Lactate Thresholds - Determinants
What are the determinants of the lactate threshold?
The chart below is a model of performance for endurance events
The following are definitions and a brief discussion of each element that feeds into the lactate threshold and thus determines performance:
Aerobic capacity - this is the most important variable determining the lactate threshold in an endurance event but it certainly is not the only one. It is often called VO2 max and it varies considerably over a training season. It is the maximal oxygen transported from the environment to the muscles and used there to create energy for physical activity. It varies depending on the specific activity, since the amount of oxygen that can be transported and utilized for different activities may vary. So an athlete's VO2 max will be different for running versus cycling. It will also vary throughout the training and competitive season. Improving aerobic capacity is the objective of most training for an endurance athlete.
Aerobic power - This is the percentage of aerobic capacity or VO2 max that can be sustained during an event. It is not possible to utilize all of one's aerobic capacity during an event; in reality nearly every athletic event is completed at some fraction of VO2 max. The actual percentage is the aerobic power or the percentage of capacity that can be utilized.
But why cannot an athlete use all his capacity? The anaerobic capacity determines how much of the aerobic capacity can be utilized.
anaerobic capacity - like aerobic capacity it is the ability to generate energy, but through the glycolytic system or the breakdown of glucose. We define it as the maximal or organic potential to produce pyruvate or lactate, which is the output of the anaerobic glycolytic system. This glycolytic system is where lactate originates in the body, and it uses glucose for fuel. The anaerobic system does not produce much energy in an endurance race – most comes from the aerobic system. However, the anaerobic capacity will impede performance if it is either too high OR too low.
The anaerobic system has been ignored by nearly all coaches and exercise physiologists when discussing the training of triathletes. But that is a big mistake. For long endurance events, anaerobic capacity affects performance in two ways besides producing a small amount of energy.
Economy - this is a catch-all for a lot of different things. But essentially the athlete uses energy generated in the muscles to cause contraction of the muscles and this contraction must be directed toward getting the athlete to the finish line as quick as possible. Two athletes can complete a race in the same time but if one of the athletes uses less energy to do so then that athlete is said to have a better economy of motion. There could be several reasons for this:
All these factors come together and produce a physical measure which we call the lactate threshold. And it is this lactate threshold that will determine the performance of the athlete more than any other factor. That is why it is so important and why most endurance training is designed to raise the lactate threshold.
All the modules in the triathlon section are aimed at helping the athlete towards this final goal, raising the lactate threshold.
Other - "Other" is things like psychological factors, hydration, electrolyte replacement, hyperthermia, nutrition, injury etc. Things like wind and current in a distance swimming race, heat and hills in a cycling race or marathon affect things in a major way but this is included under the economy factor, as we are defining economy as everything that affects implementation of aerobic power.
Last update August 7, 2014 All contents © Sports Resource Group, Inc