PPO is a measure of the maximum force exerted at a certain velocity, generally within a time window of 5–30 seconds.
People’s PPO is often tested by having them cycle as fast as possible on a cycle ergometer. Once they surpass the flywheel’s inertia (whether state of rest or uniform motion), a load is applied and data is collected.
How much of the energy expended during the test derives from aerobic metabolism depends on the duration of the test — the longer the test is, the more aerobic it is. If the test lasts 30 seconds, aerobic metabolism can account for about 20% of the expended energy.