I'm doing a couple of triathlons, I can ride and run OK, and am comfortable swimming, but reckon I can improve. For instance my "comfortable" 700m open water swim (I live by the beach, the 2 nearest groins are 350m apart) takes 15 mins, but my ave HR is 130 or so, when it's easily 150-160 running/riding.
My guess is my HR is low because mr CV system is way ahead of my swimming muscles, and also my power is limited by slow breathing?
My tactic si to swim 2-3 times a week, once in a pool-based training session, building up distance towards the 3.9km of my event. Does this make sense?