|Date of birth||20 February 1973|
|Place of birth||Norway|
|2008||Åkra IL (coach)|
|* Senior club appearances and goals counted for the domestic league only. † Appearances (Goals).|
He started his career in Åkra IL, and was signed by then-second tier club Djerv 1919 in 1990. Djerv 1919 were relegated in 1993, Grindhaug crucially missing a penalty kick in the last match of the season. Djerv 1919 then merged to form the new team FK Haugesund. Grindhaug had the honor of scoring the first league goal for the new club, and the club eventually found its way to the Norwegian Premier League, making its debut season in 1997.
Grindhaug played regularly until the summer of 1998, when his career was halted due to knee injuries. Following five operations, he returned to football in the winter of 1999–2000. He trialled at several clubs, turning down a contract offer from Beijing Guo'an before injuring himself in a trial match for Umeå FC. His comeback to football, thus, came on the third tier of Norwegian football for SK Nord. However, he managed to reclaim a spot in the FK Haugesund squad. He remained there until 1 November 2007, albeit struggling with injuries since February 2006. In total he scored 45 goals in 220 appearances for FK Haugesund over two periods; only Arild Andersen has more appearances for the relatively young club.
Ahead of the 2009 season, Grindhaug was hired as the new head coach of FK Haugesund, replacing Rune Skarsfjord who left to become assistant coach in SK Brann. Grindhaug had at that time been a caretaker assistant coach for two weeks.
One month before signing Grindhaug, FK Haugesund had looked to hire Conny Karlsson; Other candidates were Roar Hansen, Jonas Wirmola and Kjetil Knutsen. Grindhaug, on the other hand, had worked in a coaching capacity at Åkra IL in 2008, however this contract was annulled due to a clause in which Grindhaug could leave for a bigger club. Grindhaug had formerly turned down an offer to be assistant coach of FK Haugesund in 2005.
- Grøttland, Odd Kåre (6 January 2009). "Dette er Jostein Grindhaug". Haugesunds Avis (in Norwegian). Retrieved 11 January 2009.
- Sortland, Gunnar Johan; Løvvik, Espen (6 January 2009). "- Ikke enkelt å takke ja til FKH". Haugesunds Avis (in Norwegian). Retrieved 11 January 2009.
- Hansen, Åse Karin; Jørgensen, Gisle (22 December 2008). "FKH får midlertidig trener" (in Norwegian). Norwegian Broadcasting Corporation. Retrieved 11 January 2009.
- Hillestad, Helene (8 December 2008). "- Vil ha Sparta-treneren" (in Norwegian). Norwegian Broadcasting Corporation. Retrieved 11 January 2009.
- Flateby, Terje (31 December 2008). "Fra Brann til FKH?". Haugesunds Avis (in Norwegian). Retrieved 11 January 2009.[dead link]
- "Nye trenere klare for Åkra". Haugesunds Avis (in Norwegian). 11 April 2008. Retrieved 11 January 2009.
- Flateby, Terje (6 January 2009). "Ansatte Grindhaug i går kveld". Haugesunds Avis (in Norwegian). Retrieved 11 January 2009.