Seinstra is a chartered accountant with Deloitte. He was treasurer for the SHT from 2007. In this position he was active until the end of 2011. Seinstra also helped organize the World Championship Triathlon in 2008.
The SHT announced in January that it has started a partnership with the Challenge Family.
The Holland Triathlon has joined into a famous series of large triathlons. The Challenge Almere-Amsterdam will be held on the weekend of 13, 14 and 15 September.
,, The Challenge Almere – Amsterdam is for Almere a great challenge,” says Seinstra.