Off season training

What do you guys suggest a high jumper do during off season?
I am mainly focusing on flexibility, strength.

About once or twice a week, I will do plyos, starting off lightly and building my base. Sicne the season ended, I am probably at my strongest right now, but endurance is down. i added a bunch of lower body lifts on an organized routine, and it feels great. I added leg extensions which are amazing, I have to get new boxers because they dont fit anymore. Leg extensions are amazing…

Just wanted to hear what other high jumpers are doing…

Keeping in mind, I am not a high jumper, but I play volleyball with a college level high jumper. Man can he get up. Anyway, I asked him the same question you just asked and I will relay what he told me. Squats are something he does. He also does box jumps (I think that is what he called them). You know, jump up on a box and jump off and jump in the air again. I have just started to do these and I am using my bench. It is a quality bench and I wouldn’t use a crappy one. One of his coaches does Olympic lifts. He says he doesn’t do them however. Wish I could jump like this guy. I am 6’2" and could dunk a basketball two hands (woopie), but this guy is something else.

He mentioned some other stuff, but this seems to be the main thing.