Board Thread:Naruto Discussions/@comment-33026485-20170904034338/@comment-32569165-20170904111136

Mr. Grave wrote:

In Chapter 500 of the manga, Kushina said and I quote: "I was born with very strong chakra, even for Uzushio, strong enough to control the Kyubi." This right here. Tsunade might have a very good chakra control and Senju bloodline, but that doesn't matter when it comes down to hosting a Tailed Beast, especially someone of the caliber of Kurama. His chakra is said to be very heavy, that's why someone with extraordinary stamina(Uzumaki trait) and powerful Chakra(Kushina in this case) is needed.