Thursday, February 3, 2011

20 Minutes of Cardio - Not

Many folks have so ingrained the idea that "cardio" is helpful to body composition management that they want to add that "20 minutes of cardio" to any short, hard workout they may do.  They have associated the "cardio" to being lean, or feeling good, or it's a remnant from so many years of disciplined training, even when it provided minimal results.  And very few folks get more than minimal results for 20 minutes of cardio.  Why would I say that?  


First off, think of what adaptations are demanded by that 20 minutes of "cardio".  


There's a demand for efficiency above all else - less effort for more distance.  If you demand efficiency at low intensity over a long duration, you are demanding that your body be lighter and less muscular - and the farther you take that kind of training, the less muscle you will have, until you look like one of the emaciated dogs who rule the endurance world.  That kind of training will demand competency in the oxidative energy pathway only.  In short, you are asking your body to make itself light, efficient, and low powered.  You are cultivating the ability to produce less than 40% of your total power for a longish time - in other words, you are specializing in "not working very hard".  This is certainly better than nothing, but what other options are there?


You could spend the same 20 minutes running sprint intervals, or for that matter, only ten minutes, with a 3 or 4 to one work rest ratio, and you will demand that your body provide more power - the ability to do more work in less time - and you will demand competency in both the oxidative (aka aerobic) and glycolytic (aka anaerobic) energy pathways.  Of the two, glycolytic competency is more applicable to more sports, and more emergencies, than is oxidative competency.  If you engage interval work with sufficient intensity, you will begin to look more like the 800m athlete, lean but strong, and the 100m athlete, muscular, athletic, and powerful.


Aerobic work is significantly more efficient than anaerobic work - reportedly, 5 to 1 more fuel is burned for time under load doing sprints.  If you think exercise is important for weight loss, then you have five times as many reasons to be doing sprints - or maybe 9 times as many reasons, because metabolically speaking, when you stop the cardio session, your increased fuel burn also stops.  When you stop anaerobics, your body will 'benefit' from up to 9 hours of accelerated BMR (basal metabolic rate).  


My advice - build the intensity of your training over time so that you can drive yourself to complete exhaustion without over-work or injury in only a few minutes.  Think of "intense" as "a lot of work, quickly".  Some days, wreck yourself in under five minutes.  Some days go ten.  On rare occasions, see what it's like to do anaerobic workloads for 20 minutes.  If you feel like you need another 20 minutes of "cardio" after that, you should save that motive and energy for the next day when you push yourself harder for a shorter, more pain inducing workout.  On the other hand, if you feel nauseated, your option - push it and puke, or back off and finish at lower intensity.  Either way, you are getting fitter.

One example, of an infinite number of options, of a beginner high intensity WOD:  run as far as you can in 60s, rest for 2 minutes, repeat 2-3 times.  Drop a bean bag at the 60s point, and start your next run where you dropped the bag; measure how far you went in four minutes.  Repeat after 30 days to measure you improved anaerobic work capacity.  Make up, or find from CrossFit.com (or here:  No/Low Equipment WODs), other high intensity WODs, and work up a lather 3 to 4 days per week.

Another example:  10 pushups, 10 situps, run 200m, repeat for 8-15 minutes, record the workout duration and how many rounds you complete.

I know of no metric in which aerobic/endurance work provides more benefit than anaerobic work, and it generally take more time - but it does hurt less, which is my guess for why virtually no one does anaerobic work.  (Perversely, the vast majority of all studies of human health and performance are built around endurance work.)  The only reason I can think of to do aerobics is if you like to workout that way, if you want to be a competitive endurance athlete in spite of the small payback in health and fitness, or your job demands that you be able to "not work very hard" for a long, long time.

Go hard, go short.  Intensity trumps duration.

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