Posted on August 11, 2015 by Jenny Cromack

Fat loss can be achieved if you know how your body uses energy and how to exploit it! This is were intervals come in! Many cardio machines in the gym will tell you to work at lower heart rate’s in order to burn fat, but as we all know, the current focus is on High Intensity Interval Training (HIIT) which uses much higher heart rate training zones to turn your body into a fat burning furnace, compared to the old-fashioned method of long, slow duration, low heart rate training zones.
This blog looks at energy systems and fat loss, and how you can create your body to become a lean, mean fat burning machine.
The three pathways that your body uses to created ATP (The stuff we use for energy!) are

1) ATP-CP System (The Explosive Force)

Examples:

Power Clean
Snatch
40 yard Sprint
Vertical Jump

What it burns….

The ATP-CP system burns creatine that is stored in your muscles and turns this it into ATP

How it works….

If you need to lift a heavy box off the ground, perform a 1 rep max dead lift or sprint for a bus then this is when the ATP-CP system kicks in! In effect it provides quick, short term energy. However, it is quickly exhausted due to limited amounts of creatine and ATP that can be stored in your muscles.

This type of training makes you fast and feel powerful and is used during heavy strength training and short sprints.

How good is this for fat loss?

The ATP-CP system is responsible for burning creatine not fat or carbohydrates. However, the benefit of this energy system is it makes you stronger so with a perfectly tuned ATP-CP system you will increase your work capacity (ie you will be able to work harder and for longer) and make training for fat loss “feel” easier.
2) Anaerobic “Lactic Acid” Glycolytic System

Examples:

Strength Training ,

Hypertrophy,

High intensity interval training,

Sprinting (200-600m)

Combat sports such as boxing and wrestling

What it burns…

Carbohydrates are metabolised from blood sugar or muscle glycogen which produces 2 molecules of ATP. The by-product pyruvate is then formed and this can have 2 reactions.
When you train at a high intensity that results in a lack of oxygen, pyruvate is converted into lactate that results in build up of metabolic waste product. This is basically an increase in hydrogen ions and causes the muscle PH level to increase although this isn’t dangerous it cause some pain and results in a decrease in strength capacity and your exercise intensity decreases

However if you are training at a moderate intensity and you are able to sustain enough oxgen to the muscles, pyruvate is turned into acetyl coenzyme A which is used to make even more ATP so exercise intensity is sustained this is part of the aerobic system.

How it works

If you wanting to perform a number of pull ups for time or you’re running 400m this energy system is ideal as once the ATP-PC system is used up the glycolytic system comes into play and allows you to sustain intensity for another 60-110 seconds! This training system saves time and produces a metabolic disturbance, burning large amounts of calories during and after your workout.

How good is this for fat loss?

This energy is great as it allows you to work at those short bursts you need for HIIT and also results in a greater calorie burn post workout.

3) The Oxidative Aerobic System

Examples

Long duration intervals,

 

Ensurance activies such as Cycling, Jogging, Hiking, Walking , etc
What it burns
This system burns both carbohydrates and fat.

When the intensity is higher such as intervals 0f 2-5 minutes the aerobic glycolytic
system takes over. Pyruvate is turned into acetyl coenzyme A and is used to make larger amounts of ATP. From one glucose module 36 ATP are created compared with only 2 being made during the anaerobic glycolysis.

This is your slow burning energy source which is reliable and sustainable however, despite what those cardio machines in the gym which tell you to work at 65% of your Max HR will tell you, it isn’t the best method for fat loss for 2 reasons:

Firstly, steady state training makes the body as efficient as possible so that you use the least amount of oxygen and energy to perform the greatest amount of work. It is very metabolically efficient which is not the goal if you are looking to drop body fat.

Secondly, low intensity aerobic training such as walking leads to the loss of lean muscle mass over time and your resting metabolic rate goes down and you burn fewer calories. however training long interval with short rest periods that don’t allow you to fully recover can result in a significant metabolic disturbance.