Dodgy hip flexors

Hi all, my club has just managed to get back on the water again after 2 months of land training (horrible flooding!) and my hip flexors are absolutely screaming. Does anyone else have issues with hip flexor soreness/tightness and any form tips for prevention? It's been a constant issue in my rowing career particularly on water and I'm at a loss! We are racing quite a bit this summer and I'd hate to be in pain for it