Since I am injured and can neither run or bike for the next weeks, I am focusing on my swim. I am stuck in the 4:40-4:45min range 400scm for the past few years. I swim usually 10-20km a week but had a bit of a break from swimming this summer/fall from august to november since I focused on cycling before my injury. I just started again and swam two weeks with five sessions and around 25k in total per week.
I am already back in around 4:50-4:45min shape I guess from recent workouts. Now how can I improve another 10-20sec on the 400m?
I am swimming 5-6x and do two core workouts per week atm. Any specific sessions? Up the volume even more?