Damon, ooohhh. Tough question. Let’s first review the purpose of easy Zone 1 and 2 aerobic work, and that might help you establish a protocol.
The purpose of the 80% of 80/20 training is two-fold:
1. To ensure that you are sufficiently recovered in between challenging sessions so that you can gain new fitness on the hard days.
2. To gain the aerobic benefits that can only occur at low intensity.
So, you need to ask yourself in those Zone 2 sessions: am I training within the Zone 2 range in a manner that supports those two goals?
Upper Zone 2 will certainly support goal #2, but upper Zone 2 might not always support #1.
If you can push the upper and of Zone 2, and are confident that it does not compromise your quality interval sessions the next day, then carry on. However, very few athletes have the self-awareness to know if they are sabotaging tomorrow’s workout by going too hard (even in Zone 2) today.
I hate to not answer your question directly, but it really depends on how you feel your quality interval sessions are going. If they are on fire, then no change required. If you are a bit fatigued, then maybe a week of mid to low Zone 2 is the answer.
David
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