Updated: 11/3/2020

Storyboard Text

  • Jack trains hard for his boxing match by doing box jumps, his favorite plyometric exercise.
  • The quadricep and calf muscles, as well as the hip extensors, are rapidly stretched, followed immediately by a concentric contraction of the same muscles.
  • While performing a plyometric movement, the muscle spindle fibers are the primary sensory mechanism for triggering a powerful concentric contraction.
  • When a muscle's fibers are rapidly stretched, the muscle spindle sends an afferent or sensory signal to the spinal cord. An efferent or motor signal is triggered to concentrically contract the fibers of the same muscle.
  • Sensory neurons typically have a short axon and long dendrite. They carry messages from sensory receptors to the CNS. This is the afferent division of the peripheral nervous system.
  • Information travels along interneurons. Interneurons connect neurons to one another. Their job is to pass information along since they do not have any motor or sensory functions.