Lactate Threshold Training

At rest and under steady-state exercise conditions, there is a balance between blood lactate production and removal. The lactate threshold refers to the intensity of exercise at which there is an abrupt increase in blood lactate levels. Lactate threshold training refers to specialized training regimens and workouts focused on improving the lactate threshold.

Purpose

Historically, maximal oxygen uptake has been viewed as the key component to success in prolonged exercise activities. However, more recently it has been recognized that the lactate threshold is the best and most consistent predictor of performance in endurance events. Research studies have repeatedly found high correlations between performance in endurance events such as running, cycling, and race-walking and the maximal steady-state workload at the lactate threshold.

Demographics

Although the exact physiological factors of the lactate threshold are still being resolved, it is thought to involve the following key mechanisms.

Description

KEY TERMS
Acidosis—
Decreased pH.
Anaerobic threshold—
An original concept describing increased lactate production during conditions of low blood flow and oxygen.
Dose-response relationship—
The dose-response relationship refers to the relationship between two variables; where any increase or change in one parameter is associated with a concurrent change in the other parameter.
F.I.T.T. principle—
An acronym that represents exercise frequency, exercise intensity, exercise time, and exercise type.
Gluconeogenesis—
Synthesis of glucose from non-carbohydrate sources.
Glycolysis—
Series of steps that breaks down glucose to pyruvate.
Glycolytic flux—
An increased rate in the transfer of glucose to pyruvate through the reactions of glycolysis.
Heart rate reserve—
The difference between maximal heart rate and resting heart rate.
Hypoxia—
Low levels of blood oxygen. Ischemia—Low levels of blood flow.
Lactate—
A compound manufactured from pyruvate during higher intensity exercise.
Lactate threshold—
Intensity of exercise at which there is an abrupt increase in blood lactate levels.
Maximal oxygen uptake—
The highest rate at which oxygen can be taken up and consumed by the body during intense exercise.
Metabolic pathway—
Chemical reactions causing the formation of ATP and waste products.
Metabolism—
Sum of all energy transformations in the body.
Mitochondrial respiratory—
Reactions within the mitochondrion that ultimately lead to the production of ATP and consumption of oxygen.
Phosphagen system—
Production of energy from coupled reactions of ATP and creatine phosphate.
Pyruvate—
Compound derived from metabolism of carbohydrates.
Rating of perceived exertion—
A subjective rating by an individual of their perception of exercise intensity.
Substrate—
Substance acted upon and changed by an enzyme, such as a foodstuff.

Following adequate build-up in training volume, the next training period to be addressed is steady-state, continuous lactate threshold training. The rating of perceived exertion (RPE) scale may be the most accurate way to determine training intensity during this aspect of training. Research has shown that RPE is strongly related to the blood lactate response to exercise regardless of gender, training status, type of exercise being performed, or training intensity. This is noteworthy, as other methods of monitoring intensity at lactate threshold have been known to have serious flaws in methodology, resulting in under-estimating or over-estimating training intensity. Similar to the time-line increase in training volume, steady-state workout sessions can be increased in duration from a starting point of 10 minutes by 10%–20% per week. Evidence suggests steady-state sessions of 30 minutes in duration are sufficient for optimizing the improvement in lactate threshold during this phase of training. The progression from 10 to 30 minutes steady-state workouts may be accomplished gradually over 6 weeks to 3 months.

Preparation

Knowledge of the metabolic pathways of energy production provides a basis for understanding the importance of lactate threshold training to endurance performance. All energy transformations that occur in the body are referred to as metabolism. Thus, a metabolic pathway is a series of chemical reactions that result in the formation of adenosine triphosphate (ATP) and waste products (such as carbon dioxide). The three energy systems of the body are the phosphagen system, glycolysis (break down of sugar), and mitochondrial respiration (cellular production of ATP in the mithochondrion). The phosphagen system is the simplest energy system of the body with the shortest capacity (up to 15 seconds) to maintain ATP production. During intense exercise, such as in sprinting, the phosphagen system is the most rapid and available source of ATP.

