This study utilized HIIT sprinting instead of steady state cardio for the endurance component of the concurrent training group. The concurrent group made similar strength gains to the strength only group while making better endurance gains! Using interval training may be the best way to add cardio to a strength or bodybuilding program. Try intervals at 10-20 seconds on and 20-40 seconds off to start then manipulate your work: rest ratios to continue progressing.
Reference: Balabinis, C. P., Psarakis, C. H., Moukas, M., Vassiliou, M. P., & Behrakis, P. K. (2003). Early phase changes by concurrent endurance and strength training. Journal of Strength and Conditioning Research, 17(2), 393-401.