Single leg lower body, single leg upper body!
For many of us, doing things on two legs comes pretty natural, like jumping, squatting, etc. But to build that "real world functional strength", sometimes you gotta go with the single leg. And when it comes to using the single leg, it can be actions done for the lower AND upper body.
In the video above, I perform a reverse barbell lunge, utilizing single leg strength. This forces one leg to be the "worker leg". Then I switch.
I take a similar approach to training my upper body on one leg. I take a knee and perform an overhead DB pressing movement. Being on one knee forces my body to stabilize and stay upright as I use my core and tighten it to get the single DB pressed above my head.
There you have it! Use single leg action, to create training for your upper and lower body.