In this way, following denervation, an original fast-twitch fibre can become a slow-twitch fibre, which affects the functional integrity of the pelvic floor.
The velocity of muscle fibre contraction varies among the motor units: slow-twitch fibres, which generate less force, are recruited first.
Marathon runners have more slow-twitch fibres
, which is one of the reasons why you are never going to turn Paula Radcliffe into a great sprinter, or Usain Bolt into a good long-distance runner," Harridge said.
Researchers discovered the astronauts had lost more than 40 per cent of the power in the slow-twitch fibres
of their calf muscles - which control balance and posture.
Slow-twitch fibres are the ones that can perform for hours on end without fatigue as they convert oxygen, slowly, into energy.
Horses in general have a much higher percentage of fast-twitch than slow-twitch fibres in their make-up, and thoroughbreds have a greater percentage of fast-twitch fibres than many other breeds.
West Africans have a higher percentage of fast-twitch muscle fibres, while East Africans have more slow-twitch fibres
which helps endurance rather than pace.