A long time ago, I ran Tren -A at 75mg/wk. Duringcardio (burpees and stair climber). I could barely breathe and each time Iinhaled I had to do one extra inhalation to feel like I filled up my lungs. I feltlike I was so close to passing out.
1. What causes the labored breathing when usingtren?

2. Is there a compound someone could substitute withthat will not have this effect on cardio for my next round?

I don't intend on using tren again, I'm just curious