Study Reveals Mechanism Behind Age-Related Muscle Weakness

Nearly half of adults older than 80 are affected by sarcopenia, and new research suggests that failing communication between nerves and muscles may contribute to this age-related loss of strength.

Published in The Journal of Clinical Investigation, the study found that the neuromuscular junction, the point where nerves send signals to muscles, becomes less reliable with age. This may make it harder for muscle fibres to respond properly to nerve signals.

Researchers studied both humans and animal models and linked this decline to lower levels of a protein called NaV1.4. The protein helps muscle fibres respond to signals that tell them to contract.

For years, researchers have focused mainly on muscle loss and the decline of nerve cells as possible explanations for sarcopenia. The new findings suggest that the communication point between nerves and muscles may also be an important part of the problem.

The researchers then investigated whether this failure could be reversed. They targeted another protein, called ClC-1, using an approach developed in collaboration with an international biotechnology company.

In an animal model, partially blocking ClC-1 made ageing muscles more responsive to nerve signals and improved muscle strength. Unlike approaches that aim to replace lost muscle or nerve cells, this strategy attempts to improve the response of existing muscle fibres.

Researchers said the findings could eventually lead to treatments for older adults with sarcopenia, potentially helping preserve mobility and independence. However, the approach has so far shown benefits in animal models, and its effectiveness specifically for age-related sarcopenia in humans remains unproven.

Further clinical studies will be needed to determine whether targeting neuromuscular communication can safely improve muscle strength and function in older adults with sarcopenia.

REFERENCE: W. David Arnold, et al.; Neuromuscular junction failure in sarcopenia is linked to NaV1.4 loss and reversed by ClC-1 inhibition. Journal of Clinical Investigation, 2026; 136 (17) DOI: 10.1172/JCI190646