The Critical Power is a well-researched concept to assess a physiological threshold, which is similar to FTP, in the field through sheer power output. In contrast to FTP, Critical Power is based on multiple max efforts of shorter and longer duration. This in turn, can help you better track progress and changes in fitness and individualise your threshold training to a greater extend.
Research has found that Critical Power occurs close to the second lactate threshold (LT2), which further underpins its physiological meaning.
This testing manual includes the most common test protocols for Critical Power, explains its concept, and supplies you with the research studies behind it.
It can be used alongside my training plans to substitute field testing in my plans with Critical Power Testing.

As a small bonus I added two of my favourite interval workouts to the manual. Happy testing!