This study evaluates the changes in muscles and tendons in the lower limb after an intervention of fatigue during 3 consecutive days between trained or not healthy subjects. One of the 2 groups received training by eccentric overload previously.

Changes in muscle and tendon tissues, due to exercise, could determine in the future the possibility of an injury. Understand the changes in the mechanical tissues is a key tool for prevention.

The evaluation of the thickness and area in tendons, the existence of new vessels within the tendon, muscle pennation angle or thermography are tools that have been widely used to detect these changes.

Running is one of the activities that can cause more muscle-tendon injuries, specially overuse injuries. However, the eccentric exercise suggest to make some adaptations in different tissues that may be beneficial to prevent damage after exercise.

Inclusion Criteria:

• Healthy subjects that performs any sport usually
• Subjects that never have made eccentric training will be included.
• Subjects must be willing to perform the procedure
• Sign informed consent

Exclusion Criteria:

• Subjects enrolled with lower limb pathology in last 6 months
• Subjects that don´t complete all the procedure will be excluded.