Due to a recent desire to perform HIIT workouts as often as twice a day to keep my endomorphic metabolism going, I got interested in the kettlebell. It seems to me that most HIIT workouts emphasize lower body movement, which if I do twice a day will be way too taxing. While I realize that even the basic kettlebell swing works the lower body, it's not nearly as dominant as say, sprinting or jump roping. This is the only thing that interests me regarding kettlebells. I do not wish to become a kettlebell master and I do not wish to grow stronger using kettlebell. I would rather use barbell or bodyweight training. This is another reason I am interested in kettlebell for HIIT, because I can't very well do HIIT pushups or something and expect to be at my best during my next strength training session. Kettlebell, on the other hand, seems like it wouldn't be that hard on the muscles so long as the weight wasn't too heavy. Anyway, my point is that I don't plan on buying multiple kettlebells or using the one I have for anything other than HIIT. So as a relatively fit male, which size should I get?