TESTING DROP JUMPS When looking at reactive strength, there are few tests that are more effective than the Drop Jump. The aim is to jump as high and as fast as you can after stepping off a box or block. Your score of reactive strength index (RSI) is determined by how high you get divided by the time you spend on the ground. This is a great measure when looking at performance, power and rehabilitation, and is often used as a metric to determine return to sport status. If you want to get your RSI