I was reading a Jahlil Okafor interview earlier today that he did with GQ, where he was talking about his own training regimen and new diet he used to get in shape and they talked a little about Zion. Here's the article:
https://www.gq.com/story/real-life-diet-jahlil-okafor
Here's the stuff about Zion: ''When I went to Duke a couple weeks ago, I was talking to the strength coach. He said he didn’t want Zion to lift that much weight, because he’s so strong already. A lot of the things they did involved him just using his body weight to maintain his strength, rather than using heavy weights in a way that might change his body. ''
Basically, according to Okafor, Zion's been doing pretty much body-weight training only since going to Duke. Not much weight training at all.