[Todd Struble]

If I’m spending a lot of time with a high heartrate, I would include it in my 80/20 volume.  It’s hard to say without knowing exactly what your workout entails, but I know Scott tells an anecdote about a crossfit gym owner having a very poor aerobic base due to all the high intensity work.  If it’s more like lifting heavy things for a few reps with lots of long recoveries in between sets, then I personally would treat it like a strength workout and not include it.

Your body doesn’t know if you’re doing high intensity in a group session or by yourself on the track in perfectly prescribed intervals – it’s fatigue.  I think the general advice is, cross training will fatigue you but not provide you with sport-specific stimulus and thus it is not optimal for training purposes.  From p. 99-100 of TftUA, there’s a role for low impact cross training as recovery work like swimming or cycling to give your joints a break from the pounding, but in general its better to be sport specific.

That being said, (my personal perspective), if you are willing to sacrifice optimal, I think there’s a lot to be said for doing things you love, whether it’s for the social aspect or simply for fun.  If it makes you happy and keeps the stoke high, it might be more sustainable in the long term to sacrifice optimal.  I like playing rec soccer – same deal, it’s social and high intensity (and higher injury risk).  I gave it up for a flat marathon training cycle, but now I’m back at it (after easing sloooooowly back in).  If and when I pick another race or goal that I really wanted to put all of my energy into, I’ll likely have to give it up again.  But I’d be a bit resentful of running if it meant I couldn’t play another team sport ever again.