Digitally created image showing muscles of neck, chest and shoulder

Researchers gain new insight into how muscles work

The popular notion of how muscles function has been turned on its head with the publication of new and revealing ultrasound images.

Scientists have long believed that muscle fibres lie in straight lines. These new images, however, reveal that muscle fibres in fact buckle when they are shortened and at rest.

These ultrasound images of muscle fibres show the varying degrees
of waviness or ‘buckling’ when the leg muscles are shortened at rest

“This contradicts previously accepted models of how muscles work, and has never been observed before,” says Prof Simon Gandevia, a muscle function expert at Neuroscience Research Australia.

“This new understanding will allow us to build more accurate models of muscle function,” he says.

“It may also help us better understand conditions with poor muscle performance due to abnormalities in muscle length, such as spasticity in cerebral palsy and multiple sclerosis.”

The lead author of the study is Robert Herbert from the George Institute for Global Health.

The study was published in the Journal of Physiology.

Reference: Herbert RD, Clarke J, Kwah LK, Diong J, Martin J, Clarke EC, Bilston LE, Gandevia SC. In vivo passive mechanical behaviour of muscle fascicles and tendons in human gastrocnemius muscle-tendon units. J Physiol vol. 589 (issue 21), pp. 5257–5267