03/06/2021 by Harriet Morphy-Morris 0 Comments
Ageing, Exercise and Nutrition: Increased Levels of Exercise combined with Protein Consumption Reduces the Impact of Sarcopenia.
Research carried out by the University of Birmingham supports the correlation between exercise, dietary protein quality, and the maintenance of healthy muscle function with ageing.
With ageing, a loss of muscle mass and strength is observed (defined as ‘Sarcopenia’), increasing the risk of falls, fractures and early mortality. Sarcopenia is also associated with acute and chronic disease states and increased insulin resistance (i.e., risk of developing diabetes).
This age-related decline in muscle mass and strength occurs at an annual rate of ~1% and 3%, respectively, from approximately the fifth decade of life. Alarmingly, sarcopenia presents a significant health and economic burden in the UK, highlighting the importance of research investigating its underpinning mechanisms and management/therapeutic treatment.
Sarcopenia is estimated to impact around 30 million older individuals across Europe, at an annual cost to the UK health services of £2 billion. Therefore, developing strategies to counteract this age-related loss of muscle mass and function are essential to extend the number of years an individual spends in good health and to reduce the burden on the NHS and the UK economy.
We interviewed one of our clients, Dr Paul Morgan, a Research Fellow who works within the Metabolic and Molecular Physiology research group, led by Dr Leigh Breen, from the University of Birmingham, to discuss the insights of their ongoing research:
- How will the focus of this research impact the older generation of society?
The ultimate focus of our research is to improve our understanding of the factors that regulate skeletal muscle changes in older age and to identify how to use nutrition and exercise, mainly protein nutrition, to extend the healthspan by attenuating the loss of muscle and function in ageing, thus maximising independence and quality of life in older age.
The main issue with losing muscle mass, as you might suspect with ageing, is the loss of function. This loss of function ultimately places the majority of individuals beyond the ‘disability threshold’ as they age, reducing the ability to perform activities of daily living (i.e., walking, cleaning, cooking, shopping) and placing them dependent on a number of services. Alarmingly, the consequences of muscle loss are multi-faceted and associated with a number of other comorbidities. For example, muscle is the largest organ for glucose (sugar) disposal and, as such, muscle loss places a further strain on an individual’s metabolic health as a result of a reduced ability to store glucose.
- Are there any controversies in lifestyle that you hope to address within the research?
Quite often society is too cautious with our older populations especially when it comes to exercise. But ironically this perception feeds into the disease (i.e., sarcopenia and other age-related comorbidities).
We, and others in the field, have found that to get the same response from the muscle as a younger healthy adult, older individuals need to perform higher intensity exercise and/or increase the volume of exercise, as the muscle becomes less responsive to adaptation following an anabolic stimulus (i.e., protein and exercise) with ageing. This goes against what most people would automatically assume and perhaps what is typically ‘accepted’ in society. We find that if you only do a small amount of exercise as an older individual, or if it is performed at too low of intensity, you simply don’t get a robust response from the muscle and/or comparable response relative to younger individuals, to promote adaptation.
From the studies we, and others, have conducted, we have found that older adults are so much more physically capable than what society perceives and perhaps that proportion of society needs better recommendations and communications to ensure the right types of exercise are performed alongside appropriate nutrition (the importance of public engagement!). It’s never too late to start exercising either. We have shown that despite better preservation of muscle function and metabolic health in lifelong exercisers (termed ‘masters athletes’), comparable muscle-building responses are observed between lifelong endurance-trained older athletes compared with untrained older individuals.
However, it is pertinent to note that expert advice must be sought from an appropriately qualified individual prior to starting a high-intensity exercise regime, to ensure it is safe to do so. Further, as with all diet and exercise programming, we encourage gradual progress/changes to an individual’s lifestyle.
- Is there a specific age where you should start eating a larger amount of protein?
Not necessarily. However, research suggests that older adults need to consume more protein per meal to maximise the response within the muscle, in order to help build muscle and support maintenance of muscle in older age.
Recent advances in the guidelines on daily dietary protein intakes in older adults have moved towards recommendations on a meal-by-meal, rather than on a total daily, basis. This is largely because the fate of ‘excess’ ingested protein contained within one meal is primarily oxidation and/or excretion, rather than supporting muscle building, as there seems to be a ceiling for the amount of protein that can be absorbed at one given time. Further, excess protein cannot be stored within the body.
