Muscle length is a major determinant of eccentric exercise damage.

Previous observations

• Warren et al (1993) using rat soleus muscles
  • Took optimum as middle of physiological range.
  • Measured damage by force drop at optimum length.
  • Changed length by 5%.
  • They also changed stimulation rate.
  • Found strongest correlation with initial total tension, none with length.
• Newham et al (1988) using human elbow flexors.
  • Changed length by changing elbow and shoulder.
  • Assumed constant lever arm at elbow.
  • Found more damage at longer length, despite smaller torque.
• Morgan (1990) predicted that damage will only occur on the descending limb of the length-tension curve.