Like the title suggests (and in similarity with the 30-15 IFT), the 45-15 test is a field test that utilizes 45-seconds runs with 15 seconds of passive recovery with a progressing running velocity and was invented by Castagna and colleagues (1 - see reference below) this year.
The purpose of this test was to elicit VO2max of the players in an intermittent manner.
The reliability and validity was tested in 18 young male soccer players through repetitive performance of the 45-15 test and another laboratory test. In this study, the results showed no significant bias between a) repetetive performance and b) the final speed in the 45-15 test and the maximal aerobic speed in a different test. The 45-15 performance was significant related to VO2max and the maximal aerobic speed.
All/many players can perform the test at the same time and therefore is a practical tool to assess players' aerobic endurance.
The running velocity of the final level was considered as the player’s individual performance for this test.
Due to its publication date (2013), we were not able to find any other published scientific research utilizing the 45-15 test and therefore we cannot give any further information, despite that Castagna and colleagues also state (small) normative data for their test - a score above 16.5 km/h seemed to possess good aerobic endurance.
1) Castagna, C., Iellamo, F., Impellizzeri, F.M., and Manzi, V. Validity and reliability of the 45-15 test for aerobic
fitness in young soccer players. Int. J. Sports. Physiol. Perform., 2013.