Feel like your muscles are finding it harder and harder to cope as you get older? Well, a new ‘atlas of ageing’ could explain why – and may even lead to treatments to prevent it.
Published in Nature Ageing, the atlas reveals the complex changes caused by ageing to muscles at the cellular and molecular level. It also shows that our muscles fight ageing – a discovery that could help scientists develop new treatments to improve our bodies as we age.
As we age our muscles weaken, which can make everyday activities like standing and walking difficult – yet we still know very little about why this happens. Frailty can also lead to increased falls, immobility and loss of autonomy.
“With these new insights into healthy skeletal muscle ageing, researchers all over the world can now explore ways to combat inflammation, boost muscle regeneration, preserve nerve connectivity, and more,” said senior author Dr Sarah Teichmann from the Wellcome Sanger Institute.
“Discoveries from research like this have huge potential for developing therapeutic strategies that promote healthier ageing for future generations.”
As longevity expert Andrew Steele explains: "Every year after the age of 30, we lose 1 per cent of our strength, and understanding why is critical to helping us all stay strong and independent into older age.
"This new study delves into the cellular changes that mean our muscles aren’t just smaller but less effective – that 1 per cent annual hit to strength comes from a loss of only about 0.5 per cent of our muscle mass.
"Also, our skeletal muscles are, collectively, the largest tissue in our bodies. They’re responsible for secreting signalling molecules and absorbing sugar after a meal, among many other functions. So optimising our biggest tissue could play a critical role in other aspects of ageing such as inflammation and diabetes, as well as allowing us to climb the stairs."
How did the scientists create the atlas of ageing muscles? The scientists used advanced imaging and single-cell sequencing technology to analyse human skeletal muscle samples. These samples came from 17 donor adults, aged 20-75.
They discovered that the genes controlling ribosomes (which are responsible for producing proteins) were less active in the older participant’s muscle stem cells. This means that those aged cells cannot easily repair and regenerate muscle fibres.
The atlas also revealed new cell populations that explain why some muscle fibres age faster than others. It also deepened the scientists’ understanding of how muscles compensate for the effects of ageing.
We have two types of muscle fibres: ‘slow-twitch’, which help with endurance activity, and ‘fast-twitch’, for powerful, explosive bursts of movement. The researchers found that age makes us lose a key fast-twitch muscle fibre known as type IIx.
Yet our bodies make up for the loss by increasing fast-twitch characteristics within slow-twitch fibres, as well as increasing other fast-twitch fibres that remain. Our bodies also work to rebuild the connections between nerves and ageing muscles that have declined.
About our expert
Dr Andrew Steele is a scientist, writer and presenter. He is the author of Ageless: The New Science of Getting Older Without Getting Old. After completing a PhD in Physics, Steele decided to make the unusual leap to biology and has used computers to decode our DNA at the Francis Crick Institute in London.
Read more: