Health · Medical Research · 1 day ago
Aging muscles may trade power for protection as cardiolipin falls
Muscles contain fast-twitch fibers for powerful bursts and slow-twitch fibers for endurance.
In older mice, researchers found lower levels of cardiolipin, a fat that helps mitochondria produce energy.
When they reduced the enzyme that makes cardiolipin in young mice, their muscles shifted toward slow-twitch fibers and lost some powerful fibers.
The fibers also became smaller, and the mice’s grip strength fell.
The researchers say signals from damaged mitochondria may help trigger this shift, which could protect muscle from further damage even as it reduces strength.
An antioxidant that blocked the signal weakened the shift, but the muscles became smaller rather than healthier.
Samples from nine men showed that cardiolipin also declines with age in people, but the study did not establish that the same muscle changes happen in humans.
Researchers found that aging muscle in mice loses cardiolipin and shifts from powerful fast-twitch fibers toward slow-twitch fibers.
The shift may help protect muscle from damage linked to poorly working mitochondria.
Blocking the shift with an antioxidant weakened it in muscle cells grown in a dish.
When the team switched off the cardiolipin-producing enzyme in mice, their muscles shrank and adult mice lost grip strength.
Muscle samples from nine men showed that cardiolipin also declines with age, but did not establish that the other findings apply to people.
- Who
- Researchers led by Fabian Finger at the University of Copenhagen.
- What
- The study found that low cardiolipin was linked to a shift toward slow-twitch muscle fibers in mice.
- When
- Published October 10, 2026. The study compared 2-year-old mice with 9-week-old mice.
- Where
- The research was conducted almost entirely in mice; human muscle samples came from nine men.
- Why
- The researchers investigated why aging muscle shifts toward slow-twitch fibers and whether declining cardiolipin could cause that change.
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No direct quotes in the coverage so far.
Researchers switched off the gene for the enzyme that makes cardiolipin in muscle, and a fast muscle took on features of a slow one.
Adult mice that lost the gene had reduced grip strength.
Mice that lacked the gene from birth died, probably because their diaphragm was failing.
- Older mice
- 2 years old, compared with 9-week-old mice
- Human samples
- Five men aged 53 to 69 had less cardiolipin than four men aged 35 or younger
- Gene-affected mice
- 626 of 773 affected genes were controlled by ERRγ
- Adult mice
- Grip strength dropped within five weeks of losing the gene
Sources
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