The following table shows the World Record Progression in the Men's 50 km Walk, as recognised by the IAAF.
Note
The 3:35:29 by Russia's Denis Nizhegorodov set in Cheboksary on June 13, 2004 was not ratified by the IAAF as a World Record because no EPO test was carried out afterwards.
References
Men's 50 kilometres walk world record progression Wikipedia(Text) CC BY-SA