Hard Workouts to Improve Lactic-Acid Threshold

by Karl Gruber
Almost every runner I know — including myself — experiences a fair amount of muscle soreness after racing 26.2 miles. 

The buildup of lactic acid in our muscles that results from a long, hard run is often considered the main source of muscle soreness. Lactic acid is the byproduct of burning the fuel in your muscle fibers (glycogen) without the presence of oxygen. However, it has since been shown that lactic acid actually gets flushed out of your muscles rather quickly. The real source of muscle soreness comes from micro tears in your muscle fibers from the hard effort. Lactic acid may not be the main reason for post-marathon soreness, but it still is a contributor to soreness. 

In an article entitled How to Push Past Your Lactic Acid Limits, two-time Olympic Marathon competitor Ed Eyestone noted that with the correct training, you can delay the onset of lactic acid accumulation and improve your body's capacity to use it for fuel. This is an eye-opening statement, because the notion that lactic acid build-up is the main source of post-hard workout muscle soreness is a long-held belief. However, Eyestone states: 

“In a 2006 study at the University of Western Australia, researchers found that athletes who worked out at 120 to 140 percent of lactate threshold three days a week for five weeks improved their ability to buffer hydrogen ions by about 25 percent. In athletes who worked at a lower intensity-95 percent of lactate threshold-buffer capacity stayed the same. By running beyond your lactic-acid threshold…you train your body to more efficiently process it into a fuel, and at the same time, improve your capacity to buffer those hydrogen ions. All of which will help you run faster, longer.”

After many years of thinking lactic acid causes muscle soreness, this idea of running harder workouts seems counter-intuitive — but the science is there. Eyestone even has some recommended fast and hard run workouts that offer big rewards. 

Interval Recovery
6 x 300 2 minutes
4 x 400 4 minutes
8 x 200 90 second

According to Eyestone, "Try one of these workouts every two or three weeks instead of an interval session. Run the repeats at your 800-meter pace, or at about 90 percent of all-out effort.”

If you recently raced a half or full marathon and would like to improve your lactate threshold, you now know there is reason to do a short race soon. A perfect example of a short race coming up soon is the Fleet Feet Liberty Mile on Friday, August 9, 2019. 

Consistently recognized as one of the The 35 Most Iconic American Races by Runner’s World, the Fleet Feet Liberty Mile is Pittsburgh’s favorite one-mile timed street race. This “night at the races” brings friends and families together to celebrate fitness through one-mile races for recreational, competitive and professional runners. Launched in 2012, the race is consistently praised for its entertaining vibe, inclusivity and gorgeous views. 

From average joe’s to pros, thousands of runners of all ages and abilities are expected to compete in eight different race heats during Pittsburgh’s only nighttime downtown road race. To register or for more information, visit

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