The reason for more upper body definition is three-fold, I think. And the reasons are:
1. Daily handstands, with attempts at handstand pushups.
2. Daily ring work (did I tell you we got rings???). They're in the garage right next to my car, and I either swing on them (hard, but fun) or do "skin the cats" (remember those?) or do reverse pushups, or (drum roll, please) just jump to support and hold there. The first time I did it, my body shook like I was having a seizure. Now I can stay there for a good, oh say 5 or 6 seconds before I have to jump down. I already respected my gymnast sons, but when you actually try something they do -- oh boy!
3. Cardio Coach -- Sean O'Malley rocks!