Your body today is completely different from when you were racing. This body has carried you through life and kept you alive and borne everything the world has thrown at you. Get to know what your body – this body today – needs, and compare your progress only to this time frame, not to your racing days. Plus, you’re right: what we understand about training has evolved considerably since then! What a cool learning curve to explore!
Good news! This isn’t an either/or question! You can try both approaches: increasing intensity vs. increasing volume. The trick is to move one lever at a time, and be patient enough to allow your body time to adapt to each change.
Fueling:
My best guess is that if you are completing fasted Sweet Spot workouts without fatigue, your power output is likely well below your actual Sweet Spot power. Fasted work is one of those “marginal gains” things that confers most benefit after you’ve built the foundation of your engine, which is to say, after you’ve increased your capacity to produce higher absolute power. Even then, pros will almost never do fasted work at intensities above endurance. You want to start with the basics, which will get you 90-95%, then later, after you’ve nailed that 95%, try the marginal gains for the extra few % (hence the term “marginal”). I’d hypothesize that fueling your workouts will give you the biggest return, and I’d recommend making this change first for at least a couple of weeks. Try having 40-60g CHO during your ride (e.g. 20g every 20 min, or space out your intake evenly between intervals, aiming for a relatively constant “flow” of CHO during the workout). I’ll bet what feels “easy” now will quickly feel ridiculous, and that you’ll find yourself capable of sustaining much higher power with less discomfort pretty quickly. I’d also be willing to bet this lever alone will result in FTP gains for you.
Intensity:
I also think you’ll make big gains with some VO2 work without increasing volume. The cool thing is that time in one training zone can affect your capacity across multiple zones. By adding some high end work, you’ll be able to increase your capacity across a broader range of zones than sweet spot alone. Since you have time constraints, I’d start by swapping in the VO2 work and see how that goes. You obviously don’t have a lot of time, or you’d already have been adhering to the training plan’s longer rides. AFTER you’ve tried fueling for at least two weeks without making other changes, THEN try subbing a VO2 workout for the longer scheduled ride each week.
I am very confident those two levers will result in vastly different outcomes for you. BUT if they don’t, the next thing to try would be sticking to the scheduled plan and doing the longer scheduled rides. You don’t need to add extra until you’ve just tried doing the plan as written.
More volume isn’t always the answer, especially when your body is already under a lot of stress (fasted training is crazy stressful on the body, and your busy schedule is probably limiting recovery). If you were coming off a few years of high volume training and racing, then volume would more likely be a limiter. It’s important to find what can work for you, given your individual constraints, which includes scheduling. I strongly advise that you aim to get the absolute most out of every hour on the bike right now, before you start adding on hours. If your time on the bike right now isn’t the highest possible quality (read: power output), adding more time isn’t the best answer. Quality over quantity.
The key is to be patient enough to adjust ONE thing at a time, and to give your body time to adapt. Don’t try to do all of things at once! Start with fueling. See how it goes. You’ll probably feel loads better. If that works for you, keep it going, and THEN add the VO2 work. Give that at least couple of weeks. In the words, aim to ONLY try these two things during SSB I. Then you’ll have a clear picture of which lever works best for you. If neither works, try doing all of the scheduled workouts (incl longer ones ) in SSB II.
Hope that helps!
