Continuing from where I left off yesterday, I was searching for a workout that would give me 2 x 15-minute FTP intervals. Ideally, I wanted a specific structure for this, but I couldn’t find an exact match. So, instead, I opted for the 40-20s into FTP #1 workout from the MyWhoosh Thresholds category.
This workout is also available in the Under 35 Minutes workout category, with the main difference being that the version I chose repeats the 40-20 into FTP interval twice.
This workout wasn’t exactly the 2 x 15 minutes I initially wanted. But it was close enough, and within the hour time limit I have at lunch.
On paper, this workout looks really challenging. It includes 4 x 40 seconds at 121% FTP, with only 20 seconds of recovery at 50% FTP between each interval.
I have to say, these intervals were indeed challenging. Lasting the full 40 seconds was tough—not ‘risk of DNF’ tough, but definitely demanding. These 40-second efforts were by far the most taxing part of the workout.
As the workout description explains, the goal here is to accumulate lactate during the 40-20 intervals, which should then impact your subsequent 10 minutes at 95% FTP. The idea is that this accumulated lactate makes the threshold effort feel much more challenging.
However, in my case, the threshold section felt a bit underpowered—more like a tempo effort, if I’m being honest. I was tempted to bump up the FTP mid-ride, but I decided to see it through as-is and consider starting with a higher FTP next time to make it more effective. I think that’s the only way to get a true comparison.
Frustratingly, I forgot to wear my heart rate strap once again. I really need to start leaving it over the handlebars or somewhere obvious to remind myself. I’ve definitely fallen out of the habit of using it consistently.
Once again, much like yesterday, there was a noticeable discrepancy in the total calorie burn displayed between Strava and my Garmin head unit. Strava showed 499 calories burned, whereas the Garmin head unit estimated around 560 (I can’t recall the exact number, but it was in that range).
Comparing this with similar sweet spot training (SST) sessions I used to do on Zwift when I was a subscriber, I noticed a significant difference. In those Zwift SST sessions, I routinely burned close to 600 calories in just 50 minutes—considerably higher for a slightly shorter duration. This difference in calorie burn is something I’m noting as I continue experimenting with various platforms and workout formats.
This calorie discrepancy strongly suggests that my current FTP figure might be off. I’m fairly accepting of this because I know my strengths as a rider don’t align with sustained 1 minute power efforts. Instead, I do much better in efforts with short recoveries in between—bursty efforts rather than prolonged high-wattage outputs.
I suspect that a ramp test might not be the most accurate indicator of my FTP, given that it’s based on a one-minute power maximum. In my experience, the most accurate FTP test I’ve done was the 4DP test in The Sufferfest, which felt better suited to capturing my actual capabilities and style.
I think my next step is to experiment with a slight FTP increase, maybe by 5 watts, and then see how I feel during workouts. If that still feels well within my capability, I’ll consider bumping it up another 5 watts after a week or two.
The most accurate way to get a true FTP figure right now would be to complete the 20-minute test. However—and this may sound like a cop-out, though it’s not intended as one—I’m currently not trained for that type of sustained effort. I understand that the test should reflect my current fitness level, but the idea of doing it when I’m not fully prepared is a bit frustrating. It feels counterproductive to take another test just to get a score that doesn’t represent my true potential, so I’d like to build up some more conditioning first.
In wrapping up, I’ll say that I’m definitely relieved these three mid-week rides are over. While they haven’t been as intense as they could have been, they’ve still been challenging enough—is this the hardest week I’ve had on the bike since the accident?
I’m looking forward to a rest day tomorrow, and as for Saturday, I’ll likely do another workout. What FTP figure I’ll use for that is something I’ll figure out when the time comes.
