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August 16, 2011
 
GET YOUR LACTATE-THRESHOLD SPEED IN 30 MINUTES

       As my youngest daughter Sabrina might say, there are at least 30 kabillion ways to estimate your lactate threshold. Some of them are even accurate.


      Your running sped at lactate threshold is, of course, something to be concerned about. After all, various studies have suggested that lactate-threshold speed is the best predictor of endurance performance (1 & 2). Lactate-threshold velocity is simply the speed above which lactate begins to accumulate rather dramatically in the blood. It works as an endurance-event predictor because lactate is a key fuel, much-preferred by the muscles, and pile-ups in the blood indicates that the muscles lack the machinery necessary to process lactate at high rates (a bad thing, since lactate is such an important source of energy).


      Because lacatate threshold is important and it can be estimated in various ways, many coaches and training books prescribe or recommend workouts which involve running for varying amounts of time at lactate-threshold velocity. This practice harkens back to the research of Swedish physiologist Bertil Sjodin and his colleagues (3), whi appeared to find that a weekly 20-minute workout at lactate-threshold speed, when carried out over a 14-week period, improved lactate-threshold velocity significantly. Bertil's bunnies were not compared with runners who worked at paces faster than their thresholds, and in fact there was not even a control group in Bertil's inquiry, but the practice of running at threshold caught on, and it is still extremely popular today. In-vogue running books and beloved running magazines recommend training at threshold, and exercise scientist in respected laboratories report that they are regularly contacted by runners and triathletes who would like to know the "best" way to estimate lactate threshold; frequently, these athletes have been instructed by their coaches to carry out a significant amount of training at threshold each week.


      So, let's say that you'd like to be a conventional sort of runner and carry out some at threshold training, with continuous runs at your threshold pace. What is the best way to estimate your threshold?


      You could have your threshold speed measured at an exercise-physiology laboratory, of course. You would end up with an extensive print-out of your blood lactate readings at various running speeds, and you might even enjoy a chat with an exercise physiologist about what the data points really mean. But, the procedure would be expensive and time consuming, and your test would probably be conducted on a treadmill, with no assurance that your lactate profile would be identical to the one obtained while you were running on something like, say, good-old Mother Earth. Also, you would need to perform the test several times over the course of a season, as your fitness changes, and that means having lots of bucks and - hopefully - living not too far from a hospitable exercise physiology laboratory.


      Naturally, you could utilize one of the commercially available, portable, lactate analyzers, which are pretty accurate and have come down in price to reasonable levels. However, you must prick your finger or ear repeatedly to carry out the threshold test, and you must be a little savvy with your blood sampling and handling techniques. WIth all the bloodletting, your mind may not be completely focused on your running (thus giving you a false reading for your threshold speed), and you can easily screw up the bloody part of theprocess. Don't forget, too, that when the bloodbath is over you will still have to "fit the curve" (graph your blood-lactate levels as a function of running speed). Once your graph looks nice, you also must decide in unerring fashion exactly where lactate threshold is to be found on the upward-curving line.


      In contrast with these first two possibilities, Jack Daniels' "VDOT methods" for determining lactate-threshold velocity is a bit easier on your wallet and pain receptors. Described in his book, Daniels' Running Formula, the VDOT method calls for you to enter your performances at a variety of distances into equations and tables developed by Daniels  (4). Your velocity at lactate threshold, along with other important training speeds (including interval pace and marathon tempo, for example), can then be calculated.


      A 3200-meter time trial is also considerably more facile to conduct than a full-blown lactate-threshold exam and has been thought by some to provide a reliable estimate of lactate-threshold velocity. For this test, you only need to do one thing: On a day when you are feeling great and gale-force winds are not whipping across the track, you perform a maximal-effort 3200-meter run. You then calculate your lactate-threshold velocity (LTV) with the following equation:


      LTV (in meters/minute)  = 509.5 - 20.82 X [3200-meter time in minutes]


      Let's say, for example, that you completed your 3200-meter run in 12:15. Changing 12:15 to 12:25 minutes and plugging it into our equation, we have the following:



      LTV = 509.5 - 20.82[12.25]


      LTV = 509.5 - 255.05


      LTV = 254.45  meters  per  minute  (or 1609/254.45 = ~ 6:19 per mile)



      Although this technique appears to be slightly suspect (note in this case how close LTV is to the full blast 3200-meter speed), research has found that it predicts the running speed linked with blood-lactate levels of 4.0 mmol L-1 pretty accurately, and the running speed coinciding with 4.0 mmol L-1 is often considered to be LTV (5).



To learn more about Get Your Lactate-Threshold Speed In 30 Minutes  (the full article can be read by purchasing Vol. 21 Issue 8 of Running Research News) and many more running related topics, simply click-on the Back Issues link, and select the volume and issues number, from the drop-down menu. A subscription to Running Research News is another way to receive valuable information about running. BUY NOW.