Cardiovascular training of this nature is good for two things 1) improving the efficiency of the aerobic energy system 2) regeneration and recovery through increased blood flow to muscles. But it is a grossly ineffective and utterly inefficient method for altering body composition. It has been proven time and time again that steady-state cardio does not hold a candle to interval training for improving body composition.
The most groundbreaking study to support this claim probably would have to come in the form of a 1994 study performed by Tremblay et. al that specifically was examining the effects of exercise intensity on body fatness and skeletal muscle metabolism. The study pitted fifteen weeks of endurance training verse fifteen weeks of interval training. The energy cost of the endurance training was whooping 28,661 calories while the energy cost of the interval training was less than half of that at 13,614 calories. Now when energy cost differences are accounted for in order to compare the two methods at the end of the study the interval group lost nine times more subcutaneous fat than the endurance training group. Do you need me to say it again NINE TIMES MORE. So to recap the interval training group spent less time and energy than the endurance group yet got nine times the results. If that isn't efficient I don't know what is folks. This study by far solidifies the fact that if your goal is to lose fat and lots of it interval training is a far better tool to have in your arsenal than forty five minutes of half assed stair climbing and watching the latest jersey shore episode on tv. And if your not a fan of the scientific literature and need some real world application to back it up just take one quick look at a sprinter and a look at a marathoner now you tell me which one of their bodies you'd rather have. Let me give you a hint about this choice one does constant high intensity intervals without even planning it that way the other performs hours and hours of aerobic training in order to strength the maximal stroke of the heart and improve performance. The question is which one of these athletes and their training styles produce the best physiques?
The take away here people is you can spend less time at the gym and get greater results. Deciding to do cardio after a strength training session does not have to be a death sentence and it does not have to be a life long commitment. High intensity and short duration will always take you further in the game of fat-loss. Remember less is more!!!!!!!!
If you are wondering why interval training is more effective then you probably would be better served picking up a great exercise physiology txt book and really drilling the science itself because it goes a tad beyond most understanding. But essentially it comes down to EPOC or exercise post-oxygen consumption which will be highly elevated following interval training than following long term steady state cardio. Anyways this goes beyond the scope of this post. just remember always interval never stay steady.