Yesterday I attended a BASES workshop focusing on critical power. Essentially it is a performance measure that gives a level of training intensity that is maintainable for somewhere between 20-40 mins. Theoretically it should be the same as your maximum lactate steady state (MLSS) but it tends to sit a little higher in the severe intensity domain. However, those utilising it tend use a further zone classification between the heavy and severe zones, imaginatively titled the ‘very heavy’ zone.
The test itself requires three maximum effort tests of varying lengths between 3 and 15 minutes long (3, 7 and 12 minutes seem to be the most common). These tests usually take place on the same day with 3 hours recovery between each one. With the average power data you can plot a graph against time and get a measure of critical power.
The measure lends itself particularly well to cycling given the familiarity with wattage as a measure of training intensity, however it is possible to take the tests using a set distance or time that is more applicable to runners and swimmers where taking of MLSS is very difficult to achieve. The information is very communicable to athletes given the graph produced and units are simple to understand. The value is also great to use for prescription of intensities when designing training sessions.
A certain amount of familiarity needs to be developed with the test in terms of pacing strategy which can skew early tests (those who’ve used the cooper test will be familiar with this) and the large recovery periods and requirement for full day to test could make the test inconvenient compared to a MLSS test which essentially gives a similar measure. It was mentioned that it had been trialled within an hour with similar results to the full day testing. If this proves reliable then I think the test becomes much more usable, primarily in cycling and swimming.