Bounding is a common deficiency seen in distance runners.
In endurance running we want all our energy to go to pushing us forward. Bounding is when we are spending too much of the energy to move up and down, rather than forward.
Bounding can lead to or cause many of the "itis's"; patellar tendinitis, achilles tendinitis, etc. But it, as well as a few other things, can also cause women to have some leaking while running.
Even if you are not a mother, or don't have this problem. . . . You may know someone who needs these - please share!