Self-Inflicted Zenkais

[Kamiccolo9]

On the way to Namek, Goku trains by hitting himself with Kamehamehas and taking advantage of the zenkais offered by recovering from his injuries. But later, during the Freeza fight, Vegeta has to get Krillin to injure him. Why couldn't he do it himself?

[Saiyan Prince Vegeta]

Maybe they can't generate enough ki to nearly kill themselves, but Gokus exhaustion from training in intense gravity coupled with him inflicting damage on him self tipped the scales enough to give a Zenkai. It could also be that his level dropped that much that he may not have been able to handle 10g, so I guess you could say the gravity was crushing him aswell. Then there's a flaw with that, and that is Vegeta could have used a blast like Goku, re-directed it at himself, let go of it, and then drop his defenses and let it him. So I really don't know, maybe he was panicked and wasn't thinking.

[Kamiccolo9]

Maybe they can't generate enough ki to nearly kill themselves, but Gokus exhaustion from training in intense gravity coupled with him inflicting damage on him self tipped the scales enough to give a Zenkai. It could also be that his level dropped that much that he may not have been able to handle 10g, so I guess you could say the gravity was crushing him aswell. Then there's a flaw with that, and that is Vegeta could have used a blast like Goku, re-directed it at himself, let go of it, and then drop his defenses and let it him. So I really don't know, maybe he was panicked and wasn't thinking.

Well, admittedly he's not a Saiyan, but Ginyu punched a hole in his own chest. I'm pretty sure that would count as a near death wound. But I agree with you, the only explanation I can think of is that he panicked.

[Tyro]

I don't think Goku "took advantage of" zenkais. The narrator states that he's definitely getting them from his training, but as far as Goku knows the senzu beans are only healing his damage, hunger, and fatigue, and that he's getting stronger precisely because of his training. I also don't think that he meant to hurt himself to the point of near-death with the Kamehameha, but that it was just general training to toughen his body. Funny, I've never read those pages to mean that Goku was purposely hurting himself to zenkai-up, as it were. I just don't think it's implied.

As far as I remember the only time he acknowledged getting a zenkai was after healing in the recovery pod, and maaaybe when he said "guess all that fighting with Vegeta wasn't for nothing."

[Saiyan Prince Vegeta]

He most definetly isn't doing it by purpose IMO. He's just testing his limits, but with Goku being a Saiyan pushing past his limits gives him a Zenkai.

[the_abberration]

Maybe they can't generate enough ki to nearly kill themselves, but Gokus exhaustion from training in intense gravity coupled with him inflicting damage on him self tipped the scales enough to give a Zenkai. It could also be that his level dropped that much that he may not have been able to handle 10g, so I guess you could say the gravity was crushing him as well.

I agree with this logic. The gravity was probably already killing Goku. Add his exerting himself on top of it, and he was most likely near death before he took a senzu. Similar to a human having a fatal gunshot wound continuing to fight, and getting healed just before he dies perhaps??

Then there's a flaw with that, and that is Vegeta could have used a blast like Goku, re-directed it at himself, let go of it, and then drop his defenses and let it him. So I really don't know, maybe he was panicked and wasn't thinking.

Not so much a flaw, if you consider each were operating on opposite ends of self preservation or "fight or flight instinct". Goku was willing to go to the extreme of attacking himself at full power (not thinking about or trying to kill himself mind you, but to get the full benefit of self training), whereas Vegeta would hold back and not use full power out of fear that he would kill himself. Also, Vegeta may not have time to set up a redirected ki blast in the middle of the fight (if he thought about something like that to begin with).

[hleV]

A simple explanation would be that Vegeta didn't know whether it would work if he injured himself and didn't want to risk.
Another theory is that he couldn't injure himself so easily - if he lowered his power, his attacks would be weaker as well.

[Darkprince410]

I think as far as Vegeta's case vs. Ginyu's case, Vegeta needed a severe, immediately life-threatening attack to give him the potent enough Zenkai. With Ginyu, while the attack might eventually be fatal (even if not, it was debilitating for Goku), he was able to go around for a good while.