This article is the Second Part of a Series on Optimizing Run Training
Metabolic Pathways Overview
- Anaerobic ATP-PC (often referred to as phosphagen) system - Short term.
- Aerobic glycolysis (break down of sugar) - Mid Term also called the Lactate System
- Aerobic mitochondrial respiration (cellular production of ATP in the mithochondrion) - Long term.
The second argument against using anaerobic threshold is that it suggests at this point in exercise intensity, metabolism shifts completely from aerobic to anaerobic energy systems. Anaerobic energy systems (glycolysis and the phosphagen system) do not take over the task of ATP regeneration completely, even at higher intensities of exercise, but augment the energy supply provided from mitochondrial respiration.
The heart rate deflection point is only visible in about half of all individuals and commonly over-estimates lactate threshold. Because of these findings, and errors associated with its use, heart rate variability among populations, I do not recommend the heart rate threshold method when designing endurance training programs for clients. In part 3 I will discuss a simpler and possible more accurate way to monitor this which doesn't require constantly looking at a heart rate monitor.