What you described was the effects of the Rasenshuriken if it hit an opponent. The move actually damages the muscle tissue of the user, thus making it dangerous to use.
That page speaks volumes about what sage mode can do. He fell from a very high distance, onto sharp spires and didnt get hurt, at all. Meaning the damage any normal human wouldve taken was voided due to sage mode. Even the frog remarks that your body is "activated" in many ways on the next page.
This page also sheds a little light on it. He needs to keep practicing in sage mode specifically which to me indicates that it is a jutsu that he couldnt do at one point, but now that he has sage mode he can accomplish that move without the ill effects.