Friday, February 10, 2012

Energy Systems

Most likely right now, you are doing aerobics.  That is to say, your body is fueling itself via oxygen powered energy production, hopefully, oxidation of fat.  Fat is the optimal fuel for your body.  It can power you, in theory, if trained for it, for a long, long walk or run.  You can run a long ways on fat because anyone running a long way should be doing - aerobics.

That everyone thinks of high carb drinks and pills for endurance running is a funny thing to consider.  Technically, you don't need carb replenishment to power endurance running, unless you are running in the anaerobic threshold, and thus burning sugar via glycolysis.  However, I think many runners eat so many carbs they lose their capacity for fat oxidation and are stuck in sugar town while they try to run their way to fitness and health.  In particular, if you exercise with the goal of better health, or better glycemic control, the last thing you want to do is burn up 250 kcal or so on a 20 minute run, and then knock back 250g of carbs in a "replenishment" or "recovery" drink.  Just skip both the run and the drink, you'll be better off walking.

For the record, you likely have something like 250g of glycogen stored in muscles, and another 70g stored in your liver.  Add that to the 5g of glucose dissolved in your blood, and the grand total is about 325g or so of sugar available to burn, which is about 1300kcal, which is about a third of the caloric energy available in a pound of fat.  So be you a 130 pound lady at 20% body fat, or a 175 pound man at 10% body fat, you have 6 to 10 times more kcal available as fat as you would have as sugar.

It hardly matters, as anyone who wants to could have figured out by now that spending hours a week doing high intensity aerobics is not the e-ticket to either fitness or health.  But - a few short runs a week sure beats watching TV, and running has the benefit of being cheap and accessible to almost anyone.  Thus, the point is, if you want those run sessions to translate into better health, knock if off with the goofy recovery drinks and love yourself some water, with potassium or salt as needed, like this:  Now Foods Potassium Gluconate Pure Powder, and maybe add a little of this for good measure:  NOW Foods ZMA.  Nope, they are not paleolithic, but since we're not eating whole animals any longer, compromise is pragmatic.

Fat is the body's preferred fuel for most functions, as evidenced by the fact that it is the fuel we are built to store.  One of the biggest benefits of the paleo prescription is that it restricts carbohydrate intake enough to require that the body regain the capacity for fat oxidation on a large scale.  Eat meat, vegetables, nuts and seeds, little fruit or starch, no sugar/wheat.

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