The data show the strong advances both Bol and Klaver have made in the last few years - they are taking full seconds off their PB each year outdoors (where there is more data). It also shows the big improvements generally from 2018 onwards (with a short interruption due to COVID) which we would attribute to improved shoe technology. Something which has also clearly benefitted Bol/Klaver. Also interesting is the improvement in times in 2005-2006 which then disappear - perhaps a result of a temporary hole in PED testing. The improvement in times in the early 80's are generally attributed to PEDs prior to he widespread introduction of testing.