I hope not too off topic....
Some upper body workouts get my heart rate up too.
However, a side effect I occasionally get from lower body workouts are....shall we say....rather intense wood (the kind that makes you glad you're wearing a long shirt).
I suppose it's just the high BP doing it's thing with the elevated T, but it's almost embarasing....especially if a lady who's rather reserved about such things notices and then trys to act like she doesn't notice (you know the constant glancing at "it" while trying to talk about the weather).