ENERGY SYSTEMS DEVELOPMENT
PART 1
To be fit - "of a suitable quality, standard, or type to meet the required purpose" . So, before we can think about getting fitter, we must first define the required purpose effectively.
As a strength and conditioning coach & sport scientist, I'm well aware that people perceive my main role within a sports team or with a client is to improve 'fitness'. While this is true, the term fitness itself means so much more. Very rarely do people specify which part of fitness they want to improve or how they are going to do it. Getting stronger, faster, leaner, more powerful could also classify as getting fitter. For the most part though, and it's going to make up the majority of this article, we'll be talking about the commonly thought about 'fit'. Being able to run further, being able to run faster for longer, being able to do something for longer before being tired, also known as 'work capacity'. What is it, how do we define it properly but most importantly, how can we train it properly.
As a strength and conditioning coach & sport scientist, I'm well aware that people perceive my main role within a sports team or with a client is to improve 'fitness'. While this is true, the term fitness itself means so much more. Very rarely do people specify which part of fitness they want to improve or how they are going to do it. Getting stronger, faster, leaner, more powerful could also classify as getting fitter. For the most part though, and it's going to make up the majority of this article, we'll be talking about the commonly thought about 'fit'. Being able to run further, being able to run faster for longer, being able to do something for longer before being tired, also known as 'work capacity'. What is it, how do we define it properly but most importantly, how can we train it properly.
Energy systems development can seem quite complicated but if you break it down into all it's parts it becomes quite simple. Movement occurs as long as the rate of ATP production matches the demand. I've written a smaller article on ATP and what it is, you should most definitely go and read it. As the intensity of exercise increases, the demand for ATP increases also. When our energy system is no longer able to provide the necessary ATP to maintain a specific exercise intensity/duration, we slow down, or we stop. There are three main energy systems:
- The ATP-PCr = ATP-Phosphocreatine system. This is for extremely high intensity maximal effort activities and only last about 6 seconds.
- Glycolytic = This utilises glycogen or glucose for the production of energy. It happens in the absence of oxygen, thus by-products build up as a result and this leads to fatigue and the cessation of exercise intensity.
- Oxidative = A multi-step process requiring oxygen. Usually occurs during longer duration activities and is the slowest system at providing ATP to the working muscles.
Our energy systems don't have an on-off switch for certain activities, it works on a continuum. The higher intensity the activity the more we'll utilise the ATP-PCr system. As the duration increases our ability to maintain that intensity will drop gradually and we start to use the glycolytic system. Eventually the fatiguing by-products build up so much that we can longer maintain intensity and it drops again. This leads us to using the oxidative system - usually used during longer duration activities like distance running. This example is based on the assumption that one is doing a sustained effort activity, but we know sport isn't like that.
These 3 energy systems can be diverged even further. When it comes to developing efficient energy systems that supply us with the energy that we need at exactly the point that matters, there's a lot more to think of. The variables that we manipulate feed directly into what energy system we are aiming to develop and the adaptations that we get from it. It's why using suicides or conditioning drills is not conducive to trying to develop maximal sprint speed. Maximal sprint speed {Zone 1} is characterised by maximal efforts for ~6 seconds with a full recovery (sometimes up to 5 minutes) while traditional conditioning drills {Zone 2} are usually sustained efforts for 30 seconds with a 30 second break. The table below will give a little bit more clarification on this.
Sport can be characterised by repeated maximal or near maximal efforts interspersed with incomplete recovery periods {Zones 1 & 2}. As a task for yourself, think about your own sport and think about each passage of play? How long does it last? How much time is in between each play? What is the rest like? Is it active rest or is it passive? How intense are the efforts? Thinking about these will allow you to think deeper about the contribution of each energy system to your sport and which one you need to maximise the most.
But, here's the kicker; if aerobic capabilities are deficient in any given athlete, it can lead to a premature activation of the lactate energy system which will decrease speed and acceleration abilities. Let's think about this for a second.
I'm going to take each energy system and talk about it on it's own in detail soon but for now, let's consider this. A large proportion of sports is spent at lower intensities. The ball is out of play, or your team are attacking with the ball and you are a defender. There's a time out. Half time. In most sports, there are a significant number of breaks in play. During these breaks, what energy system do you think is working the most? That's right, the oxidative system. If you can improve your bodies ability to utilise the energy systems that require oxygen, during these breaks in play you are going to be better able to remove those waste by-products from your body and produce ATP more efficiently. All of this makes you a better athlete because you can sprint faster and for longer and deeper into games before fatigue starts to kick in. In any sport, fatigue is inevitable, it's about leveraging yourself into a position to delay the onset of fatigue for as long as possible.
Doing this requires you to optimise your training in each zone and identifying where your weaknesses lie.
Doing this requires you to optimise your training in each zone and identifying where your weaknesses lie.
The shortest and simplest energy system to talk about is the ATP-PCr system, or the phosphagen system, or the alactic system. It has many different names but how it works is very simple (provided you've read the ATP article, if not read it here now). ATP is stored in the muscle. Molecules of phosphocreatine (PCr) are also stored in the muscle cells. A key component of PCr is the phosphate bond attached to it. During intense activity, ATP molecules are used resulting in an increase in ADP within the muscle. To restore this back to ATP to provide energy for continued muscle contractions, the phosphate bond is broken off from PCr and added to ADP to create new ATP (see below). 1 molecule of PCr can provide 1 molecule of ATP for use during energy, which is why this system is depleted quite quickly. It needs time to replenish the PCr stores in the cell before you can perform at the same intensity. This also sheds light on why creatine supplementation is useful for athletes. More creatine in the muscle means greater opportunity to produce ATP for high intensity muscle contractions.
So, that's the first initial introduction to energy systems. Once you have a better handle on all the different types of energy systems you can start to think deeper about how to practically go about developing them as part of a long term training programme. Just remember, every movement requires energy so at any point in time you are using various energy systems. Whether it's lifting weights in the gym or out running on the pitch - it all adds up.
Stay tuned for the next article when we look specifically at the glycolytic system.
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