NCT02347137

Influence of Reduced Daily Step Count and Anabolic Interventions on Muscle Protein Metabolism in Older Persons

Efficacy of Isolated Whey and Micellar Whey Protein (+/-Citrulline) to Stimulate Protein Synthesis in 'Healthy' and 'Anabolically Resistant' Elderly Muscle

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 30 (actual)
• Sponsor: McMaster University · Academic / Other
• Sex: Male
• Age: 65 Years – 80 Years
• Healthy volunteers: Accepted

Summary

As the loss of muscle mass with aging is associated with a dysregulation of muscle protein synthesis (MPS) that is generally characterized by an 'anabolic resistance' to nutrients, the primary outcome of the trial is to investigate the effect of a mixed macronutrient beverage on post-prandial myofibrillar MPS. However, the 'anabolic resistance' of aging may be predominantly influenced by the contractile activity of skeletal muscle; for example, the investigators have demonstrated that 2 weeks of reduced habitual activity (i.e. daily step count) induces anabolic resistance in otherwise healthy older adults. In contrast, resistance exercise is well-known to enhance muscle mass and can increase the sensitivity of skeletal muscle to dietary amino acids. Therefore, all participants will undergo a 2-week reduced step count intervention combined with a unilateral leg resistance exercise protocol to induce an 'unhealthy' or 'anabolically resistant' leg and a relatively 'healthy' or 'anabolically sensitive' leg, respectively; this within subject model will be utilized to investigate the effect of the mixed macronutrient beverage in both relatively 'healthy' and 'unhealthy' older muscle. The investigators will also measure changes in muscle mass, muscle function, and cardiovascular health of both legs before and after the 2-week intervention to determine the effect of reduced activity and the protective effect of minimal, low-intensity exercise on these outcomes.

Conditions

• Older Adults
• Muscle Protein Synthetic Response to Protein
• Reduced Physical Activity

Interventions

Type	Name	Description
OTHER	step-reduction	reduce daily physical activity to less than 1500 steps per day
OTHER	step-reduction plus resistance exercise	reduce physical activity to less than 1500 steps per day with thrice weekly low-load, high effort resistance exercise

Timeline

• Start date: 2012-07-01
• Primary completion: 2013-05-01
• Completion: 2013-05-01
• First posted: 2015-01-27
• Last updated: 2015-01-27

Locations

1 site across 1 country: Canada