Power = Strength x Speed

We have seen that aerobic power, or VO₂Max, can be measured via the "Åstrand test". Both the "PWC test" and the "Conconi test" involve other factors -- power and strength. When we talk about stamina, we often use terms such as power and energy. What do these terms mean exactly?

Example: When you fill up your car with gas, you are giving it energy. The amount of fuel corresponds with the amount of energy (number of km). With this example, we can also determine how much energy is used per unit of time -- or the amount of fuel the car needs per minute. Power is the term used to describe energy per unit of time.

But why is the foregoing so important? The total amount of energy tells us something about the total potential performance. The amount of energy, however, does not tell us how this performance will be delivered. The notion of power is needed to explain this. A high-powered car will be able to travel 100 km faster than a car with less power.

The same thing applies to the human body. We derive a quantity of energy from our food, with which we can deliver 'total performance', for example, a time trial of 40 kilometres on a bike. When we talk about human power, we are talking about the speed that a person can travel on one's own for a longer period of time.

Endurance athletes have high-powered 'motors'. People with poor physical conditions are typically low powered. Ironically, these same persons carry huge amounts of energy around with them in the form of fat!

The latter example again illustrates that there is a major difference between energy and power. Unfortunately, both terms are often used interchangeably. To avoid any misunderstanding, we have given both notions different names.

• Energy is expressed in joules. Using joules or kilojoules, we currently calculate that one calorie equals 4.19 joules. Joules can be abbreviated using the capital letter 'J'. We also often see the expression KJ (1000 joules).

• Power = energy per unit of time and is expressed in Watts (W). This unit corresponds to the amount of energy delivered by 1 joule in a unit of time of 1 second. Therefore, 1 Watt = 1 joule/1 second.

We are therefore going to see how much power a person can deliver. To obtain a balanced comparison, we normally divide power by body weight (power to weight ratio). In this way, we can compare various people with each other.

With a Conconi test, we want to find a person's AT. However, simultaneously, we want to discover the power that this person delivers at this heart rate. In addition, we also want to know the maximum amount of power delivered. Here, too, the data found will be divided by the body weight, which will express the power delivered per kg/body weight (watt/kg).

In this case, the type of test protocol you use is important -- in other words, for the Conconi test in which the power is increased every minute (the test for untrained and trained cyclists), or for the Conconi test in which the power is increased every three minutes (the test for well-trained cyclists). Additionally, the increases per unit of time are also important: 20, 30, 40 or 50 Watts. Consequently, you should not compare the various tests with each other. Compare yourself with an earlier test.

With tests for untrained and trained cyclists, with an increase of 40 Watts per 3 minutes, the table below shows the power delivered at your AT:

With tests for well-trained cyclists, with an increase of 40 Watts per 3 minutes, the table below shows the power delivered at your AT: