[Scott Johnston]

Thanks for the kind words!!  Great question too.

Yes, the aerobic base training needs to be muscle-specific to be most effective.  How do you build an aerobic base in the upper body musculature?  Well, swimmers and cross-country skiers do it by a high volume of aerobic work with the arms/chest.   That’s a big ask for most people though. Here is something you might try rather than doing thousands of pushups each day. I have used this with many military athletes who have to be able to do a high number of push-ups in 2 minutes.  I put them in a Max Strength program with push-ups. Low volume but high resistance.  They use weight vests and also weight plates on their backs.  Doing sets of 5-4-3-2-1 with increasing weight from 85-100% of 1RM.  They can know out 5060 in 2 minutes. IN your case you cold then rest in the pus-up plank between sets of 10-20.  I think you could do this for sure.

Scott