Abstract
BackgroundAge-related muscle wasting has been strongly implicated with falls and fractures in the elderly, but it has also been associated with cognitive decline and dementia. Progressive resistance training (PRT) and adequate dietary protein are recognised as important contributors to the maintenance of muscle health and function in older adults. However, both factors also have the potential to improve brain function and prevent cognitive decline via several pathways, including the regulation of various growth and neurotrophic factors [insulin-like growth factor-1 (IGF-1)]; brain-derived growth factor (BDNF)] and/or the modulation of systemic inflammation. The primary aim of this study is to investigate whether a modest increase in dietary protein achieved through the consumption of lean red meat three days per week, when combined with PRT, can enhance muscle mass, size and strength and cognitive function in community-dwelling older people.Methods/DesignThe study design is a 48-week randomised controlled trial consisting of a 24-week intervention with a 24-week follow-up. Men and women (n=152) aged 65 years and over residing in the community will be randomly allocated to: 1) PRT and provided with 220 g (raw weight) of lean red meat to be cooked and divided into two 80 g servings on each of the three days that they complete their exercise session, or 2) control PRT in which participants will be provided with and advised to consume ≥1 serving (~1/2 cup) of rice and/or pasta or 1 medium potato on each of the three training days. The primary outcome measures will be muscle mass, size and strength and cognitive function. Secondary outcomes will include changes in: muscle function, neural health (corticospinal excitability and inhibition and voluntary activation), serum IGF-1 and BDNF, adipokines and inflammatory markers, fat mass and inter-/intra-muscular fat, blood pressure, lipids and health-related quality of life. All outcome measures will be assessed at baseline and 24 weeks, with the exception of cognitive function and the various neurobiological and inflammatory markers which will also be assessed at week 12.DiscussionThe findings from this study will provide important new information on whether a modest increase in dietary protein achieved through the ingestion of lean red meat can enhance the effects of PRT on muscle mass, size and strength as well as cognitive function in community-dwelling older adults. If successful, the findings will form the basis for more precise exercise and nutrition guidelines for the management and prevention of age-related changes in muscle and neural health and cognitive function in the elderly.Trial registrationAustralian New Zealand Clinical Trials Registry: ACTRN12613001153707. Date registered 16th October, 2013.
Highlights
Age-related muscle wasting has been strongly implicated with falls and fractures in the elderly, but it has been associated with cognitive decline and dementia
The findings from this study will provide important new information on whether a modest increase in dietary protein achieved through the ingestion of lean red meat can enhance the effects of Progressive resistance training (PRT) on muscle mass, size and strength as well as cognitive function in community-dwelling older adults
In a recent 4-month randomised controlled trial (RCT) in women aged 60 years and over, we found that ingestion of two ~80 g servings of cooked lean red meat on most days of the week enhanced the effects of PRT on muscle mass, strength and serum insulin-like growth factor-1 (IGF-1) and reduced inflammation [serum IL-6]; there were no adverse effects on blood pressure, lipids or kidney function [15]
Summary
Age-related muscle wasting has been strongly implicated with falls and fractures in the elderly, but it has been associated with cognitive decline and dementia. In a recent 4-month randomised controlled trial (RCT) in women aged 60 years and over, we found that ingestion of two ~80 g servings of cooked lean red meat on most days of the week enhanced the effects of PRT on muscle mass, strength and serum insulin-like growth factor-1 (IGF-1) and reduced inflammation [serum IL-6]; there were no adverse effects on blood pressure, lipids or kidney function [15]. Despite these positive findings, promoting daily consumption of red meat is not consistent with the current Australian Dietary Guidelines [21]. Further research is needed to determine whether less frequent consumption (e.g., an intake consistent with current dietary guidelines of no more than 455 g per week of cooked lean red meat) is effective when consumed in combination with exercise
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