Time to Exhaustion (TTE), also referred to as time-to-failure, it is the time remaining, at a given work rate (power or intensity) before the given work rate cannot be maintained. For example, TTE at 500 W could be determined to be 60 seconds. This means that if you were to start an effort at 500 W, you could sustain it for 60 seconds before you wouldn’t be able to sustain 500W and reach a point-of-failure. From an MPA perspective, after 60 seconds at 500 W, MPA would be 500 W.
N.B. The term “exhaustion” is used but in many cases, particularly at very high intensities, failure is reached before the feeling of exhaustion. Say for example, that your TTE at 1000 watts is 10 seconds. After 10 seconds at 1000 watts, you would be unable to sustain 1000 watts. However, you could still produce just under 1000 watts and would not yet feel exhausted, despite the inability to sustain the power. TTE as used in this scenario but would more appropriately be termed time-to-failure and not TTE. TTE has been selected as it is a more familiar term and concept.