MW22
For a solid sub 12 IM, speed work is pointless until you can knock out the ironman basic week without it killing you.
Once you have built your endurance to do that at z2 effort, then you can start to through some faster efforts in
Basic IM week in build period
- 75 m swim
- 6 hr bike
- 2.5 hr run
These are in seperate sessions accross the week.
If these wipe you out then just keep building base endurance
If these feel ok, start adding 30 min steady blocks into the runs, or 3*30 min upper z2 on the bike.
In the mean time, do at least 1 interval / turbo session a week, This complements the long ride, adding power to the muscular endurance from the long ride.
Lastly, how have you set your zones? Ones based straight on a % of max hr are as likely to e wrong as right.
Friel uses a 30 min functional test (max sustainable hr for 30 mins) to give a baseline then you plug that figure into a table and it gives you z1- z5 etc etc
You need to seperate tests for running and biking
And you need to repeat these on a monthly basis as things change.
This is quite a good read I found today about the benefits of base training and why it works
base training