What is lactate & why you should test?

What is lactate?

There is a common belief that lactate causes fatigue, contrary to this belief lactate is a useful fuel source for the body at lower intensities and only acts as a marker of fatigue, not causing fatigue itself. It is however the rise in hydrogen ion concentration in the blood which causes the muscles to fatigue due to a lack of available oxygen.

Lactate production increases in a non-linear fashion alongside exercise intensity. It is produced at higher intensities and subsequently utilised as a fuel source by the slow twitch muscle fibres at lower intensity exercise. Higher intensity activity is fuelled by carbohydrates; converted to glucose in glycolysis and lactate is an end product of this!

What does lactate tell us?

Whilst we have established lactate does not cause fatigue, we do know that lactate is a useful marker to determine fatigue and glycolytic activity. An athlete showing prolonged raised blood lactate levels above baseline can be certain to be gradually fatiguing and regardless of fuelling, it is inevitable that exhaustion will eventually be reached.

With lactate being indicative of carbohydrate utilisation, it can be used to determine the given intensities that carbohydrate usage is increased. This can be useful to create a fuelling plan if the desired intensity for an event is known.

So why should you test?

A progressive submaximal lactate threshold test will provide two key data points LT1 (aerobic threshold) and LT2 (anaerobic threshold). This has been deemed the gold standard for testing endurance athletes in exercise physiology literature. This can be used to create a 3-zone model of training zones and can be further broken down into further training zones for specific purposes.

The threshold you gain from a lactate test will be a distinct power number where lactate begins to accumulate rapidly once this threshold is surpassed, rather than a mathematical estimate used in field based power threshold tests!

One way to utilise lactate testing is to track progress over time. For example, you would complete a test pre and post a specific training block and comparing the results will show the impact that that block has had on these key data points. An aerobic training block is likely to have a greater impact on LT1 and a more threshold, VO2max and anaerobic training block is likely to have a greater impact on LT2. It is important to understand the crossover and that most endurance protocols will impact both LT1/LT2 in some way.

Training use:

Assessing the location of LT1 and LT2 on the lactate curve allows coaches and athletes to assess the area of their performance which is a relative limiter or strength, in order to make the next steps in their performance.

Get in touch!

If you’re interested in booking in for a lactate threshold test please contact:

Will Thompson

Instagram: @_peakflowperformance

Email: wtcyclecoaching@gmail.com