Which fiber type would be the most useful in the leg muscles of a long distance runner?
Slow Oxidative (SO) fibers are best for extended energy use and repetitive muscle contractions. These fibers are best for long distance runners like cross country athletes.
The three basic muscle fiber types are Fast Glycolytic (FG), Slow Oxidative (SO) and Fast Oxidative Glycolytic (FOG).
Each of these fiber types differ speed of muscle twitch and the use of energy available in the tissue.
FG fibers are fast twitch muscle fibers that have very explosive contractions and sustain energy for a limited period of time. These muscle fibers are best for short burst of energy activities like short distance races like the 100 meter sprint.
SO fibers are best for extended energy use and repetitive muscle contractions. These fibers are best for long distance runners like cross country athletes.
FOG fibers combine fast twitch fibers with extended energy use. These fibers are explosive and can sustain the energy level over a greater period of time. These muscle fiber types are best associated with athletes who compete in sports like soccer or basketball.