It is used to measure a person's VO2max. (Maximal oxygen uptake). The procedure is used to measure the maximal endurance of an individual.
The test involves running back and forth between 2 marks 15m apart. These runs are synchronised with a pre-recorded CD, which plays beeps at set intervals. As the test proceeds, the interval between each successive beep reduces, forcing you to run quicker over the course of the test, until it is impossible to keep in sync with the recording.
The pass mark for this test is Level 5 Shuttle 4. Loughborough University conducted research and found this has to correspond with the minimum VO2max needed to be a police officer. To get to this mark, you must complete 35 shuttles in total, equalling a total distance of 525 metres. This takes approximately 3m 30 seconds to complete, and the pace increases gradually form approximately 4.9 mph during level 1 to 6.2 mph during level 5.
The test is near maximal, meaning that you carry on to about 95% of your capacity. You will only be stopped by the PTI if you look under severe stress or miss 3 consecutive beeps on the test.
You should undertake training that will increase your cardiovascular fitness. Such forms of exercise include cycling, swimming, rowing, using a stepper or x-trainer in a gym and running. Running is obviously the most specific form of exercise to the test, so should make up the bulk of your training. However, if you have an injury aggravated by high impact exercise, you may want to continue to build or maintain fitness with low impact forms of exercise, such as cycling. When running, try to incorporate 180o turns to simulate the test. This is much more demanding, especially on your legs, and will prepare you more than just running in a straight line all of the time. If possible, try to get hold of a bleep test, which can be purchased from local sports shops. These are usually 20m tests, but will give you a good idea of what is involved.
If you are unsuccessful on your first attempt, you may have two further attempts at a later date. You will be given a maximum of 6 weeks between tests to train and improve fitness levels, with the guidance of the PTI.