Strength in ageing: the role of protein and resistance training

We’re all getting older and living longer lives than ever before. But as we age, we are faced with a higher risk of nutritional frailty. This is marked by unintentional weight loss, loss of muscle mass and strength which increases the likelihood of disability. In this podcast episode, I highlight how our nutrition needs change as we age and why a firm focus is needed in preserving muscle mass through a combination of resistance exercise and additional protein.

Links referred to in the podcast

• Review of protein supplementation combined with resistance training in older adults https://pubmed.ncbi.nlm.nih.gov/38753309

Episode transcript
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Transcript

We’re all getting older and living longer lives than ever before. But as we age, we are faced with a higher risk of nutritional frailty. This is marked by unintentional weight loss, loss of muscle mass and muscle strength which increases the likelihood of disability. In this podcast episode, I highlight how our nutrition needs change as we age and why a firm focus is needed in preserving muscle mass through a combination of resistance exercise and additional protein.

The world’s population is ageing. We’re living longer and with that comes many potential health problems. One of those is nutritional frailty which is a state commonly seen in older adults. It is characterised by significant loss of weight, muscle mass and strength – making the person susceptible to disability. This is all impacted by chronic undernutrition, the presence of disease, hormonal changes and decreased physical activity. Which then leads to sarcopenia.

Sarcopenia is marked by the gradual loss of muscle mass and strength with age. It is linked to physical disability, poor quality of life and earlier death. Ageing is a primary cause of sarcopenia. The decline in physical activity, motor neuron recruitment and anabolic hormones, along with chronic inflammation seen in age can make sarcopenia worse.

Managing sarcopenia relies on resistance exercise and getting plenty of protein in the diet. For older adults with sarcopenia, protein intakes of up to 1.5 grams per kilogram of body weight is recommended. Combined with resistance exercise, this helps maintain and rebuild muscle mass.

This is why interventions designed to maintain or improve muscle in older adults are critical for promoting healthy ageing. Resistance training alone has long been recognised as an effective strategy to combat age-related declines in muscle mass and strength. So how much greater benefit could it have if extra protein is taken along with it? That was a question asked in newly published research where the research team wanted to see how resistance training combined with supplemental protein could affect gait speed.

Gait speed (which in everyday language simply means walking speed) is a very relevant and functional measure of muscle strength and mobility because it looks at how well a person can move through their normal daily activities. A slow walking speed is linked to a higher risk of falls, disability, cognitive problems and earlier death.

It is not the fact a person is moving slowly that directly affects those outcomes; it is more that a slower gait speed is a functional signal that a person may be in decline health wise and muscle mass and strength are important parts of that.

There is no one single ‘best’ gait speed, but pooled research has found that gait speeds faster than 1.0 m/s suggest healthier ageing, while speeds slower than 0.6 m/s indicate an increased risk of adverse health outcomes. Simply put: the longer it takes you to walk from A to B, especially if that has been getting slower over time, the more it says about your mobility, strength and balance.

In this new systematic review of the research it could include 18 randomised controlled trials involving over 1,100 older participants aged between 62 and 87 where protein supplementation or a placebo control was used to explore its effect on gait speed. And it wasn’t just healthy people in the study, but also included people who were considered frail, had sarcopenia or who were obese.

The types of additional protein used included milk, whey protein, casein protein, soy protein and mixtures of different protein sources with doses ranging from 10 to 45 grams per day. The placebo groups received a carbohydrate-based drink but with no additional protein.

The type of resistance training performed varied across studies, but the common theme was exercises that targeted the major muscle groups such as squats, leg press and bench press with typical volumes of several sets of 8 to 12 repetitions for each exercise spread across several sessions in a week. And I’ll link to the paper in the show notes. https://pubmed.ncbi.nlm.nih.gov/38753309

So, what did they find? The results were positive with supplemental protein combined with resistance exercise leading to improved walking speed compared to resistance training alone. And that benefit was magnified in studies that ran for longer than 12 weeks. And interestingly, for studies where the supplemental protein was taken after exercise, they could show a greater benefit on walking speed.

The findings from this research certainly don’t stand alone as there is already plenty of research to show the benefits of protein combined with resistance training in younger and more healthy populations and is why recommendations for this sort of active sportsperson group can sit in the range of 1.2 grams to 1.7 grams of protein per kilogram of body weight.

So back to the point that there may be a greater benefit in older adults for taking on additional protein after exercise. It firstly doesn’t mean that the body isn’t responsive to protein nutrients over a longer period. And at least in younger healthier groups, the timing of protein probably isn’t that important – the mythical ‘post exercise anabolic window’ is open for many hours. What is by far more important is meeting total protein needs over the course of the day. But with age, the situation can change a little and it may be harder to meet those protein goals so having a strategy of taking on extra protein after resistance exercise as part of their routine can help older adults meet their protein needs consistently.

The other important take-away from the analysis is that intervention periods exceeding 12 weeks gave greater improvements in walking speed. This isn’t so surprising, but also shows that a focus on protein and resistance exercise is a long-term game – move it, use it or lose it to get and maintain meaningful improvements in physical function.

But no study is perfect even with the promising results found. For a start there were a range of protein types, dosages and training protocols used which resulted in a lot of variability. Though this also reflects the real world in the differences in how people eat and exercise so the need for prescriptive advice may not be as important above getting plenty of protein and engaging in resistance exercise several times a week.

So, let’s wrap all this up. Some aspects of ageing may be inevitable, but the risk of specific age-related diseases and disability may, in part, be modified by dietary and lifestyle choices. This means that nutrition becomes even more important in older age when you consider how many barriers can arise to eating well. Two of the most important aspects of ageing well come from regular resistance exercise and meeting a higher goal for protein which together can help fight against age-related loss of muscle mass and lowering risk of older age disability.

So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.

If you find this podcast of value, then please consider sharing it with your friends and colleagues. This all helps to increase the reach of the podcast, which means a big win for credible evidence-based nutrition messages and making the world a slightly less confusing place.

I’m Tim Crowe and you’ve been listening to Thinking Nutrition.