Eccentric exercises such as these are designed to strengthen the muscle and tendon whilst it is in it's lengthening phase as opposed to shortening. This helps to improve control and build muscle AND TENDON. In this exercise, it is optimal to slowly control the band in its downwards phase to strengthen the hamstring muscles in the back of your thigh.
Demonstration and Instructions
Tie theraband around one ankle and one attached to the bottom of a sofa and lie on your front. Hook one leg under the band leg to assist the lift so both legs are doing equal work. Then let the unbanded leg go back down and slowly lower the band leg towards the ground and then hook under to repeat.
Special Notes
REGRESSION: You can increase the load on the unbanded leg to lighten the lifting load of the banded leg