Is the SPLITS essential to a competitive swimmer?

I think my hampstrings are engaged at every wall. Tightness and cramping in the hampstrings has long been an issue for me.(my work involves lots of heavy lifting) During the manhattan marathon swim this year, i was forced to resign after about 16 miles due to hampstring cramping.

I think my hampstrings are engaged at every wall. Tightness and cramping in the hampstrings has long been an issue for me.(my work involves lots of heavy lifting) During the manhattan marathon swim this year, i was forced to resign after about 16 miles due to hampstring cramping.