In part 1 of our series on cardio and HIIT training we looked at the most commonly stated benefits and costs associated with each form of training. We should add this was done purely from the standpoint of looking at their relative impact on body composition rather than on their effects on aerobic or anaerobic performance.
In part 2 we looked at the commonly held belief that interval training is superior to steady state cardio by virtue of the EPOC or “afterburn” effect which its advocates proclaim as the reason for the superiority of HIIT. Upon closer examination the extra calories burned post exercise from HIIT are only slightly more than in regular cardio. Once adjusted for the fact that steady state cardio can be performed more frequently and for longer than intervals can, the weekly EPOC generated via steady state cardio is likely to be greater than that generated via interval training.
One thing that splits opinion among the athletic trainers is whether or not one or both of these forms of cardio are more likely to lead to muscle loss. While the popular argument, stated in part 1 of the series stated that aerobic training is more likely to lead to muscle loss while HIIT is better by virtue of it being a high intensity form of exercise, does this hold up in practice?
Marathon Runners Versus Sprinters
It is often said and repeated on bodybuilding discussion groups online that cardio will cause muscle tissue loss while HIIT will magically target fat stores only and, potentially even cause some muscle gain. To support this argument you will often see the commonly used strawman argument that marathon runners look like starving refugees while sprinters look like Greek gods. To the common man this is a pretty good argument for using HIIT since we would all rather look like sprinters as opposed to marathon runners.
The problem with this particular line of attack against steady state cardio is it is a gross misrepresentation of both the form of cardio used by bodybuilders as well as the type of interval training conducted by sprinters. The average bodybuilder looking to drop a little fat may be looking at performing 30-60mins of cardio only and does this in conjunction with a resistance training program. By contrast, the average endurance athlete will perform several hours worth of aerobic training per day and tend to perform ZERO resistance training. Therefore, saying the physiques of endurance athletes is the destiny of any bodybuilder who dares to use steady state cardio is a gross exaggeration of the actual training methods used by both. This is to say nothing of the differences in phenotype, nutrition, and use of ergogenics between these two populations.
Similarly, those who make the strongest case for HIIT training misrepresent the actual training done by elite sprinters. If we look at the typical HIIT programs being run they tend to employ a work to rest time of 1:1 with some, including the famous Tabata protocol, employing a work to rest ratio of 2:1. This is very demanding training without a doubt.
By contrast elite sprinters in the 100m will typically sprint at a maximal pace for no longer than 100-150m which means their work times will be around 10-15 secs. After such an effort they will typically rest for up to 15 minutes between sets. That means that for a 10 sec sprint their work to rest time would be 1:90! This is much closer to powerlifting for 1-3 reps than it is to anything resembling bodybuilding training or HIIT as practiced by bodybuilders. If not a 100m runner then how about a 400m runner you say? Well, again no. A 400m runner is required to have speed, anaerobic endurance as well as a great base of aerobic endurance to last such a long distance. This means that the training of a 400m runner, while resembling that of a short distance sprinter has a much bigger component of relatively long distance runs of between 300-800m typically. While these kinds of distances are more similar to the ones we see in HIIT the difference with a 400m runner is that contrary to what you may believe, the vast majority of this work is performed at sub-maximal intensity. Michael Johnson, the world 400m record holder, was known to run for over 20 minutes in his off season to help build his aerobic endurance. In addition, to make you understand the difference between HIIT as practiced by bodybuilders (balls to the wall where you bust a gut throughout) and the 400m, see the quote from Johnson below:
“The 400m is much harder to pace (than the 200) since nobody can go out and run 400 meters full-speed from the gun.”
If HIIT is a superior form of training as its advocates claim they had better come up with a different argument to this one.