Now that I’m a regular at the gym, coming up on a year, I am quite comfortable concluding that the "cardio craze" is complete bunk. It’s of virtually no value whatsoever, and the downsides far outweigh any advantages. I’d love it if my gym — which is a 5-minute walk, so I’m not about to switch — would dump all but a few of the cardio machines that take up enormous space, and use the space for crossfit training.
How did I come to this conclusion? Well, Art’s essay on Evolutionary Fitness (PDF) clued me in and made me aware, so it was in my field of view and I’ve observed.
The adaptive and variable energy demands of our ancestral existence are gone. We live a low energy ﬂux and metabolically unvaried existence in bodies designed for another lifeway. We are hunter/gatherers in pin-stripe suits, living a sedentary life and it is killing us in ways our ancestors never experienced. Virtually all the degenerative diseases–atherosclerosis, diabetes, high blood pressure, osteoporosis, declining muscle mass–of modern civilization are unheard of among hunter-gatherers and were not part of our ancestral experience. Most modern ﬁtness prescriptions are static and agricultural. These programs model the body as a machine, not as an adaptive organism. Consequently, they prescribe a regime in which the body is under-fed and over-trained. They are not based on adaptation, but on steady state analysis. These models assume the body is a linear process that maintains a steady state. In fact, all bodily processes are highly non-linear and these non-linearities must be exploited in any effective ﬁtness program. The key to exploiting the highly non-linear and dynamic adaptive metabolic processes of the human body is to achieve the right mixture of intensity and variety of activities.
Here is an example of the Zen-like twists that adaptive, non-linear systems like human metabolism follow that confound mechanistic thinking. The body uses fat in the aerobic (ST and lower IT) zone. So, linear thinking suggests that to burn fat you should operate in that zone. It would not surprise someone trained to understand the adaptive capabilities of the human body that if you burn more fat the body will ﬁnd a way to produce more. And this is just what happens when you energy ﬂows over the aerobic pathway—your body releases hormone messengers that signal higher fat production.
You do burn a higher proportion of calories as fat in the aerobic zone, but that is no reason to stay there. You burn more calories and more fat in total when you train at high intensity. And you do not open the metabolic pathways that cause your body to make more fat. Energy that ﬂows over the anaerobic pathway signals your body to make more muscle and to burn fat.
You incur an oxygen depth that raises metabolism for days after a high intensity session. Above all, you bring adaptations that burn fat. As the body remodels in response to the adaptive challenge presented by a brief, high-intensity session, it preferentially burns fat. In addition, you put on lean muscle mass that burns energy continuously. From 60 to 70 per cent of the energy you burn is at your basal metabolic rate. If you gain lean muscle mass you raise your basal metabolic rate and, thus, burn more energy 24 hours a day.
(I know I’ve mentioned and linked to this essay before, but presuming your interest, if you haven’t taken the time to to read it, you should — and I’m reading it for the third time.)
Anyway, long story short, I’ve seen amazing things in the gym. I see these same people, toiling away on the treadmill, day after day, week after week, month after month and they look like zombies to me. Far from the picture of health, they look highly stressed, swollen from body-wide inflammation, pale — awful. And they make no noticeable gains. On the other hand, a number of people have come up to me and complimented me on the gains I’ve made and they’ve noticed. I work out, high intensity, for a total of one hour per week — some do that every day on the treadmill or elliptical.
All that, to get to this: here’s a couple of posts my Mark Sisson, a former long-distance runner, covering the cardio-aerobic myth.
As Art says he feels like saying when he sees joggers on the street: "slow down and live longer."