Type IIA muscle fibres

1. Endurance training increases type IIA muscle fibres in rats (near to 70%).

   “percentage of type IIA fibres increased from a mean value of below 40% in one-month-old rats to above 50% in the untrained and near to 70% in the trained rats at the age of 24 months.”

   Animalslife-long endurance trainingrectus femoris muscle

   Effects of ageing and physical training on rat skeletal muscle. An experimental study on the properties of collagen, laminin, and fibre types in muscles serving different functions

   Acta physiologica Scandinavica. Supplementum·1 Jan 1989

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