in ultra endurance the slow twitch muscle fibres matter more, not the size of big muscles. https://www.bbc.com/news/world-49284389 https://www.bbc.com/news/worl

in ultra endurance the slow twitch muscle fibres matter more, not the size of big muscles. https://www.bbc.com/news/world-49284389 https://www.bbc.com/news/world-49284389 there have been quite a few articles lately explaining the situation