ok so this is just a theory I'm throwing out there for guys to think about. I've done no direct research on this.
But I'm thinking that doing HIIT cardio while blasting large amounts of gear is not a very good idea for heart health.
With the recent passing of Matt Porter at only 34 years old with heart conditions, who used to do upwards of 3 HIIT cardio sessions per day and was a huge proponent of HIIT,, its crossed my mind.
so real quick, what is HIIT cardio. its high intensity interval training cardio. so think doing sprints on a track, you sprint hard as hell for one minute straight, then jog for 2 mins, then sprint again, etc. (Matt used to run stairs at a stadium)
so why wouldn't this be good for your heart while on gear? your probably increasing your chances of cardiac hypertrophy by 10 fold by doing this. Plus the fact that the gear your taking has your blood volume way way higher and thicker then normal (your probably also holding lots more muscle and water) and your heart is working twice as hard as it would if you were natty and had natural levels of blood volume.
heck natural athletes who engage in high intensity cardio sessions or sporting events quite often are already prone to getting cardiac hypertrophy. now you add a bodybuilder doing the same type of thing while on massive amounts of gear, add in HGH and Slin on top of that, elevated IGF levels, etc.. and your heart is no doubt going to enlarge.
I just think HIIT cardio , or any super high intensity cardio while on massive amounts of gear (with all the above listed extra blood volume and heart stress) is NOT a good idea or healthy for your heart at all.
steady state cardio is the heart healthier choice imo, especially when on gear
and on a side note. if your doing HIIT for fat burning. Keep in mind that HITT is way way more of a glycoletic (glycogen dependent) form of cardio anyhow. it uses up a ton of glycogen stores, not fat stores. the reason is because there is a lot more muscular contraction and explosiveness that goes on when your doing a sprint or high intensity form of cardio.. this requires glycogen for energy, not fat.. oxidizing fat for energy is a much more slow steady non muscular dependent energy source. when doing steady state cardio and not using a ton of explosive muscular contractions your body can better utilize fat for energy and not be so glycogen dependent (of course if your trying to purposely deplete glycogen stores, HIIT makes sense over steady state).
anyhow, this is just a thought and an opinion