In “The energy systems” the different energy systems of the human body were explained. In that article the phosphagen, aerobic and anaerobic systems were covered and briefly explained. Everybody knows that acidification and lactate production due to the anaerobic system are not desirable during your exercise workout. So it won’t be a surprise that the Lactate Threshold (LT) is such an important parameter in your training plan! 

As discussed previously (The energy systems), the anaerobic contribution to energy production isn’t necessarily problematic. The body is capable of dealing with some of the waste products, as long as it’s produced at a certain rate.  The waste-product production will be more problematic when the production rate surpasses the processing rate of the waste products. At this point, lactate and hydrogen ions will build-up in the blood and within the muscles, resulting in the rise of blood-concentrations, a restricted muscle contraction and deteriorating performance. This tipping point is called the Lactate Threshold. When the contribution of the anaerobic system increases during more intense exercises or bursts, this point will be reached quickly.

 

The Lactate Threshold

Whereas the cardiovascular fitness sets the upper limit for the aerobic system (reflected by VO2max), it’s the metabolic fitness (reflected by the lactate threshold) that determines the fraction or percentage of VO2max that can be utilized for a certain amount of time without acidification. A higher LT (as percentage of VO2max) has two advantages:

  • An athlete is able to sustain an effort at a certain intensity for a prolonged period.
  • An athlete is able to sustain an effort for a certain duration at a higher intensity.

Normally, the threshold is approximately between 40-60% of the VO2max. The faster your body can process waste products, the higher your Lactate Threshold and the faster you will recover from hard efforts. This makes the LT the “single most important physiological determinant of performance in events ranging from as short as a 3km pursuit to as long as a 3-week stage race”, according to Dr. Coggan PhD, a well-respected exercise physiologist. LT is an important predictor of the endurance performance ability of a cyclist, or for any endurance athlete whatsoever, and therefore provides a strong physiological basis for your training program.

 

 

Definitions & Synonymous

Lactate Threshold is a threshold that goes by a lot of terms. In addition, there are some other terms that may be related to the LT but are defined slightly different. What’s the difference between them?

  • Officially, the Lactate Threshold, is the threshold that blood lactate levels start to rise (exponentially). This point can be determined by measuring blood lactate levels.
  • OBLA (Onset of Blood Lactate Accumulation) is often defined as a blood lactate level of 4 mmol/L. From this point on, it is hard to exercise without reducing the intensity. For a clear and extending description, I would like to refer you to https://www.trackcyclingacademy.com/blog/understanding-lactate-for-track-cyclists
  • The (Ventilatory) Anaerobic Threshold (VAT) is the Anaerobic Threshold determined with gas-exchange analysis. By measuring the oxygen uptake and carbon dioxide release during an exercise test, one is able to determine the “Lactate Threshold” pretty accurately. When the Lactate Threshold is determined this way, it’s called the Ventilatory Anaerobic Threshold, or VAT.
  • The functional Threshold Power is “the highest power output one can maintain in a quasi-steady state without fatiguing.” This point coincidences with the LT or Anaerobic Threshold (VAT). This way, the LT can be linked to the power output, taking into account the cycling efficiency. Therefore, the FTP is very practical to determine your training zones. In addition, the same thing can be done when using heart rate, instead of power, as a zone-limiter (FTHR).

Next: VO2max

 

References:

  • Friel J. The Cyclist’s Training Bible. 5 ed: VeloPress; 2018.
  • Allen H, Coggan A, McGRagor S. Training + Racing With a Power Meter. 3 ed. Boulder, Colorado: VeloPress; 2019.

Want to know your own VO2max or Lactate Threshold? Or do you need help with your training? Let us know via cycling@science2move.nl or have a look at https://de-vitaliteitspraktijk.nl/inspanningstesten/conditietest/.