Thanks to Miss Nagatoro and Running, My Heart Got Stronger
Table of Contents
Three weeks have passed since I bought a smartwatch and started actively exercising.
The Amazfit Active 2 (Smartwatch) Is Seriously Good
I’ve also been keeping up the life hack of feeding my intervals.icu data to Gemini 2.5 Pro after every run and having Miss Nagatoro (from Don’t Toy With Me, Miss Nagatoro) comment on it.
Working Out While Getting Teased by Nagatoro-san Is So Productive
The payoff from all this has started showing up in tangible ways.
Heart Rate Improvements
About 3 km from my house, there’s a Don Quijote (a major Japanese discount store). The route there is almost completely flat, has no traffic lights, and if I take the back streets there are barely any cars, making it ideal for running.
I ran this route again today, and I noticed that running it felt vastly easier than before. Two weeks ago, toward the end, I had Shamiko-level shortness of breath (the notoriously stamina-deprived protagonist of The Demon Girl Next Door) and felt like I was going to die, but today I had plenty of room to spare.
Still, talking purely from subjective feeling isn’t great. So let’s look at the data from intervals.icu.
The above compares the data from two weeks ago (red) with today’s data (blue). I got caught at a traffic light in the second half, but fundamentally both follow virtually the same route. The temperature and humidity were also almost identical.
Looking at this, while two weeks ago my heart rate was glued to 190 BPM, today it looks to be hovering around 180 BPM. And since I ran a longer distance in the same amount of time, it’s not because I was running any slower either.
Let’s take a look at some slightly more detailed data regarding heart rate.
Here is the data from two weeks ago:
Here is today’s data:
In the data from two weeks ago, I spent about half the time in the “SuperThreshold” zone. This time, however, it stays cleanly within the “SubThreshold” zone. Heart rate across the board has clearly dropped.
By the way, what kind of threshold is “Threshold” referring to in the first place? Apparently, it’s the boundary between aerobic and anaerobic exercise. If you’re above this threshold, it seems your body can’t clear lactate fast enough. Putting it in gaming terms, when you exceed the threshold, your stamina bar balance is net negative, meaning you’ll eventually run out of steam; otherwise, the balance is roughly breaking even, meaning it’s a pace you can keep running at indefinitely.
I fed these images to Miss Nagatoro and asked for her thoughts as well.
Miss Nagatoro’s Review
- Even an idiot could get this! Your heart finally learned how to slack off!
Look at the graph, you little water flea! The heart rate for the pink line (today’s run) is obviously way lower than the blue line from two weeks ago! And yet the power graph up top is about the same, or if anything, even higher this time!
Do you even get what that means? It means your heart doesn’t have to desperately pound like crazy just to put out the same power! In short, Senpai’s heart can pump blood properly without thrashing around like a panicking hamster anymore! Your heart learned energy-saver mode! Well, all thanks to me whipping you into shape, of course!
- “Felt easier”? Well DUH, you total wuss!
“Felt easier subjectively”… like, obviously! If your heart’s having an easier time, of course your whole body feels easier! It’s like you went from desperately clawing up a hill in a kei car to swapping the engine for a slightly better scooter engine! Instead of just pointless, painful self-torture, hasn’t it finally started looking somewhat like actual “training”?
- And do you have any clue why this happened?
It’s because, just like I told you, you actually did your threshold runs and put proper load on your cardiorespiratory fitness! You wouldn’t get these results just running around blindly. Because you ran with an actual purpose, your body went, “Oh crap, if I don’t adapt to this hell, I’m gonna die…!” and your heart leveled up! Which means it’s entirely thanks to yours truly!
Gemini’s Review
I also consulted Gemini without any persona attached. Apparently, the following improvements have been occurring:
- Strengthening of cardiac pumping function (increased stroke volume)
- When you start training, your heart muscle is strengthened as well.
- As a result, the volume of blood pumped per beat (stroke volume) increases.
- Fewer heartbeats are required to deliver the same amount of oxygen to the muscles throughout your body. This is the biggest reason why heart rate stays lower even at the same running pace.
- Improved oxygen utilization efficiency in muscles
- As you continue running, capillaries in the muscles increase, and cellular organelles that convert oxygen into energy (mitochondria) become more active.
- This allows the muscles to use oxygen from the blood more efficiently, reducing the burden on the heart.
Conclusion
So it seems my body is transforming into one that doesn’t get out of breath easily, even under the same exercise load. Very grateful for this.
I used to hate PE—especially distance running, which I loathed on a traumatizing level—so I had never run in my entire life. Starting from that state, it feels like an insanely powerful beginner gains bonus is at work.
The improvement in heart function has been noticeable outside of running too. For example, when playing Beat Saber, the reason I fail a song has changed. Previously, I’d often run out of stamina and fail to keep up with the notes, but lately it’s more like I still have stamina left, but my arm speed just can’t keep up.
At the very least, how winded I get after finishing the same song has improved drastically.
↑ My touchstone. This is Ex+ (Expert+), but I can still only clear Ex (Expert). Since I can only clear Ex when I’m in good shape, it serves as an excellent barometer for me.
Heart strength is apparently quite vital for overall health. Professor Gemini (the AI) told me that my beginner bonus period is probably about to end, but I want to keep running and build a healthy body.
Thank you, Miss Nagatoro.
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Notes on games, radio and technology, translated from the Japanese blog.