Find out more about lactate and how, contrary to it’s popular reputation, this incredible molecule plays many important roles from being used as a preferential fuel source, actually minimise acidity in the tissues and even acts as a ‘signalling hormone’ to drive beneficial adaptations to training.

In this 3 part mini-series discover:

Part 1: The Blood Lactate Story

  • How lactate is produced
  • How the body uses lactate
  • How lactate can minimise acidity in your tissues
  • How lactate helps to preserve other fuel stores
  • How lactate may actually be the preferred source of fuel for the heart during exercise
  • How lactate may act as a ‘shuttle’ to transfer fuel between tissues
  • How lactate acts as a signalling molecule

Part 2: How Can Understanding Blood Lactate Improve Performance?

 

Part 3: Polarised Training

The Blood Lactate Story

Lactate is the ‘base’ of lactic acid. In the human body, most lactic acid is present in the form of lactate. The popular belief used to be that lactate was produced in muscles due to a shortfall in oxygen supply as exercise intensity increased. It also gave rise to the notion of the ‘lactic acid burn’ and that lactic acid was responsible for fatigue during high-intensity exercise.

However, research, such as that conducted by Spurway, 1992), has revealed that lactate is formed and used continuously, even when muscles are working in a fully aerobic state.

During vigorous exercise, there is an increase in the acidity in the blood and tissues. However, lactate makes a very small contribution to this (Robergs et al., 2004). When you’re exercising hard, lots of ATP (the ‘energy currency of life’) is broken down to release energy for muscle contraction. Each time an ATP molecule is broken down, one hydrogen ion is released. Lots of positively charged hydrogen ions in a solution reduces pH. Consequently, it’s the accumulation of hydrogen ions which contribute to the acidic environment in the blood and tissue which may be associated with ‘the burn’.

Additionally, whilst commentators love to talk about how a riders muscles are ‘tying up’ in the final kilometres of a breakaway as the ‘lactic acid’ builds up, in fact, neither lactate or lactic acid are likely to be a cause of fatigue. The human body is incredibly complex and it’s more likely that the limiters to performance are a result of many factors which may work independently or together (Joyner & Coyle, 2008)

How Is Lactate Produced? 

As the intensity of exercise increases, our body requires more energy more quickly, so energy metabolism shifts to begin to favour using more carbohydrate and less fat. Carbohydrate, in the form of glucose, is broken down in a chemical reaction called ‘glycolysis’. One of the end-products of this reaction is a molecule called ‘pyruvate’ which begins to accumulate along with the dreaded hydrogen ions! Pyruvate absorbs hydrogen ions in a ‘reduction’ reaction, which forms lactate.

I’ve Heard That Lactate Can Actually Reduce Acidity. Is This True?

So, the idea that ‘lactic acid’ is in some way detrimental to recovery is a myth. Lactate actually acts as a buffer – mopping up hydrogen ions to reduce the acidity in an attempt to maintain blood and tissue pH. However, the speed of the ‘mopping up’ process has a limit. When this limit is reached, hydrogen ions accumulate, pH begins to drop and we feel the burn! If our muscles did not produce lactate, fatigue would occur much more quickly.

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How Does The Body Use Lactate?

The body uses lactate in a number of ways:

1. Lactate minimises acidity in the blood and tissues

As described above, lactate is the end result of pyruvate’s reaction with hydrogen ions, which reduces acidity and is associated with a delay in fatigue.

2. Lactate helps to preserve other fuel stores

When blood lactate concentrations are elevated, the body responds by down-regulating the use of glucose and fat, so lactate could be seen as preserving precious fuel stores. Also, the body is able to generate glucose from non-carbohydrate sources through a metabolic pathway called ‘Gluconeogenesis’. Lactate is transported back to the liver, enters a chemical process called the ‘Cori cycle’ and is converted into pyruvate which is then used to generate glucose.

3. Lactate is a source of energy for the muscles, heart and brain.

Muscles can extract lactate from the blood and oxidise it directly, using it as a fuel source to liberate energy for contraction (Van Hall, 2000). In some cases, the body actually prefers to use lactate as a fuel. Some research has illustrated that, during moderate intensity exercise, lactate from the working muscles may be the primary fuel source for the heart. Evidence for this comes from the finding that MCT shuttle proteins in the heart – proteins which move lactate from the blood to tissues where they can used – increase in proportion to physical exertion. (Gertz, 1988, Bergersen, 2007)

4. Lactate acts as a ‘shuttle’ to transfer fuel between tissues (Brooks, 2009).

Research suggests that lactate can move both within and between cells. During heavy exercise, where high rates of glycolysis and glycogenolysis (breakdown of glucose and glycogen) result in the accumulation of increasing amounts of lactate in working muscles, lactate can be ‘shuttled’ from this site to other skeletal muscles as well as the heart, brain and liver where is can be used directly as a fuel source or converted back into glucose.

5) Lactate is an important ‘signalling molecule’.

Lactate may play the role of a signalling hormone, with a range of possible consequences. These include up regulating the expression of genes associated with the use of lactate as a fuel (Hashimoto, 2008) and even stimulating an increase in formation of new mitochondria (Brooks, 2009): an important adaptation in endurance performance. It has also been suggested that lactate can influence lipolysis through it’s role as a signaller, regulating the use of fat as a fuel.

Find out more in Part 2 where you can discover:

10 Tips To Improve Cycling Performance