When you carry out an intense workout such as a lactate-stacker session and you pile up prodigious quantities of lactic acid in your blood, what happens to that lactic acid after your workout is over? Should you try to do things which facilitate lactic-acid removal?
In the world of running, the belief that the excess post workout lactic acid can do destructive things has been popular.
One well-accepted view has been that lactic acid percolates around muscle cells following a strenuous bout of running, damaging muscle membranes and making the fibers quite sore within 24 hours. Fearing the destructive power of lactic acid, one well-known coach even suggested that speed training should be confined to no more than six weeks in any major training cycle. If continued for longer than that, the coach contended, speed training, with its high lactic-acid build-ups, could seriously harm aerobic structures within muscle cells and diminish endurance capacity.
Of course, we now know that such precepts are pure poppycock. A more-scientific explanation of lactic-acid's fate has been that the controversial stuff was grabbed by the liver after a rough workout and then converted into glucose, which could be dribbled into the blood later, as needed, to maintain blood-glucose concentrations.
Although this scientific exegesis has been considerably more appealing than the lactic-acid-mayhem theory, we now know that it is also a bit off the mark. What really happens to lactic acid after you hang up your running shorts to dry? Pure and simple, most of the stuff is simply oxidized, i. e., broken down to water and carbon dioxide, with a consequent vast release of fuel for cellular processes. Your heart loves to see you do your lactate stackers, because it snacks on the resulting lactic acid at a feverish pitch after the workout is over. Your muscles, too, get into the act, using lactic acid at high rates, at least partially to kick-start the post-workout recovery process. It is now believed that 70 percent of the lactic acid which floods your blood after a spiky workout is oxidized; 20 percent is probably converted to glucose (which can then be used for glycogen formation), and-somewhat surprisingly to many-about 10 percent is utilized to make protein.
You may be surprised to learn that the blood-lactate clearance process can go on for a fairly long time after a demanding workout ends-and that some forms of exercise can actually speed the rate at which lactate disappears from the blood, while others do not.
For example, let's say you have just completed a lactate-stacker session (with one-minute work intervals at close to all-out intensity and two-minute, easy-jog recoveries in between). For your cool-down, you could just walk around and chat with your running friends who have similarly chastised themselves with the stacker session, or you could jog along-on well-worn legs-at a moderate intensity. Which form of recovery would cause your heart and muscles to clear lactic acid from the blood more readily?
If your blood-lactate levels reached about 12 millimoles per liter at the end of the session (a pretty reasonable guess for many runners) and you decided to jog along at a light intensity of around 40 percent of maximal aerobic capacity (perhaps 60 percent of max heart rate), your blood-lactate concentrations would commence a steady decline as soon as you began jogging and would be back at baseline levels within 45 minutes or so. In contrast, if you stood around and chatted, your blood lactate would still be elevated after 45 minutes, probably resting somewhere in the four to six millimoles per liter range (baseline is about two millimoles).
What is the reason for this? Light exercise increases the rate at which the heart and muscles oxidize lactic acid for fuel (this should make sense, since with light exercise you are forcing the heart and muscles to increase their work rate above resting levels). Thus, lactic acid disappears from the blood more quickly. Additional lactic acid does not pour into the blood, since your cool-down is so light in intensity. If you pushed the intensity needle up significantly during your cool-down, however, the story would probably be completely different, as the higher intensity might spew lactic acid into the blood's "pool" of the stuff. The bottom line, however, is that you don't really need to worry about lactic acid after your workout is over; your heart and muscles will take care of everything for you. You should cool down, of course, but the purposes of your cool down are to relax and reflect on the good work you have done, to ease your ticker back into normal-beating mode instead of subjecting it to an elevator drop, and to smooth your muscles' transition to the quiescent state which will follow the workout.
Looking to improve your running in 2010 running velocity at lactate threshold (RVLT) is one of the best predictors of performance at distances ranging from 800 meters to 100 kilometers, for runners of all ages and ability levels.
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