Anaerobic metabolism is the umbrella term for, in layman’s terms, how your body burns calories for energy and other body processes. Once you learn a bit more about this process, you can use it to your advantage. Before you start it helps to know that the first thing your body does when you eat is convert the food into glucose.
The second thing to know is that the calories in our food come directly from the glucose, which is simply the sugar. The more sugar there is in our food, the more energy it provides. This glucose provides energy though because it contains ATP. ATP meanwhile stands for ‘Adenosine Triphosphate’ and is the ‘energy currency’ of all life.
ATP is actually made of three phosphate molecules that are bonded together and it’s by breaking these bonds that the body is able to release energy to fuel our movements.
When you eat a whole lot of food, this then enters the stomach and gets digested. At this point, your blood will absorb both the glucose in the food for fuel and the nutrients it can use for various functions throughout your system.
When your blood sugar spikes, this will trigger a few different events. First, it causes the release of insulin, which is a hormone that tells the body to use that sugar in the blood for energy. If you are exercising at this point, then that energy will help you to move around. But if you are stationary, the energy might be stored as fat – converted into triglycerides and added to fat cells.
This process also causes some chemical changes in the brain. Most carbohydrates contain the amino acid tryptophan for instance and this can be used by the brain to make the neurotransmitter serotonin. Serotonin is the ‘feel good hormone’ that puts us in a good mood and it is also linked to appetite.
When you have high serotonin, it also increases your leptin which in turn makes you feel fuller. Eventually serotonin is broken down to create melatonin, which is why we often feel tired after a big meal. When we haven’t eaten for a while, serotonin is low, we get grumpy and this causes us to become ‘hangry’ (we’ve all been there). This also increases ghrelin, the hormone that increases appetite.
Notice how our moods and our neurotransmitters are so closely tied to our biology and our physical states! Often when you think you’re in a good mood or bad mood, it actually comes down to the condition your body is in at that given time! This relationship also works both ways – when you feel sad you’re more likely to crave food which is why we ‘comfort eat’.
This also shows us the important role of insulin and insulin sensitivity. People with type 2 diabetes have a resistance to insulin and that means that their bodies don’t use the glucose in their blood. In turn, this can cause them to feel tired and lethargic and it means that the sugar can end up causing nerve damage and leading to other problems.
Even without diabetes, insulin sensitivity can fluctuate from person to person and our diets and lifestyles can impact on this significantly.
Anaerobic Metabolism is Essentially How We Use Energy
So that’s how the energy ‘input’ works, what about output?
Well essentially, when you start exercising, your body will go through three ‘stages’ in order to get energy form your body.
These stages are:
Anaerobic A-Lactic Energy System
A critical part of anaerobic metabolism is ATP. Also known as ‘ATP-CP’ (ATP Creatine Phosphate), this system uses the ATP that is readily available in the cells and the muscles. This ‘readily available’ ATP is capable of providing a short burst of energy up to 10 minutes, it is very forceful and immediately available.
The role of creatine phosphate is to allow us to recycle used ATP. When you break the bonds that make up ATP, you are left with a ‘two’ and a ‘one’. This gives you an adenosine monophosphate and adenosine diphosphate. If you have enough creatine phosphate, then you can recombine those to make a new ATP for a couple of seconds of extra energy. This is why athletes will supplement with creatine, which can also be found in steak or in some organ meats in higher quantities.
You will rely purely on the ATP-CP energy system when sprinting, when jumping, or when punching. It is also used for powerlifting and anything else that requires max strength for a short duration. As we discussed in other articles these heavy, max-effort workouts answer the question how to lose weight fast for men perfectly.
Anaerobic Lactic Energy System
This part of anaerobic metabolism is also called the ‘fast glycolysis’ energy system and can be used for medium-intensity activity. This energy system is what kicks in when you run out of useable ATP in the muscles and must look elsewhere. Now you start to plunder the blood for glucose and the muscles for glycogen (stored glucose). This must be broken down via several chemical reactions to create more ATP and for every molecule of glucose that gets broken down by pyruvate, you get two molecules of useable ATP.
This form of energy can only last up to two minutes before running out completely. It also has one other limitation, which is that it creates a by-product called ‘lactate’ (which you may know as lactic acid). This is what creates the burning sensation in the muscles that you may associate with prolonged exercise. Now that you know about anaerobic metabolism, its time to move on to the aerobic system.
If you keep going past this point though, the body will need to look elsewhere for energy. Humans actually evolved for aerobic activities and it is widely believed that we used our endurance as our primary tool for tracking prey in the wild.
Essentially, the aerobic system uses oxygen in order to burn fat and carry the energy to the necessary muscles and organs. This incorporates a number of other systems known as the krebs cycle and electron transport cell in order to re-synthesize ATP in the mitochondria; those being the ‘energy centers’ that provide each cell with energy.
Fat is stored as triglyceride in adipose tissue just beneath the skin and within the skeletal muscles (known as intramuscular triglyceride).
The aerobic system is much ‘slower’ than the anaerobic metabolism systems and this makes us weaker during physical exercise. However, it also lasts a lot longer and theoretically can continue until we run completely out of stored fat! This is where the hacking comes in that can boost your metabolism.
However, if you need energy very quickly and you attempt to sprint, then your body will not be able to deliver energy quickly enough to meet that demand using this system and you will revert back to one of the other two anaerobic metabolism systems.
This is an important factor when it comes to the the use of HIIT routines.
One thing to keep in mind here is that the body will burn fat using a pre-determined genetic sequence (as far as we are aware). So some people will exercise and very quickly see their stomach fat fall away as they develop the ideal physique. Other people though will train and find that they lose fat in their breast and muscles and can’t shift the weight on their stomach. Unfortunately, there is no changing this!
Boost Your Metabolism Fast
When we exercise, our body is in a highly ‘catabolic state’ meaning that we are burning fat and breaking down tissue for energy. The heart rate increases and we produce lots of hormones and neurotransmitters that increase our metabolism as well as our focus and energy levels.
To some extent the metabolism is controlled by the thyroid hormones T3 and T4, which control the rate at which cells use energy. This also helps us regulate our temperature – when you increase your metabolism during exercise, your thermogenesis increases and you get hotter as you burn fat and energy for fuel at a faster rate. This is just the same way that a computer gets hotter when you start playing the most graphically-intensive computer games. We then sweat to cool ourselves back down and to regulate our temperature – just like a fan keeps your computer from overheating!
This also causes us to release adrenaline, which is associated with the ‘fight or flight’ system regulated by the sympathetic nervous system. This is what causes our heart rate to increase, blood circulation to accelerate and veins to widen. It also directs more blood to the muscles and the brain and away from other functions like digestion and like the immune system.
When you stop exercising though, your hormone production changes and your body starts to calm down. You’ve just put a great toll on your system and this has broken down a lot of tissue, fatigued your adrenal glands and generally worn you out. Using your muscles has caused the build up of metabolites and lactic acid, while tiny microtears in the muscle fiber have also occurred.
Now it’s time for your system to recover and to heal, ready for the next time you need to expend energy. Thus your system essentially reverses and goes from this highly ‘catabolic’ state and into an ‘anabolic’ state. This is when you release hormones that make you rest and that trigger the rebuilding of muscle and tissue. This process itself actually burns calories though, as your body needs energy to rest and restore your muscles. The most anabolic state your body can be in? That would be sleep! This is when we produce the most growth hormone and it’s when we repair tissue, build muscle and grow as children.
The rest of the time, our body will remain in a state somewhere between this anabolic and catabolic state which is known as ‘homeostasis’. All of us though will have a slightly different base level for most of our hormones.