I recall doing pushups on a platform years ago. My personal trainer at the time was a proponent.
At first I thought your readers were asking you about the hand held massagers used for recovery. https://www.google.com/search?q=handheld+muscle+massager&rlz=1C1CHBF_enUS1001US1001&oq=hand+held+muscle&aqs=chrome.1.69i57j0i10i512l5j0i22i30l2j0i10i22i30j0i22i30.6997j1j15&sourceid=chrome&ie=UTF-8