This is an off season plan for athlete who are looking to improve times in IRONMAN or70.3 races. It is a competition phase plan that n focuses on nuero-muscular facilitation and V02 max training. It should lead to improvements in running and cycling economy and muscular power.
As the plan is based on the polarised training model it is important that easy sessions are kept very easy but when completing the V02 intervals it is equally important that they are at a sufficient level of intensity. By the end of a hard set you should be at a point where you couldn't do another rep at that pace.
If you have to miss sessions ensure that you prioritise the harder sessions and cut the zone 2 sets. However, make sure you allow at least 2 sleeps between hard sessions. This will ensure you can recover and work hard in the next session.