This may be the case for Sakura...though she have developed Raw strength, but Tsunade is innately strong, and can obliterate the petra path with her pinky.
Sakura punches require chakra most of the times, but the pertra path can remotely absorb the attacks, he must make contact with the chakra in order to absorb it, seeing as how they release it upon and contact, with added force, I find it unlikely for him to absorb a punch,
Also they uses there first as a the weapon, so it isn't ninjutsu, because they are exactly releasing the chakra, but they are releases the force behind it.