Muscle length is a major determinant of eccentric exercise damage.

Background

• Muscle are damaged by eccentric exercise, ie forced lengthening of muscle while generating active tension.
• Eccentric exercise occurs when muscles are used as brakes, eg walking downhill.
• Damage is manifest as:
  • pain and tenderness next day.
  • reduced force.
  • histological damage.
  • biochemical markers.
  • shift in the length that is optimum for tension generation.
• Extent of damage is determined by:
  • previous usage.
  • level of muscle activation.
  • number and amplitude of stretches.
  • muscle length range involved in the stretch.