For decades, scientists believed that muscle fiber typology was mostly set at birth—some people were built for speed, others for endurance. However, a 2018 study led by Andrew Galpin of California ...

Everyone is familiar, at least hand-wavingly, with the distinction between slow-twitch and fast-twitch muscle-fiber types. The former are great for running marathons; the latter are ideal for ...

As people age, muscles naturally lose mass and strength, a condition known as sarcopenia. The decline can make everyday activities harder and increases the risk of falls, disability and early death.