What is Power?

Firstly, let us clarify some terms. Power is the amount of work one performs over a certain amount of time (Work/time) while work is a function of resistance to movement and distance (Force x distance). There are therefore three ways to increase power output:

1. Increase force production
2. Increase the distance travelled
3. Reduce the time it takes you to perform a given amount of work.

An example of how power can be applied to endurance sport, would be cycling a 40 kilometer time trial. As the work is constant for all participants, those who perform the time trial in a faster time have therefore had to elicit a greater power to do so.

All endurance sport follows this principle, the faster you wish to perform a given amount of work, the more power you will need to produce to do so.

Power = Work/Time

The "power"you need to elicit is referred to as external power as it is the power needed to move an object (your body) the entire distance of the race. The energy used to produce external power is derived from a series of biochemical reactions in your working muscles. As no machine is 100% efficient, it takes a great deal more internal energy to perform the external work. Internal energy can also be referred to as power as it describes the amount of internal energy production (i.e. internal power) required to perform the external work. In endirance sport, we refer to internal power production as "Aerobic Power".

This energy can be supplied from distinct energy systems within the human body, and for exercise lasting greater than 3 minutes the main system is our “aerobic system”. This system uses oxygen to produce energy, which in turn is used to perform muscular contractions that ultimately produce external work. The faster one can produce energy to perform muscular contractions (i.e. increase the rate of energy production) the faster the rate of external power output.

Simply put, the faster you wish to run, ride or swim, the faster you need to produce energy. As endurance sport involves competitions lasting longer than 3 minutes, the most important energy system is again the Aerobic System.

What is Aerobic Power?

“Aerobic Power” refers to the maximal rate at which you can consume oxygen. It is commonly referred to as V_O2^max and is the gold standard measure of a person’s fitness. It is typically reached during maximal runs lasting 10-12 minutes (3 km race pace for most endurance athletes, but can be attained as quickly as 3 minutes, if performed at an appropriate intensity. Endurance events can therefore be classified into intensities at varying percentages of our Aerobic Power. As you are well aware the relationship between duration and intensity of exercise is linear and negative. The longer the duration, the lower the intensity. For endurance purposes, we will associate Aerobic Power with the speed you can hold if I asked you to cover as much distance as possible for 6 minutes. This will serve as the pinnacle of race intensities, with all other races being performed at a fraction of this intensity. We use the following continuum to describe the varying percentages of Aerobic Power where you may find your endurance events.

The colors represent the intensity of the exercise, such that yellow represents low intensity while red represents increased exercise intensity.

The percentages obviously vary based on your training status, as elite marathon runners have been shown to race at intensities as high as 85% of their Aerobic Power, but for the most part they are similar between most recreational athletes.

What we at APTS have noticed in the athletes that present themselves for Aerobic Power testing (i.e. V_O2^max testing) is that a great number of them are very efficient at the yellow end of this continuum and are unable to perform well at higher intensities or shorter distances. These athletes may be described as “one-speed wonders” as their paces for their personal best times are quite similar from short distances (5-10 km of running) through to the longer distances (half-full marathon). We have therefore developed an approach to coaching the combines:

1. Physiological testing to ensure individualized training intensities,
2. Periodization to ensure we develop all aspects of the metabolic continuum
3. Interaction with our athletes, to guide them through this new approach to training.