Get back to running and improve your running with bounding!
According to an article by Powers 2010, “The external moments (force couples) created by the resultant ground reaction force (from the ground) are resisted internally by muscles and noncontractile tissues such as ligaments and the joint capsule.” This is referred to shock absorption, which happens over a period of time once the foot makes contact with the ground.
Active shock absorption happens during eccentric muscle contraction such as the hip and knee bending after it contacts the ground. Leg stiffness is inversely related to active shock absorption. However, leg stiffness is directly related to loading rate. So, the less the hip and knee bend at initial contact through stance, the faster passive structures including the hip and knee joints are compressed.
A study by Teng and Powers in 2015, concluded increasing trunk lean and hip flexion during running can decrease the energy absorbed at the knee. Here is a bounding exercise to promote active shock absorption with hip flexion. We want to maximize use of the gluteus maximus and active shock absorption by allowing the hip to flex during landing. The best cues to use are land softly and stay quiet! The less sound you make, likely the more active shock absorption you are doing!
Powers CM. The Influence of Abnormal Hip Mechanics on Knee Injury: A Biomechanical Perspective. J Orthop Sport Phys Ther. 2010;40(2):42–51.
Teng H-L, Powers CM. Influence of Trunk Posture on Lower Extremity Energetics during Running.