What is a key characteristic of the multistage fitness test?

A key characteristic of the multistage fitness test, often referred to as the beep test, is that the bleeps become increasingly close together as the test progresses. This structure is designed to gradually increase the intensity of the exercise, requiring participants to run faster in response to the bleeps. The test starts at a slower pace, allowing participants to warm up, but as the levels advance, the time between the bleeps decreases, which reflects an increase in the aerobic demand on the body. This progression helps assess the cardiovascular fitness and endurance of the individual.

As for the other options, they do not align with the fundamental design of the test and how it measures fitness levels. For instance, increasing rest periods or requiring participants to run solo would not effectively reflect endurance capacity, which the test aims to measure.