Sweet Spot and Ultra-Endurance

This is yet another question about SS and weight lifting, this time for ultra-endurance riding. I am doing SS Base 1, mid-volume, supplemented by one day/week of very hard lifting. The latter is non-negotiable bc I am rebuilding after a serious knee injury, which left me w a much weakened right leg. I find that, vis-a-vis muscle fatigue, the lifting is equivalent to an additional sweet spot workout, so I put it Wednesday morning, followed by the endurance-active recovery ride Wednesday night. But I am finding it hard to complete the Saturday threshold workouts, and sometimes even the Sunday sweet spot workout. I find I can do about two-thirds of the weekend workouts at target.

Before stating my question, here are my goals and profile: I am a 59 y.o. male, FTP 247, training for a x-country trip at 115 mi/day. My ultimate goal is x-country @ 150 mi/day @ ~ 17.5 mph. Don’t ask why, it’s a thing w me. I have done many multi-day rides but these will bump up the volume. I am not a racer and do not want to become one. I consider myself an endurance athlete.

So here is my question:

Should I: 1) drop some sweet spot workouts down to tempo or even endurance; 2) shorten the SS or threshold workouts but keep them at the target rates?; or 3) combine these two approaches by, eg, aiming for the lowest SS targets—88% instead of 94?; 4) something else altogether?

Thank you. I am very grateful for any wisdom, and a great believer in TR and this forum, both of which I have found exceedingly useful.

Sent from my iPhone

I would do endurance wo but longer

Another option would be hang in for the weekend threshold and sweet spot sessions as long as you can and then add 30+min of aerobic endurance at 60-70% FTP.

The lactate buffering and muscle endurance aspects of the weekend rides are important and I’d be very hesitant to completely remove them.

Thank you both for weighing in. For years, I followed Marc’s position and all but lived in Zone 2, which will certainly get you through a multi-day ride. But since starting sweet spot training on TR, and combining it w carefully planned lifting,
I have been v impressed w both aerobic and muscle endurance gains. My resting HR is lower than ever and my leg strength is at levels I have not seen in quite a few years.

I think the advice to hang w the toughest workouts as long as I can but then finish the ride w endurance work is well taken.

Thanks again.