the RDA and at optimal times during the day in combination with a weight lifting program can help make someone stronger and build larger muscles than someone consuming the RDA, as well as what processes may be responsible for helping the muscles to get bigger and stronger.

Inclusion Criteria:

• Non-obese adults: BMI <30 kg/m2
• Aged between 40-64 years
• Sedentary
• Weight-stable for 6 months prior

Exclusion Criteria:

• Allergies to beef consumption
• Phenylketonuria (PKU)
• BMI >30 kg/m2
• history of active cardiovascular disease, diabetes mellitus, GI disorders, musculoskeletal/orthopedic disorders (e.g. osteoarthritis, rheumatoid arthritis, tendinitis, gout, fibromyalgia, patellar tendinopathy, or chronic low back pain)
• hypersensitivity or allergy to antibiotics
• Kidney, urinary, or liver conditions
• Epilepsy
• Diagnosed mental illness
• have bleeding or clotting disorders (or take related medications e.g.. Coumadin/ low dose Aspirin)
• High alcohol consumption
• use tobacco
• uncontrolled hypertension
• vegan/vegetarian diets
• on medications known to affect protein metabolism (i.e. corticosteroids, androgen/estrogen containing compounds, non-steroidal anti-inflammatories)
• habitual consumption of high (>1.8 g protein/kg/d) or low (<0.66 g protein/kg/day)
• pregnancy
• supplements that influence protein metabolism (e.g. omega 3 fish oils)