Why Muscles Get Weak With Age and How Science Can Help

A team at the University of Missouri discovered a new reason why muscles get weaker as we grow older. This finding could lead to medicines that help seniors stay active and independent.

W. David Arnold, who runs the NextGen Precision Health program, and his coworkers noticed that the messages sent from nerves to muscles become less reliable with age. This problem may cause sarcopenia – the loss of muscle strength that affects almost half of people over 80.

The researchers also found a protein that might improve how old muscles react to nerve signals. This gives hope that part of the decline could be treated.

How Muscles Lose Strength

For many years, scientists have tried to explain why we get weaker as we age. Most studies looked at muscle loss or the death of nerve cells that control muscles.

Arnold thought the connection point between nerves and muscles might also be faulty.

He has spent more than ten years studying the neuromuscular junction – the tiny spot where a nerve tells a muscle to contract. Normally, this system works very well, letting electrical signals repeatedly make muscles move.

The new study shows that this reliability drops with age. Arnold’s team linked the drop to lower levels of a protein called NaV1.4, which helps muscles respond to nerve signals.

Can the Problem Be Fixed?

Finding the broken link gave the scientists a possible way to restore muscle function.

Working with NMD Pharma from Denmark, they used a method that partially blocks another protein, ClC‑1. In mice, this made old muscles respond better to nerve signals and increased strength.

Instead of adding new muscle or nerves, the approach makes the existing fibers react more strongly to the messages they receive.

From Lab to Medicine

There is already proof that blocking ClC‑1 can help people with other nerve‑muscle diseases. Arnold took part in a trial of ignaseclant, a drug that partially inhibits ClC‑1, in patients with Charcot‑Marie‑Tooth disease.

The trial showed improvements in strength and physical function. Arnold believes the drug could later be tested for sarcopenia in older adults.

Global Collaboration

The project brings together experts from the United States, Denmark, Scotland, Saudi Arabia, and India. Arnold’s team includes a specialist from Japan who added powerful imaging tools to the research.

The study, titled “Neuromuscular junction failure in sarcopenia is linked to NaV1.4 loss and reversed by ClC‑1 inhibition,” was published in The Journal of Clinical Investigation.