hi i was at table tennis last night from 4:30pm till 9pm and played most of that time. i am of a athletic build and woke up this morning with 3 bruise's near the base of my spine by my bum 2 of them are on ether side just over hip meet's the back closest to the skin/spine and another bruise about 1/2 inch's above that on the right side. and the bruise's do not heart to touch just noticed them.