Bicycle accessories for the discriminating cyclist


Back in the day, many of us were taught lactic acid is only “a caustic waste product”. That’s not what they teach these days. New York Times health writer Gina Kolata’s May, 2006 article, “Lactic Acid Is Not Muscles’ Foe, It’s Fuel” will help bring you up to date. She quotes University of California, Berkeley’s Dr. George Brooks and Auburn University’s Dr. Bruce Gladden, the top minds on the subject in the U.S., if not the world. You’ll see these names again in several of the clinical research citations below.

Lactate, commonly called lactic acid, is turning out to be seriously amazing stuff. Science no longer regards it as a waste product of anaerobic exercise, as was thought for most of the 20th century. Lactate is now recognized as a key carbohydrate muscle fuel source which muscles produce, exchange and consume both at rest and during exercise. And it’s the primary ingredient in SportLegs. What’s alternately termed the Lactate System or Lactic Acid System is now recognized as the primary source of energy for short-term “sprint” activities. Since most competitive sports are nothing more than sequences of sprint activities, lactate remains a focus of current research. For instance, during exercise, it’s recently come to light that your blood may actually transport more lactate than glucose to fuel muscles (20). At rest and during light exercise, your muscles balance lactate production and consumption, producing just as much lactate as they consume (21). But kicking up the pace upsets the balance:

When you start serious exercise, muscles produce more lactate than they consume (1,2,3,4,5), particularly at altitude (2,6), which is why skiers and mountain bike racers suffer more “burn” than most. This continues until the concentration of lactate in your blood rises enough to signal muscles to stop producing excess lactate (7,8,9,10,11,12,13). Until this happens, a domino effect begins which limits your subsequent performance: Lactate accumulates in muscles; limbs “pump up” and feel heavier. The harder you exercise, the more lactate accumulates (14). Lactate accumulated from flow imbalance quickly becomes acidic (14,15) and even less mobile (16), further exacerbating accumulation. This “Lactic Acidosis” is classically associated with reduced Lactate Threshold, reaching the “burn point” at a lower level of exertion. Muscular strength plummets as well (17,18,19).

How taking SportLegs first helps performance: SportLegs uses lactate, your body’s primary high-exertion muscle fuel, to signal muscles not to overproduce lactate before you even begin exercise. Muscles switch from lactate overproduction to net lactate consumption in response to a rise in blood lactate concentration, regardless of whether blood lactate is raised naturally or from exogenous infusion (7,8,9,10,11,12,13). That’s precisely what SportLegs accomplishes. It’s 86.4% lactate. Taken an hour before exercise, SportLegs raises blood lactate, so you experience exercise with less limb “pump” and heaviness, and improved lactate transfer facilitates a noticeably higher Lactate Threshold. Reduced lactate accumulation means less retention of free radicals and other metabolic wastes in muscle tissues, for faster recovery and less next-day soreness.

How taking SportLegs afterward helps recovery: “Because lactate is combusted [metabolized] as an acid (C3H6O3), not an anion (C3H5O3), the combustion of an externally supplied salt of lactic acid, CHO3H5O3- + H+ + 3O2 ¨ 3H2O + 3CO2 effects the removal of the proton taken up during endogenous lactic acid production (Gladden, L. B. and J. W. Yates, J Appl Physiol 54:1254-1260, 1983). A side benefit of alkalizing the plasma by feeding lactate would be to enhance movement (efflux) of lactic acid from active muscles into plasma, a process which is inhibited by low (relative to muscle) blood pH. (Brooks, G. A. and D. A. Roth, Med Sci Sports Exerc 21(2):S35-207, 1989; Roth, D. A. and G. A. Brooks, Med Sci Sports Exerc 21(2):S35-206, 1989). Moreover, maintenance of a more normal blood pH during strenuous exercise would decrease the performer’s perceived level of exertion. The conversion of lactate to glucose in the liver and kidneys also has alkalizing effects by removing two protons for each glucose molecule formed, 2C3H5O3 + 2H+ ¨ C6H12O6. Thus, whether by oxidation or conversion to glucose, clearance of exogenously supplied lactate lowers the body concentration of H+, raising pH.”(22)

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