I guess what it comes down to is the manufacturers interpretation of what line the blank is suited to, a 37KG rod will take a bit of bending, especialy if you are doing it "stand up", most rods are almost impossible to break by just "fishing" it is just not possible (almost) to exert enough pressure to break it (I said almost) nearly all rod breakages are caused by an "injury" earlier on, or high sticking (especially with graphite "blends"