Posted: April 9, 2005

Science of Sport: Lactic Acid Reduces Fatigue

The Running Research News Weekly Training Update - Issue # 42, April 7, 2005

Hi Everyone,

In 1929, the revered exercise physiologist A. V. Hill isolated frog muscle cells and forced them to fatigue by stimulating them electrically. He noticed that as the frog fibers became increasingly tired, they tended to accumulate large quantities of lactic acid (1). Adroitly, Hill transferred the froggy sinews to a saline solution which allowed the lactic acid to dissipate, and with this dissipation came a renewed vigor on the part of the cells.

Although many explanations were possible for these interesting events, Hill settled on the idea that the piling up of intracellular lactic acid was a principal cause of muscle fatigue. His hypothesis was "verified" by later work which seemed to suggest that intracellular "acidosis" caused by a build-up of lactic acid could thwart force production by the key proteins inside muscle cells (2).

Of course, when A & B occur together, and the removal of B is associated with the reversal of A, it is tempting to think that B causes A. But just as high rates of under-age drinking are not really linked with improved SAT scores, lactic acid does not truly promote tiredness in muscles. The problem is that when one focuses strictly on A & B, then C, D, and E are ignored. The occurrence of two things together does not prove causation, especially in biological systems - where an incredible number of variables are interacting simultaneously.

Later research, in fact, showed that the lactic-acid-fatigue link was very tenuous. One study, for example, found that individuals whose muscle cells are incapable of producing lactic acid actually experience fatigue more quickly, compared with persons whose muscles spew out large quantities of lactic acid (3).

Another investigation found that the acidosis effect, by which an acetous intracellular milieu puts the stopper on muscular force production, was present at low temperatures - but was barely noticeable at typical body temperatures (4). Other work carried out with single muscle cells has shown that acidic conditions have no effect at all on fatigue (5)!

And now, the capper: A very recent study causes us to reject Hill's hypothesis completely. In very new work, researchers have shown that in fact the addition of lactic acid has beneficial effects on the force production of very tired muscles (6). You heard it here first!

In this up-to-date research, investigators revealed that increased levels of lactic acid influence the activity of chloride-ion "channels" in muscle cells; this change in activity sustains force production by muscles, instead of limiting it!

What does all of this have to do with you, the endurance runner (or cyclist, swimmer, skier, rower, or canoeist)? It means once again that developing a huge capacity to bring lactic acid in to your muscle cells will have a major impact on your performances.

Believe it or not, that capacity to bring lactic acid home is not fostered by 100-mile weeks, or by the traditional "development of aerobic capacity." It is in fact enhanced by sizzling, red-hot workouts which flood the blood with lactic acid, a flooding which causes the muscle cells to perk up and say "Hey - we need to get better at clearing this stuff out of here!"

Your muscle cells, you see, have receptors for lactic acid which grab the little lactates as they swim feverishly in the blood; these receptors can pull the fine lactate fellows inward. If you run 100 miles per week at moderate intensities, your receptor fauna is impoverished, because your muscles don't like to do anything they don't need to do. If there's not much lactic acid in the blood, they see no need to fire up receptor production.

On the other hand, if you pencil Lactate-Stacker Sessions into your program with regularity, your muscles will have no choice but to drum up lactate-receptor synthesis, a production which will reduce your fatigue during fast running and lead to better performances in your races.

The Lactate-Stacker Session is one of the easiest workouts to put together: After a good warm-up, all you need to do is blast along at close-to-max speed for one-minute work intervals, with two-minute (jog) recoveries. Start with just six work intervals for your first Lactate-Stacker session, and progress to more reps over time.

Research carried out by the godfather of modern exercise physiology, Per-Olof Astrand of Sweden, has shown that just eight one-minute intervals (with two-minute recoveries) produces a blood-lactate concentration of almost 16 mMoles/liter in the typical athlete, an incredible outpouring which will have your muscle cells stacking up dense growths of receptors on your leg-muscle membranes (7). As your muscle membranes become tangled forests of lactate receptors, your performances will improve at all distances from 800 meters up to 800 miles. Use the Lactate-Stacker session often, and have fun with it (it's nice to know that you can perform this session anywhere you like to run).

References

 
(1) Proceedings of the Royal Society of London, Series B, Volume 105, p. 313, 1929
(2) Journal of Physiology (London), Vol. 276, p. 233, 1978
(3) Journal of Physiology (London), Vol. 418, p. 311, 1989
(4) Journal of Physiology (London), Vol. 486, p. 689, 1995
(5) Journal of Applied Physiology, Vol. 85, p. 478, 1998
(6) Science, Vol. 305, p. 1144, 2004
(7) Acta Physiologica Scandinavica, Vol. 48, p. 454, 1960

Cutting-Edge Running Camps

RRN's business office has authorized me to tell you that a special promotion is now in effect for our summer running camps at Pepperdine University in Malibu, California (the dates for which are June 21-26, 2005 and also July 19-24, 2005). The cost of this camp is ordinarily $995.

However, if you sign up and pay for the camp by April 25, you will receive a 10-percent discount, meaning that you will pay only $895.

And - as part of an even better deal - if you sign up and pay for the camp by April 25 along with another person, your cost per camper will drop to an incredible $800 each ($1600 for the two of you).

You have my personal guarantee that you will love this camp. It is the only running camp in the world which teaches running-specific strength training. It is the only running camp which starts each morning with a beautiful run on the Backbone Trail in the Santa Monica Mountains (please see photo at left). It is the only running get-together which is both highly educational and also incredibly fun. When you attend, you will benefit from the classroom sessions, and you will be thrilled by the workouts at Zuma Beach and Mugu Point. And - you will be happy after our "nights out on the town" in Santa Monica and Hollywood.

These reduced prices are only in effect until April 25; after that, the business office tells me that we must return to our usual $995 humdrum.

To learn more about the camp and download our camp brochure, please go to: www.runningresearchnews.com or else call me personally at 517-712-3578. I hope that I have the opportunity to work with you individually in California this summer.

With very kindest regards,

Owen Anderson