‘Anabolic resistance’ is a term that refers to reduced stimulation of muscle-building processes to a given dose of anabolic stimulus (i.e., protein, exercise) and contributes to the age-related decline in skeletal muscle mass.
Indeed, as discussed above with exercise, whilst young individuals demonstrate a pronounced response to these anabolic stimuli, a blunted response is typically observed in older adults. The maximal stimulation of muscle-building processes occurs at much lower relative dosages in younger adults (~0.24 g per kg of body mass), compared with older adults (~0.40 g per kg of body mass). This equates to an approximate per meal dose of>30 g for a typical older individual, as opposed to <20g for a typical younger adult. Assuming ~3-4 meals per day (~3 hours between meals), this equates to ~1.6 g of protein per kg of body mass per day. In practice, ~100 g of lean beef, ~550 mL of semi-skimmed milk or 3-4 whole eggs are examples of foods containing ~20 g of protein. However, older adults also typically consume protein in a skewed distribution, and this may influence the capacity to optimize muscle building processes and thus the rate of sarcopenic progression (i.e., muscle loss with ageing).
Whilst the considerations of the intricacies of protein intake go beyond the scope of this article, interestingly, as well as the quantity consumed, the source and quality of protein are also important factors. Higher quality proteins (i.e., those that provide a full complement of sufficient amino acids) include, for example, eggs and dairy proteins such as milk, whey, casein and egg. We have recently shown that protein ‘quality’ significantly influences the muscle-building response as well as chronic changes in strength (when combined with an exercise programme) in young and old adults. We also found that the quality of protein might be particularly important in older adults and/or when protein intake is at the lower end of what is required to support muscle building, which may have important implications for protein recommendations.
Nevertheless, a combination of lower-quality (i.e., plant-based) proteins can be consumed in combination as a blend to achieve a comparable response to higher quality proteins. Future guidelines on protein recommendations for older individuals should continue to be refined to consider a number of these factors as well as the influence of exercise and sleep. However, it is important to note that exercise remains the most potent stimulus for muscle adaptation and the attenuation of age-related muscle loss.
- Tell us about the perceptions society has about the amount of protein you should consume?
Protein remains a controversial topic. There is a fault process, and a misconception that a higher dose of protein over time will lead to damage of the kidneys but yet no evidence exists to support this hypothesis. The only current plausible link between protein intake and kidney damage is in people with already existing poor kidney function. Indeed, it was originally proposed that habitual consumption of excessive dietary protein negatively impacts kidney function by a sustained increase in glomerular pressure and renal hyperfiltration (i.e., excretion by the kidney of excess protein). However, in humans, there is no evidence that this occurs. Interestingly, recent studies suggest that higher relative protein intake in subjects with normal kidney function seems to be associated with a lower risk of end-stage kidney and chronic kidney disease. It has also been suggested that high protein intake may lead to an acidic environment and cause leaking of calcium from the bones (termed the ‘acid-ash hypothesis’). In direct contrast, protein consumption is actually associated with bone-supporting mechanisms and adaptation in healthy individuals, assuming sufficient provision of calcium and vitamin D within the diet. Indeed, bone is ~40% protein.
One topic that we have found challenging at public engagement events is discussion around the use of protein supplements in older adults which can often seem controversial in society, perhaps due to the typical population that advertising is directed towards and/or misleading perceptions of such products. I wouldn’t recommend protein supplements as a replacement for whole foods but I would recommend them as a supplement (when sourced from a reputable supplier with sufficient testing) to, as their name suggests, enhance (or ‘top up’) an individual’s dietary protein intake, as required. This is particularly important in older individuals who are known to have a suppressed appetite and find it difficult to consume sufficient amounts of protein.
Choice TeleMed supported this research with our team of advisors in radiation compliance and obtaining research ethics committee approval.
You can also follow Dr Morgan and Dr Breen’s research via Twitter @_PaulMorgan and @LeighBreen where they regularly promote and/or discuss pertinent research to the field(s) of skeletal muscle ageing and protein metabolism.