The anatomical characteristics of the human body cause it to function in a crisscross manner. The arm-and-shoulder mechanism on one side links diagonally through the torso mechanism to the hip-and-leg mechanism on the opposite side.
Think about what you're doing while walking, running, punching, throwing, and batting. Such cross-body linkages are foundational to human functioning and a big part of athletic movement.
One type of cross-body movement involves rotational core exercises, such as weight-plate chops shown here.
Instead of using one dimensional thinking and throwing rocks by doing cyclical modes of cardio, why not try to cover as many needs as possible in a short period of time with a circuit of exercises?
If you've been around weight training for any length of time, you've probably read or tried an arm specialization routine. There are a bunch of these around with different cool names for what amounts to the same old shit: do a bunch of arm exercises. Yeah, the exercises change and the sets and reps change, but it still amounts to just doing more arm work.