One interesting aspect of doing cardio is that the more you do, the less you get out of it. Sure, maybe you can run farther and faster, but that efficiency means you’re also burning fewer calories for each mile you put in. For people trying to lose weight or in a time crunch, this can be a frustrating part of getting fit. Curse you, biological efficiency and your diminishing returns.
In a recent article I looked at the impacts over time of different types of workouts on metabolism. I concluded that for serious trainees, longer workouts were better for cardio. But some of us only have a short time available to workout and instead rely on the “after-burn” post-workout effect of increased metabolism. So, what impact does getting more fit have on this particular post-workout effect?
One way to study the metabolic cost of exercise over time is by measuring something called excess post-exercise oxygen consumption (EPOC). EPOC has been a bit of a buzz-term over the last few years, as proponents of high EPOC-inducing workouts have come out of the woodwork, exaggerating its benefits or confusing the bottom line. Basically, it’s a measure of how much energy your body uses through how much oxygen it needs to maintain metabolism. Higher oxygen consumption means higher metabolism.
A recent study published by BioMed Central looked at the EPOC of an exercise group doing various types of cardio workouts. They used a distance workout, an intense interval workout, and a medium intensity interval workout. They then compared the EPOC to the existing fitness levels of each participant and found that the more intense the workout, the more significant effect an athlete’s fitness level will have on their EPOC. And that is to say, the more fit the participant was, the less EPOC they experienced for intense workouts. There wasn’t a big difference with the less intense workouts, but as we have seen before, these workouts don’t have as high an EPOC anyway.
Of course this is probably just a nail in the coffin for those pushing intense interval training as a superior method for weight loss over long distance workouts. The big advantage for interval programs is simply time savings and that something is better than nothing. However, for those willing to put the time in, long distance workouts not only have a greater total calorie cost, but as you get more and more fit, the benefits of a post-exercise metabolic boost are reduced in interval training but unchanged in long distance work. If you’re serious about your cardio or weight loss results, in most situations you’ll be better off with a longer workout unless you need to develop your anaerobic system for your sport.
Tomoaki Matsuo, et.al., “Cardiorespiratory fitness level correlates inversely with excess post-exercise oxygen consumption after aerobic-type interval training,” BMC Research Notes, 5:646 (2012)
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