D,
Thanks for using our plans!
The term “rest” day does not have an industry definition. For some, it means sitting on the couch all day, for others it means only cycling for 2 hours.
We define a rest day as a day of significantly reduced volume. You’ll note that in your Level 3 plan, every Monday is a swim-only day, and we define that as a rest day.
However, that swim can be moved or merged to make Monday a complete day off. Check out the comments on your first swim workout which states:
“Congratulations on your decision on taking on the Advanced Ironman Training plan! You have options for each Monday. Alternatively designed to be a rest day, strong swimmers can skip this day completely. Due to the short duration of the Monday swims, beginner and intermediate swimmers can combine the Monday swim with another swim during the week. Additionally, I recommend strength training be incorporated into your plan, see “Incorporating Strength Training Into Your Training Plan” at http://www.8020endurance.com/resources. Finally, unlike the cycle and run workouts, the swim schedule has a great deal of flexibility and swim workouts can be moved or short swims even merged at the convenience of the athlete.”
David