I have been doing a circut where i warm up walking on a treadmill then do 20 burpees, go back to walking for 90 seconds, do 18 burpees, walk 90 seconds then continue this progression till i get to sets of 10 burpees and continue this for a few more sets of 10. Could this be considered HIIT cardio instead of sprints? Also what are your thoughts on barbell complexes as cardio? Lastly any suggestions for good HIIT cardio methods not involving sprints. thank you in advance for comments and suggestions.