What is a running test used to estimate an athlete's aerobic capacity called?

The multi-stage fitness test (MSFT), also known as the beep test, bleep test, PACER (Progressive Aerobic Cardiovascular Endurance Run), PACER test, FitnessGram PACER test, or the 20 m Shuttle Run Test (20 m SRT), is a running test used to estimate an athlete's aerobic capacity.

The test requires participants to run 20 meters back and forth across a marked track keeping time with beeps. Every minute or so, the next level commences: the time between beeps gets shorter; participants must run faster. If a participant fails to reach the relevant marker in time, they are cautioned. A second caution ends the test for that runner. The number of shuttles completed successfully is recorded as the score of that runner.

The test is used by sporting organizations around the world along with schools, the military, and others interested in gauging cardiovascular endurance, an important component of overall physical fitness.