HIIT and resistence exercise may not work well together

http://www.ncbi.nlm.nih.gov/pubmed/19692661

It seems performing HIIT style exercise before resistence exercise may interfere with the anabolic response of the resistence exercise.

Muscle biopsy was only taken 3 hours after exercise. But this study could be a good indication that if your attempt to build muscle, then go to the gym just for that. Dont do anything else there. Including HIIT. Keep that for another session.