Understanding Energy Systems and Performance

Every cell in your body requires an unrelenting supply of energy to keep you alive.

Energy systems are the way the body meets these energy demands.  Conditioning is directly related to energy production and expenditure.

Your body uses two primary energy pathways:

1.) Aerobic (requiring oxygen)
2.) Anaerobic (without oxygen)

Both of these energy systems are responsible for the production of ATPthe molecule which provides most of the body’s energy.

Energy production is so crucial to your survival that your body has several systems in place to regulate the process and make sure that energy demands are met smoothly, namely through homeostasis.

Homeostasis is the maintenance of the body’s internal environment within the required physiological ranges in the face of varying internal and external stressors.

Basically, homeostasis regulates what happens inside the body under the purpose of continued energy production and delivery.

From a big picture perspective, every adaptive response to the body’s environment is to maintain homeostasis and to continue producing energy in that specific environment.

There are three variables that define the type of environment that your body perceives: 

1.) Rate of energy production

When there is a high rate of energy production required, the activity is anaerobically dominant.

High rate = High Power output

  1. Track and Field-jumps/throws/sprints
  2. Weightlifting 
  3. Power lifting 

2.) Duration of energy production

When there is a high duration of energy production required, the activity is aerobically dominant

Duration = economy/efficient

Endurance events

  1. Triathlons
  2. Cycling
  3. Marathons

3.) Work-to-rest ratio

When there is a high level of work with only a small amount of rest, the activity is aerobically dominant

These three variables can be understood within the context of the force-fatigability relationship, that as the maximum rate of energy production increases, the maximum duration of energy production decreases (and vice versa).

Understanding the simple yet powerful concept of the anaerobic power reserve is absolutely essential to getting to the heart of how energy systems and performance are related

Today, it is accepted that the energy provision for every effort relies on the simultaneous participation of all three energy pathways with a predominant pathway working above the others

Explosive Efforts: all-out exercises with a duration of up to 6 s (predominance of phosphagens pathway). 

High Intensity Efforts: all-out efforts lasting from 6 s to 1 min  (predominance of the glycolytic pathway in addition to the ‘phosphagen’s pathway and ‘oxidative phosphorylation’)

Endurance Intensive Efforts: exercise with a duration exceeding 1 min (predominance of ‘oxidative phosphorylation’).

There is a trade off between the duration of an activity and the amount of power you can exert.

Different energy systems are capable of producing ATP at different rates and for different durations.

The two anaerobic systems (glycolysis and phosphocreatine hydrolysis) are utilized most for short duration activities with high power output.

The more efficient aerobic system, on the other hand, is capable of producing a lower power output for a much longer duration.

MYTH: anything explosive or requiring a massive amount of strength is an anaerobic event.

Not necessarily: the aerobic system predominates in activity lasting more than around 50 seconds, even though you may still be explosive or strong.

The contribution of the aerobic system to energy production increases over time.

What about events with repetitive tasks or movements (football, MMA, etc.)?

As an action/activity is repeated over and over again, it becomes more and more aerobic, which is why you slow down with each repeat.

Consequently, it’s not surprising that most team sports have a huge aerobic component to them.

During all-out, max effort activities, the crossover to aerobic dominance occurs at around 20-30 seconds.

So how much speed/power does the anaerobic component account for? 

Different people are able to produce a different amount of power anaerobically versus aerobically.  This difference is called the anaerobic power reserve.

Anaerobic power reserve= max speed – max speed produced aerobically

Don’t get confused by the equation: the anaerobic power reserve is simply the portion of your max speed that is not produced from your aerobic energy system.

The amount of your max speed produced aerobically versus anaerobically can predict how soon you will fatigue:
Those with a larger component of energy coming from the aerobic system are able to maintain speed a lot longer than those with a larger anaerobic component.

A lot of runners sabotage their training by allowing their long runs and easy runs to become anaerobic, and this can sacrifice future races, as well as future workouts

 Improving aerobic fitness is one of the most important concepts when it comes to training in general.

Your capacity for improving the aerobic system is much greater than the anaerobic system.

This is because there are 3 factors that contribute to aerobic fitness, all of which you can manipulate:

1.) Oxygen supply
2..) Oxygen utilization
3.) Substrate availability

In order to talk about training aerobic fitness, we must broach the controversial topic of training intensity…

If you look at only a short period of time, the body adapts quicker to high intensity training (it provides a stronger stimulus).

However, if you train beyond 4-6 week at a high intensity, you are going to see higher rates of plateauing and overtraining.

Moderate and low intensity training produce less significant improvements in the short run but greater and longer lasting improvements over the long run.  

When it comes to actual aerobic training methods, there are a couple of basic principles:
1.) Heart rate should be below anaerobic threshold
2.) The lower the intensity, the higher the volume
3.) Aerobic fitness can be improved through steady state or intervals

Now on to some actual training methods…

Cardiac Output:
Goal: increase the left ventrical size and improve slow twitch muscle fiber endurance

Key Characteristics:
HR in the 130-150 bpm range
30-90 minutes of activity

Tempo Intervals:
Goal: increase capillary density and oxidative abilities of slow and some fast-twitch fibers

Key Characteristics:
8-10 sec work (70% of max intensity), 60 sec rest
8-16 reps
moderate intensity

High Resistance Intervals:
Goal: improve endurance of fast-twitch muscle fibers

Key Characteristics:
high resistance- incline or load
short work period ,5-6 sec
rest until heart rate is in the 130-160 range
moderate-to-high volume

improve aerobic fitness


In fact, it’s one of the most important concepts when it comes to training in general… 

How to Build Explosive Power 

There are two parts to the anaerobic system, both of which produce energy much faster than the aerobic system.

Furthermore, during a 400-m all-outrun of about 52-s, the last 20-s of effort is performed at VO2max, showing that the activation of ‘oxidative phosphorylation’ is much faster than previously thought [21]. Today, it is accepted that the energy provision for every effort relies on the simultaneous participation of all three energy pathways with a predominant pathway working above the others [21]. 

1.) Alactic (Mostly explosive but only produces energy for a few seconds)
2.) Lactic

The cost of such rapid energy production is that it leads to fatigue much faster and you’re not able to sustain high power output as long.

When it comes to actual anaerobic training methods, there are a couple of basic principles:

1.) Intensity should always be greater than 90%
2.) Use longer rest periods for developing max power and shorter rest periods for improved capacity
3.) Anaerobic training is about much more than just fatigue

We see these principles reflected in the following anaerobic training methods:

Alactic Interval Training:
Goal: increase rate and capacity of lactic energy production

Key Characteristics:
3-6 sec of work, 60-120 sec rest
10-20 sets
Use exercises intended for explosive strength and power training

Lactic Interval Training:
Goal: increase lactic energy production and anaerobic endurance

Key Characteristics:
30-40 sec of work, 1-4 min of rest
2-5 sets
1-2 series

Rest longer for lactic power, shorter for lactic capacity

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