At Adidas store in Sanlitum area in Beijing, you can this test yourself.
They give you two similar balls and on the ground two kind of foam; normal one and the one used in Adidas shoes, you actually see the difference
The normal one: it bounces two or three times max before the foam completely absorbs the shock
The Adidas: it keep bouncing a lot more than the other one which means in the real life it reduces the shock on your knees by keeping you bouncing more