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Fast Twitch, Slow Twitch; 1 in 5 People Have Mutant Gene To Better Tolerate Cold Temperatures
Almost one in five people lacks the protein α-actinin-3 in their muscle fibre. Researchers at Karolinska Institutet now show that more of the skeletal muscle of these individuals comprises slow-twitch muscle fibres, which are more durable and energy-efficient and provide better tolerance to low temperatures than fast-twitch muscle fibres. The results are published in The American Journal of Human Genetics.
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Skeletal muscle comprises fast-twitch (white) fibres that fatigue quickly and slow-twitch (red) fibres that are more resistant to fatigue. The protein α-actinin-3, which is found only in fast-twitch fibres, is absent in almost 20 per cent of people – almost 1.5 billion individuals – due to a mutation in the gene that codes for it. In evolutionary terms, the presence of the mutated gene increased when humans migrated from Af
Researchers at Karolinska Institutet in Sweden had 32 healthy men aged 18 to 40 sit in 14 degrees Celsius water until their body temperature dropped to 35.5C.
Researchers at Karolinska Institutet in Sweden had 32 healthy men aged 18 to 40 sit in 14 degrees Celsius water until their body temperature dropped to 35.5C.