Test: Row (on an erg or upright) using good technique see how hard it is to arrive at full compression with hammies and glutes fully loaded.
Mwod: 1) Contract relax that high hammie 2-3 minutes each side. Keep seeking our difficult ranges
2) Active Tack and Stretch that high hamstring tissue while seated. 1min each side
Re-test: Try pulling your 500 m split now.

http://www.mobilitywod.com/2010/09/episode-28-better-rowing-high-hamstrings-part-1/
http://www.mobilitywod.com/2010/09/episode-28-better-rowing-high-hamstrings-part/