O'Senseis Aikido is based on developing aiki in the body first then waza.He really did not teach anybody in that way.One needs to find someone who teaches aiki body building,if you want to understand O'Senseis Aikido.
O Sensei's Aikido is based on developing a grounded harmonically non-resistant Internal relationship with uke. The phrase Aiki in the body, as a thing in itself, implies Aiki can ever be independent or separate from uke. It can't. I believe the phrase really refers to nage's integrity, balance, and connection with nage's own center. I'll specify all of nage here as I've witnessed the resistive, independent, or 'dead' limb issue affecting both nage and uke.