Revel Sports - Lactate at the Track

THE RUNNING RESEARCH NEWS WEEKLY TRAINING UPDATE

ISSUE # 26 OCTOBER 30, 2004

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Hi Everyone,

I have never been a big fan of bloodletting on the track.

Please let me explain what I mean. Most runners, cyclists, swimmers, Triathletes, and coaches have accepted the idea that lactate-threshold velocity (the speed above which lactate begins to pile up in the blood) is an important predictor of performance capability. With certain qualifications, that is a wise acceptance.

As a result of this affirmation, many coaches and athletes actually measure blood-lactate levels during training. One relatively common practice is to utilize a "graded" workout in which intervals are conducted at increasingly fast speeds in order to identify the lactate-threshold velocity, or LTV. The blood-lactate concentration associated with each speed is plotted graphically, and the "turn point" - the velocity at which lactate levels make a dramatic jump - is reckoned.

The estimated LTV is then commonly used in two ways: (1) It can be regarded as a "benchmark" LTV which should improve if training is going well. The graded test can be repeated every four to six weeks or so, for example, and if the new LTV is higher than the old, the athlete can breathe a sigh of relief and believe that he/she is making progress. (2) In addition, some athletes carry out 20- to 30-minute, continuous, "tempo" efforts at the estimated LTV in hopes of fattening LTV further.

As mentioned, underlying all of this is the belief that LTV is a great marker of fitness - and that competitive ability expands as LTV increases. However, recent research carried out in Great Britain reveals that this is not always the case (1). In fact, this important study links decreases in LTV with better performances - and increases in LTV with shoddier efforts!

In the British investigation, competitive swimmers (both males and females) who significantly improved their LTVs from .67 meters per second to .70 meters per second experienced a significant slow-down in 400-yard swimming performance from 300 to 308 seconds. In contrast, experienced swimmers whose LTVs suffered, dropping from .69 to .67 meters per second, actually upgraded their 400-yard times from 304 to a nifty 298 seconds!

What was going on? As it turned out, the poor link between LTV and performance was directly related to the athletes' diets. When the swimmers stepped up their carbohydrate consumption, they performed at a higher level because their muscles were better-stocked with glycogen. However, they produced more lactate at any specific speed (lactate is a direct product of carbohydrate metabolism, upon which the swimmers' muscles relied more heavily when carb intakes swelled), and thus LTV went south. When the swimmers' diets were carbohydrate-poor, they swam more slowly because their muscles were relatively glycogen-depleted, and yet LTV increased because it was hard for the muscles to cough up much lactate (the sinews had shifted over to a heavier reliance on fat, the metabolism of which produces very little lactate).

Thus, athletes and coaches who measure lactate levels and estimate LTVs from those blood readings are in a tough spot! Do those lactate concentrations really reflect fitness - or diet? Unless such athletes/coaches absolutely standardize diet and ultimately muscle-glycogen level going into each test, they will never know. And - such standardization is not the easiest thing in the world to pull off.

Thus - my avoidance of track bloodletting is not based on phlebotophobia but rather on difficulties associated with lactate measurement (and the ultimate use of such measurements, too). Of course, you may be thinking, "If I can't measure LTV accurately, how can I train at LTV in order to improve it?"

My simple answer would be that you do not need to train precisely at LTV in order to upgrade it - and that in fact there are probably many intensities (above LTV) which are much-more-productive LTV enhancers. Research carried out by Veronique Billat, for example, has shown that training at vVO2max (the minimal speed which produces the maximal rate of oxygen consumption) is a potent LTV booster. Fortunately, the vVO2max test - running all-out on the track for six minutes - is a resilient exam with very manageable variation which instantly provides a great training speed (the average velocity established during the test, which is the estimate of vVO2max). Of course, it is pleasing that such testing does not require several stabs of the finger or ear lobe (and that the test itself is over in just six minutes).

The bottom line? During your training, you don't need to measure your blood lactate or estimate your LTV. If you are carrying out high-quality training, with judiciously planned efforts at vVO2max and at other eminent speeds (at 10-K pace and faster), and you are conducting hill training and running-specific strength training in a systematic way, you can be confident that you are steadily pushing your LTV in the right direction.

One final note: Many of you may have been wondering why this "weekly" update has not appeared in your inbox for several weeks. I am sorry to report to you that my mother passed away on August 28, and I have essentially been out of action since then. Going forward, however, expect to see your update in your mailbox each Saturday morning. I thank you all very much for your patience and support.

Very kindest regards,



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