The Impact of Plant-based Blends on Skeletal Muscle Protein Synthesis Rates in Older Adults

The Impact of Plant-based Protein Blends, With or Without Resistance Exercise, on Skeletal Muscle Protein Synthesis Rates in Older Men and Women

Lifestyle interventions such as physical activity and dietary habits are the most effective non-pharmacological strategies to combat the loss of muscle mass and the development of mobility limitations with aging. Resistance training (i.e., strengthening exercise) provides a strong stimulus to build muscle mass, and protein provides the essential building blocks. Therefore, an individual's dietary practices can influence the effectiveness of an exercise program - when combined, they work together to increase the muscle-building response. However, not all proteins are equally effective at bringing about muscle growth.

Therefore, the purpose of this study is to investigate the effect of a higher-quality plant-based protein blend with lifting weight on muscle building in older men and women.

Dietary interventions are similarly pertinent in preventing skeletal muscle mass losses with aging. Dietary protein ingestion provides the necessary substrates (i.e., amino acids) essential for skeletal muscle development, health, and, thus, maintenance of muscle mass. Protein ingestion and resistance exercise training (RET) increase muscle protein synthesis (MPS), but when combined, they act synergistically to maximize MPS. Importantly, not all protein sources are equivalent in their ability to support increased rates of MPS. A recent study confirmed that a blend of plant proteins at a large dose of 30 g resulted in similar MPS as 30g of milk protein in young men. However, the impact of a unique plant-derived protein blend on MPS in older individuals is yet to be determined. Therefore, the purpose of this study is to address that knowledge gap by assessing the skeletal muscle anabolic potential of a plant-based protein blend (i.e., corn and pea) on rates of MPS, with or without additive exercise in older men and women.

Inclusion Criteria:

• Older (60-80 y) men and women
• Be in good general health
• Non-smoking
• Recreationally active but not meet Canada's Physical Activity Guidelines (150 min of moderate-intensity exercise/week)
• Have a body mass index (BMI) between 18.5-30 kg/m2 (inclusive)
• Willing and able to provide informed consent (speaks and understands English)

Exclusion Criteria:

• Use of tobacco or related products
• Use assistive walking devices (e.g., cane or walker)
• Any concurrent medical, orthopedic, or psychiatric condition that, in the opinion of the investigator, would compromise his/her ability to comply with the study requirements
• History of cancer within the last 5 years, except basal cell carcinoma, non-squamous skin carcinoma, prostate cancer or carcinoma in situ with no significant progression over the past 2 years
• Significant orthopedic, cardiovascular, pulmonary, renal, liver, infectious disease, immune disorder, metabolic/endocrine, neuromuscular or bone wasting disorders
• Any cachexia-related condition (e.g., relating to cancer, tuberculosis or human immunodeficiency virus infection and acquired immune deficiency syndrome) or any genetic muscle diseases or disorders
• History of statin myalgia
• Current illnesses which could interfere with the study (e.g., prolonged severe diarrhea, regurgitation, difficulty swallowing)
• Excessive alcohol consumption (>21 units/week)
• History of bleeding diathesis, platelet or coagulation disorders, or antiplatelet/anticoagulation therapy (up to 81mg of baby aspirin per day taken as a prophylactic is permitted).
• Routine/daily usage of non-steroidal anti-inflammatory drugs (NSAIDS, prescription use or daily use of over-the-counter medication), use of corticosteroids, testosterone replacement therapy (ingestion, injection, or transdermal), any anabolic steroid, creatine, whey protein supplements, casein or branched-chain amino acids (BCAAs) within 45 days prior to screening.
• A history of falls determined by a score >25 on the Falls Efficacy Scale-International (FES-I).