User blog:UnseenBurstWBO/Why didn't Deku break his Legs when he used One For All to jump upwards when he was Training while Gran Tornio was sleeping

I'm very curious to know the answer since I thought the only way Deku could use 5% of his Power was if he was using Full Cowling and spread it evenly throughout his body. Is he able to use 5% without Full Cowling activated or am I just missing something?