During submaximal endurance exercise, the energy for muscle contraction comes from ATP regenerated almost exclusively through mitochondrial respiration, which initially has the same pathway as glycolysis. It is a misconception to think that the body's energy systems work independently. In fact, the three energy systems work cooperatively to produce ATP. Through glycolysis, blood glucose or muscle glycogen is converted to pyruvate that, once produced, will either enter the mitochondria or be converted to lactate depending on the intensity of exercise. Pyruvate enters the mitochondria at exercise intensity levels below the lactate threshold, while at exercise intensity levels above the lactate threshold the capacity for mitochondrial respiration is exceeded and pyruvate is converted to lactate. It is at this point that high-intensity exercise is compromised, because the glycolytic and phosphagen energy systems that are sustaining the continued muscle contraction above the lactate threshold can produce ATP at a high rate, yet are only capable of doing so for short durations of time. In summary, the energy for exercise activities requires a blend of all the energy systems.

However, the determinants of the involvement of the particular energy system are highly dependent on the intensity of the exercise.

LACTATE IS NOT THE CAUSE OF FATIGUE

The classical explanation for the cause of fatigue, denoted by sensations of pain and the muscle ‘burn’ experienced during intense exercise, is lactic acid build-up. Coaches, athletes, personal trainers, and scientists alike have traditionally linked lactic acidosis with an inability to continue exercise at a given intensity. Although the lactate threshold indicates that conditions within the muscle cell have shifted to a state favorable for the development of acidosis, lactate production itself does not directly contribute to the fatigue experienced at high intensities of exercise. It is the proton accumulation, coinciding with but not caused by lactate production, that results in decreased cellular pH (metabolic acidosis), impairing muscle contraction, and ultimately leading to fatigue. The increased proton accumulation occurs from a few different biochemical reactions during intense physical exercise, most notably in the splitting of ATP at the skeletal muscle for sustained muscle contraction.

Risks

Results

The lactate threshold is dependent largely on training status of the individual. In a nonexercising individual lactate threshold ranges anywhere between 40% and 55% of maximal oxygen uptake. The lactate threshold for individuals who are recreationally endurance-trained is approximately 65% of maximal oxygen uptake. Elite, endurance trained individuals have lactate threshold values upwards of 75%–80% of maximal oxygen uptake; and in some instances even higher. Frank Shorter, winner of the gold medal in the marathon in the 1972 Olympics, reportedly had a lactate threshold that was at an incredible 92% of maximal oxygen uptake.

Resources

BOOKS

Bompa, Tudor O., and G. Gregory Haff. Periodization: Theory and Methodology of Training. Champaign: Human Kinetics, 2009.

Katch, Victor L., William D. McArdle, and Frank I. Katch. Essentials of Exercise Physiology, 5th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins Health, 2016.

Weltman, Arthur. The Blood Lactate Response to Exercise. Champaign: Human Kinetics, 1995.

WEBSITES

“Lactate Threshold.” Lactate.com . May 30, 2016. http://www.lactate.com/lactate_threshold.html (accessed January 20, 2017).

Mackenzie, Brian. “Anaerobic Threshold Testing.”1997. https://www.brianmac.co.uk/hrm3.htm (accessed January 18, 2017).

Robergs, Robert. “Exercise-Induced Metabolic Acidosis: Where do the Protons Come From?” Sportscience 5, no. 2 (September 2001). http://sportsci.org/jour/0102/rar.htm (accessed January 20, 2017).

ORGANIZATIONS

American College of Sports Medicine, 401 W Michigan St., Indianapolis, IN, 46202-3233, (317) 637-9200, Fax: (317) 634-7817, http://www.acsm.org .

American Council on Exercise, 4851 Paramount Dr., San Diego, CA, 92123, (858) 576-6500, (888) 825-3636, Fax: (858) 576-6564, support@acefitness.org, http://www.fitness.gov .

IDEA Health and Fitness Association, 10190 Telesis Ct., San Diego, CA, 92121, (858) 535-8979, (800) 999-4332, Fax: (619) 344-0380, contact@ideafit.com, http://www.ideafit.com .

USA Track & Field, 132 E Washington St., Ste. 800, Indianapolis, IN, 46204, (317) 261-0500, Fax: (317) 261-0481, http://www.usatf.org .

Lance C. Dalleck, BA, MS, PhD

  This information is not a tool for self-diagnosis or a substitute for professional care.