Tiny Gains

Building muscle doesn’t just happen in the gym, where damage or hypertrophy recruits new muscle fibres to bulging biceps. During development, each of our muscle fibres must grow longer as the bones they’re attached to move further apart. But how? Here researchers use a combination of advanced microscopy and image analysis tool to spot patterns of stretchy regions called sarcomeres, highlighted between blue dots along these muscle fibres from fruit flies (Drosophila). The team discover that tension in the stretching fibres triggers muscle-building proteins to add new sarcomeres inside existing ones – a bit like tying elastic loom bands in the middle of a chain together to make a bracelet longer (although ~10,000 times smaller). Fruit flies share many of our genes, so these insights will help us to understand how our musculoskeletal system develops, ready to cope with press ups in later life.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Clement Rodier and colleagues
• CNRS, IBDM, Turing Centre for Living Systems, Aix Marseille University, Marseille, France
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Science Advances, July 2025