Inclusion Criteria:  18 - 30 years  Exclusion Criteria:  Currently doing resistance exercise > 3 times per month or aerobic exercise at or more than 30 min, 5 days per week. Any lower limb injuries or surgery within a year of the study If any of the subject's are too tall for the Eccentron machine (>76 inches tall) If any of the subject's eccentric strength is measured to be greater than 725 pounds during the first test of eccentric strength.