Updated: Oct 28, 2020
1. Avoid lactate accumulation 2. Lower carbohydrate intake 3. Increase VO2max
1. AVOID HIGH INTENSITY EFFORTS DURING TRAINING IN THE FATMAX ZONE.
Lets say your athlete is performing an intense interval training. During the high intensity effort, lactate will accumulate. In the resting phase, their intensity may be at the level where lots of fat would usually be combusted. However, in the recovery phase between or after high intensity intervals, fat combustion is low. Instead, the preferred fuel for muscles in this period is the accumulated lactate.
Intuitively, you know this already. You would not prescribe high intensity interval training and ask your athlete to rest completely and not move in between efforts. The low intensity phases are needed to combust lactate and recover faster.
The same is true during training intended for “fat burning”. Any time lactate is accumulating during the exercise, fat will be pushed out of the aerobic metabolism. Until muscular lactate levels decrease again, fat combustion will stay lower.
All of this means that it is of utmost importance to avoid short, high intensity bouts which cause high lactate levels during training which is meant to be in the FatMax zone.
2. TRAINING IN A LOW CARBOHYDRATE STATE CAN ELEVATE FAT COMBUSTION.
Low carbohydrate diets, and training in low carbohydrate state, have become more and more popular in endurance sports. This idea is based on findings that a state of low carbohydrate availability can increase adaptation to training in terms of mitochondrial biogenesis.
A lowered carbohydrate intake due to an altered diet can decrease the capacity of carbohydrate metabolism. In doing so, fat combustion will be elevated. The result of this is not just an immediate elevation in the percentage of fat combustion, but also an increase in the capacity of the enzymes involved in fat combustion. This can lead to a prolonging of the higher capacity to combust fat. Bear in mind that after your athlete’s diet is back to a higher carbohydrate content, the effect previously described can easily be reversed. The activity of enzymes involved in the carbohydrate metabolism will go back to a normal state.
During a period of lowered carbohydrate intake, it is crucial to minimise high intensity workouts in which carbohydrate combustion is high. This is because, during high such efforts, the body needs to use carbohydrates as fuel.
3. A HIGHER VO2max = BETTER AEROBIC METABOLISM = IMPROVED CAPACITY TO BURN FAT.
A higher VO2max will lead to better fat combustion in your athlete. This is because it creates more mitochondria, improved blood flow due to higher capillary density, and a shift from high glycolytic muscle fibre types to “endurance” types (slow twitch fibres). All of this means a better aerobic metabolism, which then pushes back the involvement of the glycolytic (anaerobic) metabolism.
This results in an improved ability to burn fat. As combusting fat requires more oxygen for the same energy spend compared to combusting carbohydrates, an increase in VO2max will always result in an improved capacity for burning fat. This is true whether accomplished with many hours of low intensity training, or with very hard interval workouts.