Thursday, January 29, 2009

The Significance of Measuring Power

Stimulus vs. Response:

A basic tenet in training is that there is a distinct relationship between an individual’s training load, or the training stimulus, and that person’s adaptive response or performance. This “Stimulus-Response” relationship is generalized as an inverted U relationship, where too little or too much stimulus results in sub-optimal performances. If you don’t train, you won’t perform, but if you train too much you also run the risk of hurting your performance.

Determining the optimal amount of training for a given individual is often the biggest single problem faced by an athlete. Until recently the tools to easily measure the training stimulus did not exist in endurance sports like cycling, where variations in wind, terrain, and drafting, make speed and distance an inconsistent measure of the training load.

Because power output is an absolute and objective measure of the training stimulus, the advent of power meter technology now makes it possible to accurately quantify an individual’s training load.

In the same way that weight lifters can measure the actual mass that they lift in the gym, cyclists can now measure the actual power they produce when riding.

Power (Stimulus) vs. Heart Rate (Response):

In the laboratory, there is a strong and linear relationship between power output and an individual’s heart rate response. As power output increases in a controlled lab environment, heart rate also increases in a predictable fashion. Because of this strong relationship between power and heart rate in the lab, heart rate became a common way to measure exercise intensity in real world conditions. This assumed, however, that the relationship between heart rate and power output remained the same outside the laboratory.

We now know that a number of factors can change the relationship between power output and heart rate in the “real world.” These factors include dehydration, heat stress, sudden changes in power output, fatigue, changes in a person’s fitness level, and the excitement of competition.

As a result, heart rate is not a good predictor of the training stimulus or power output in the field, especially in competitive events where power output can vary tremendously. This doesn’t mean that the heart rate response is un-important. It just means that the heart rate response is one of many physiological responses.

Power Output Provides Objective Feedback:

Ultimately, monitoring and evaluating power output during training and competition provides the most objective and immediate feedback about one’s performance.

Understanding your own response to training relative to an objective measure like power output takes the guesswork out of training because of direct, consistent, and immediate feedback.

Basic Principles Have Not Changed -- The Ability to Apply Them Has:

Training with power does not change the basic nature of training - you still have to work hard if you want to improve. But you can also work smarter by applying basic training principles that have been difficult to apply without power.


A fundamental training principle is that training should be as specific to the demands of competition as possible. That is, your training should replicate either in parts or as a whole what happens in competition if you want to optimize your training for a given event.

Using power, you can measure different aspects of a given race, such as the average power output, total energy required, and time spent in different intensity ranges. Your coach can then use that information to develop better training strategies and to monitor whether your training is specific to your competitive goals.


Another basic training principle is the idea of periodization - the balance between hard days of training [overload] and easy days of training [recovery].

In order to adapt, the training stimulus needs to be greater than recently experienced – overload. At the same time, any period of overload needs to be followed by a period of rest or recovery to allow the body to heal and grow stronger.

If done correctly, over time an individual’s training load looks very similar to a stock chart for a successful company. Despite periodic highs and lows, the general training load that person is able to handle continues to grow.

Creating proper periodization schedules was extremely difficult before cyclists could accurately monitor their training using power; like an unstable economy, evaluating the value of one’s training load was speculative at best.


A training program that works well on one individual may not work as well on another. This idea is called individuality and reflects the unique genetic attributes of each individual.

Because every individual may respond differently to training, to reach a given fitness or performance goal, it is important to develop techniques and strategies for a given person to quickly and efficiently experiment with their own training rather than adopting strategies developed or tested in dissimilar individuals.

Power technology provides scientifically accurate information that is specific to the individual user. You can figure out how a given training plan affects your performance rather than generalize from a program designed for a different person.

Next – my new toy . . .

No comments:

Post a Comment