MOTS-c: The Mitochondrial Peptide Researchers Linked to Exercise

MOTS-c has an unusual origin story. Its instructions are encoded in mitochondrial DNA. Mitochondria are the structures inside our cells that help turn the food we eat into usable energy. They also participate in cell signaling. MOTS-c gives researchers a way to explore how those two jobs might connect when we move. 1

What changed when people exercised?

In a small study, researchers took blood and muscle samples from healthy young men around a bout of cycling. They found that the body’s own MOTS-c increased after exercise. That observation gives researchers a specific signal to follow when they study how muscles respond to physical effort. It was a study of what the body made during exercise. The participants weren’t given MOTS-c to see whether it improved their fitness. 1

Another team, including researchers at Karolinska Institutet in Sweden, compared endurance exercise, resistance exercise, and rest. They measured mitochondrial peptides in blood and muscle at several times. That design matters because the kind of movement, the sample, and when it’s taken can affect what researchers see. A 2026 systematic review found nine studies on exercise and these peptides. It’s a growing area of research with room for more direct comparisons. 2 3

What was tested in mice?

The first paper also described separate experiments in which researchers gave MOTS-c to mice. Treated mice performed better on measures of physical capacity, including in older animals. The result is a useful reason to study how the peptide works. Whether an administered MOTS-c formulation improves endurance or metabolic health in people is a different question from either the mouse experiments or the human cycling measurements. 1

Three ways to read the next MOTS-c headline

1. Measured or given? Did the team measure MOTS-c the body already makes, or test an intervention?
2. Who took part? A mouse study and a small human exercise experiment answer different questions.
3. What changed? A short-term change in a blood sample is different from a sustained change in fitness, energy, or health.

This is one of the appealing things about following early science: a finding can be genuinely interesting before all the answers are in. How to Read a Peptide Study explains how a study’s design helps you tell which question it answered.