No bounce. So tight back got IT thx . I do it elbows on the floor, what counts as a plank? My workout is plank on elbows first like a push up then sideways , after that push ups ,crunches, supermen and sometimes end with air chair i did for 2 Weeks felt progress .6x times a week Sunday off afer 2 Weeks i should have made bigger sets but my lower back killed me so I stoped. What can I do instead od crunches?