How Knowing Your Lactate Threshold Can Improve Your Training
As an athlete, you no doubt know about lactic acid and maybe you are still blaming it for the muscle soreness you feel after a strenuous workout. And maybe you’ve also heard of lactate and something called lactate threshold. And maybe you are wondering…are lactic acid and lactate the same thing? And what is lactate threshold and is it important for you to know about it?
Lactic Acid vs. Lactate
Although you will see and hear them used interchangeably, lactic acid and lactate are chemically slightly different…by one proton.
In 1780, lactic acid was first isolated by chemist Carl Wilhelm Scheele in samples of sour milk, which resulted in the name. Lactic acid is not only found in sour milk, but also fresh milk, blood and in the cells of a variety of organisms. It is used widely in the food, medical and construction industries. Although chemists might shudder, in the exercise physiology realm, lactate and lactic acid are thought of as virtually the same thing.
When is Lactate Formed in the Body and Why?
When you exercise, you begin to breathe faster in your body’s attempt to transport more oxygen to the muscles that are working the hardest. In general, the body generates most of its energy by using oxygen but in certain circumstances the body requires more energy than the oxygen can provide. In these cases, the body produces oxygen anaerobically—meaning “without oxygen”—from glucose in a process known as glycolosis.
During glycolosis, glucose is broken down into a substance called pyruvate. Normally, pyruvate is carried to an aerobic pathway to continue to be broken down into energy. When oxygen is in short supply however, pyruvate is temporarily broken down into lactate, which permits glucose breakdown to continue to produce energy for the muscles. This process can continue at a relatively high rate for somewhere between one to three minutes and, during this time, lactate is building up to high levels as well.
High lactate levels actually slow the muscles’ capacities to work properly, which seems like the body biting the hand that feeds it, so to speak. In actuality, this slowing of muscles’ work rates is the body’s defense mechanism to protect itself during phases of intense physical exertion.
Once the physical exertion level returns o normal and oxygen becomes readily available, lactate converts back to pyruvate, allowing the body to continue the regular aerobic metabolic process and your body to recover from the intense exertion.
It was a long-held belief that lactic acid build-up was the cause for delayed-onset muscle soreness. And although lactate build-up does cause a burning sensation in muscles during physical exertion, it does not cause muscle soreness afterward.
What Is Lactate Threshold and How Is It Measured?
Lactate threshold is the intensity of exercise at which lactate begins to collect in the blood. Up to a certain exercise intensity level, lactate can be dealt with by other parts of the body and so lactate levels in the blood remain low. At a certain intensity level however, the body can no longer process the excess lactate and it spills over into the blood and begins to accumulate. The point is known as the lactate threshold.
Lactate levels in the blood can be measured at various points during intense exercise by drawing blood samples. Results from blood testing can vary widely with samples drawn from arterial blood being the most accurate and those from veins and capillaries being the least accurate.
What is Lactate Threshold Training and What Can It Do For You?
By finding your lactate threshold, you can target certain training zones and calculate improvements in fitness level. By consistently training at or at least close to your lactate threshold, your body will become better able to clear lactic acid and utilize it to re-energize your muscles. Eventually, lactate threshold training will enable you to delay the point at which lactate spills over into the blood allowing you to run longer and faster before becoming fatigued.
So, you may be wondering if you need to have your blood tested at various points during a run to harness the power of lactate threshold training. Certainly some world-class athletes might want to approach it this way, and although it would be highly accurate, there are other ways to gauge lactate threshold on your own that will be accurate enough to improve your training.
In an article on Competitor.com, author Matt Fitzgerald details three do-it-yourself lactate threshold methods:
This method can be conducted on a track or any smooth surface that will allow you to run fast or alternately, on a treadmill set at a 1% grade. You will need a way to monitor heart rate, elapsed time and distance. Because this method is the equivalent of running a hard race for 30 minutes, choose a day when you are not tapped out from a hard run or workout. After a couple of minutes of easy jogging as a warm-up, begin by tracking time, pace and distance and run for 30 minutes at a pace that is the fastest you can hold for that period of time. At the 10-minute mark, note your heart rate. (Be careful not to start too fast or too slowly to avoid speeding up or slowing down in the latter half of the trial. If you don’t maintain a steady pace, the results will be inaccurate.) When you stop at the 30-minute mark, note your heart rate again. Add your heart rates at 10 minutes and 30 minutes and divide by two. That is your lactate threshold heart rate. Your lactate threshold pace was the average pace during the 30-minute trial, presuming that you didn’t speed up or slow down.
This method involves an LED sensor in a sleeve worn on the calf that noninvasively gauges lactate concentration in the blood and is tracked by an app on a smartphone. The app guides you through a lactate threshold trial, which prompts you to begin running at a slow pace and then increase the pace every few minutes until exhaustion. After the workout, the app collects the data, which then calculates lactate threshold pace and heart rate.
Race time Method
This is the easiest and least painful way to calculate lactate threshold pace—also sometime called tempo pace. Because lactate threshold can be used to predict a runner’s race times fairly accurately, the converse is also true…that race times can be used to calculate lactate threshold. Some online pace calculators such as Jack Daniels’ VDOT Running Calculator (https://runsmartproject.com/calculator/), Tempofit.org’s pace calculator (https://www.tempofit.org/running-resources/calculator/) and McMillan Running’s calculator (https://www.mcmillanrunning.com) all have the ability to calculate lactate threshold pace when you enter a recent race time.
No matter how you calculate it, training at your lactate threshold pace can ratchet your training and racing up a notch. Good luck!
- Jack Daniels' VDOT Running Calculator, web site ,
- Do-It-Yourself Lacate Threshold Testing, web site ,
- Why Does Lactic Acid Build Up in Muscles? And Why Does it Cause Soreness?, web site ,