Once exercise intensity goes beyond a certain level the body starts to produce metabolites which cause us to inevitably slow down. This occurs at two distinct points
Firstly, when you transition from steady to moderate intensity, known as; the lactate Threshold which is the point where you start to accumulate lactate above resting values and the body starts utilise more carbohydrate for fuel.
The second distinct point is when you transition from moderate to hard intensity, most commonly known as the Anaerobic threshold (other common terms do exist) and is the maximum intensity before lactate is being produced quicker than it can be cleared by the muscles and is the most important for race prediction and assessing training adaptation.
It is extremely important for any level of athlete to be aware of these distinct points because it will inform them of the maximum speed/power they can sustain for a given distance. It will also inform them of the best options for fuelling strategies to avoid the dreaded ‘hitting the wall’. Probably the most important factor is it allows athletes to accurately set their training zones to avoid either under or over training and to manage the ratio of workload for a given week/month.