Just a quick and interesting preamble. I only recently became aware that we humans are at least partially solar powered. Here is a very diluted version of how: that giant, floating inferno we call the Sun directs 430 quintillion Joules of energy to the Earth – every hour! That’s 430 followed by 18 zeroes! In comparison, the total amount of energy that humanity uses in a year is 410 quintillion Joules. The earths flora (plant life) absorbs this energy via photosynthesis, converting light energy into chemical energy (Mostly carbohydrates and glucose) – allowing them to grow and bare fruit. The earths fauna (animal life) – herbivores and omnivores then eat this produce, which are then themselves eaten and so on. Most of this we learnt in school but I never fully appreciated this incredible process of energy transfer across or ecosystems and food-chains. The very ecosystems we’re more and more perilously at odds with.
Just as plants use photosynthesis to convert light energy into chemical energy, we humans have our own metabolic processes to convert consumed (or stored – in the form of fat) chemical energy into mechanical energy (movement). Whether your blinking or smashing out some squats; to create energy, in the form of force – you require energy, in the form of ATP. ATP is the bodies dollar (reserve currency) and is created via the metabolisation of glucose (carbohydrates) or lipids (fats). There a three systems through which this metabolisation takes place:
- The ATP-PC System – Anaerobic Alactic
- The Glycolytic System – Anaerobic Lactic
- The Oxidative System – Aerobic
The system been used is dependent on a number of variables. Namely, the intensity and duration of the activity in question. How seasoned the athlete will also influence which system is used and to what extent. Additionally, the bodies energy yield will depend upon multiplicitous factors, scilicet:
- The energy system development of an individual.
- Muscular size and fiber constitution. Bigger, stronger muscles both require and produce more energy.
- Nutrition – what you get out of the exhaust depends on what you put in the tank. There is more to food than its macronutrient make up. Chowing down some deep fried fish & chips before an ultra is likely not to be as effective as a pan seared cod fillet with a baked sweet potato and mediterranean vegetables, lavishly dressed in olive oil. The macros are almost identicle but the latter provides many more vitimins, minerals, digestive enzymes, and co factors that make it the preferable choice.
The table above helps to visualise a few things:
- The oxidative system fuels slow and enduring activity (including rest). Such as persistently tracking and hunting down your dinner over tens of miles at a steady pace.
- The PC system provides the energy (ATPs) required for short bursts of high-intensity activity. Such as would be required when decisively throwing a spear into your dinner to take it down from a safe distance after running it to exhaustion.
- Throughout the hunt, just like in training, sport, and life – the body efficiently taps in to each of these systems to ensure you receive the ATP you require to compete, train, and survive. For example, 10 miles in, you see that a competing predator has their eyes on your dinner. You communicate with your tribe to organise a trap and sprint into position before performing an explosive attack on the competitor. Once dealt with, your back on the hunt.
- The bodies energy systems are designed to maintain homeostasis (balance) and meet environmental demands.
Here’s a monetary analogy taken from Brett Bartholomew:
- Credit Card = ATP/PC – You can draw out a large amount of ATP pay an immediate, unexpected bill but expect to pay it back later on.
- Cash = Glycolytic – ATP is made available when you need it but doesn’t last very long and when it’s gone, it’s gone.
- Salary = Oxidative – A steady and reliable drip of ATP that if properly budgeted (paced), will last indefinitely as long as you keep working (eating).
The implications of this on sport and training are profound and the energy requirements of each sport or mode of training can be broken down into the following components:
- Rate of energy production: i.e. how quickly energy is generated throughout a period of effort. Therefore High Power = High Rate of production. Sporting examples requiring a high power output are Olympic lifting, 100m sprinting, or javelin etc… Such sports are highly dependent on the phosphocreatine system.
- Duration of energy production: i.e. the duration which energy production is required to be maintained. As presented in the table above, the grater the duration, the greater the dependence on the oxidative energy systems. Activities that require sustained and enduring power and are highly dependent on the oxidative systems are: running, cycling, walking, and swimming.
- There is a direct trade off between the rate and duration of energy production. The greater the duration, the lower the rate of energy production or power output. However, as previously alluded to, if your energy systems are well developed, each person has the capacity to extend the capability of each energy system and develop more power, for longer.
- Work-to-Rest Ratio: The ratio between the length of work and the rest period. Because the PC system is used for short burst of high intensity effort – it requires a substantial recovery period to replenish. Inversly, the oxidative system can be used for extended periods with shorter rest periods. The glycolytic system can be viewed as a middle ground with the bulid up of lactic acid (a by product that causes that intense burning sensation when smashing out 20 repetitions of lunges) been the main limiting factor, recovery been the time it takes to flush the excess of this by-product out of the system (around 2 minutes). Higher peak power and longer rest = greater PC/glycolytic contribution. Shorter rest periods and/or longer work periods = higher levels of oxidative contribution.
Over the coming weeks we will delve deeper into each of these systems and finish the series off by highlighting the practical training implications of this newly acquired knowledge. Until then, get some!
Brandon.