Critical Power

myWindsock uses W’ Balance to help you pace race efforts correctly. W’ Balance allows you to maximise the work done above critical power (CP), but what exactly is CP? 

What is CP?

Critical power is the idea that the power duration curve can be fit to an equation which is approximately true for all athletes. Obviously, it’s more true for some athletes than others (there are statistical anomalies in any population). The point at which this approximation is no longer true will be somewhere between 30-60 minutes where the curve will tend toward a straight line – this line is where your critical power sits. 

The area between this curve and the CP line is your W’ – this is the amount of energy you have available above your critical power. You can use it all in one go with a big sprint, or burn it slowly with extended time just above critical power. 

How do I test it? 

You can test your critical power by doing two power tests and fitting a curve to the results of these tests. High North have quite a neat CP calculator available on their website. The favoured duration amongst coaches seems to be 3 minutes and 12 minutes. If you’re a 10 mile time trial specialist you might wish to do a 20 minute test as this is closer to race duration. Having more data points will also mean your CP value is more accurate so doing 3 tests might be better.

The W’ Balance tool

A more detailed description of how this works can be found here but we shall briefly discuss the tool here.

You can see in the graph that time spent above Critical Power depletes W’ and this is why having an up to date CP value is important for pacing – you don’t want to risk blowing up before the end or finishing with lots in the tank. 

If you like pacing tools and racing with confidence, you can sign up to myWindsock here! If you want a more detailed explanation of Critical Power, or any other metric on myWindsock get in touch with us via our social media.