Hello,I’ll start again with HIIT, you already said that after training is better, but on leg day too?
Sorry, I don’t recall your previous question. Here’s my current recommendations for conditioning work at the bottom of this blog: http://tnation.t-nation.com/free_online_forum/diet_blog_hammer_velocity_shugart/running_makes_you_fat
Generally speaking, you shouldn’t do any fatiguing type of cardio or conditioning pre-weight-training if it’s enough to affect your performance on the weights. After may be better, and a separate session with a few hours in between even better. But with the type of conditioning I recommend in the link above, you can do it after lifting with no problem. That’s more convenient for most people anyway.
As for leg work, no, you would not want to do sprints after a tough leg workout. And if you could, then it probably means you held back on leg training or phoned it in. So, after leg training, you could do battle ropes, boxing, or any upper-body dominant form of brief, intense conditioning.