I Self-Tested My Lactate With and Without KATSUO STAMINA

I kept noticing my lactate levels during marathon training, so I ran a self-test on a treadmill to check it directly. I’m publishing the raw data from every session — with and without KATSUO STAMINA — exactly as it came out.

Why I Decided to Test My Own Lactate

I Was Already Managing My Own Lactate

I’d already been interested in the Norwegian method, and I’d been training with blood lactate control as part of that approach.

I bought a Lactate Pro 2 lactate meter back in 2023 and had been using it for treadmill lactate threshold intervals and similar sessions. In other words, I already had a habit of checking my own lactate numbers during training long before KATSUO STAMINA came into the picture.

I Was Honestly Skeptical When the Partnership Came Up

I’d known the name KATSUO STAMINA before, but I’d never looked into whether it actually worked — honestly, I’d just ignored it. It wasn’t until this partnership came up that I actually looked at the official site properly.

My first reaction was half-skeptical. If a supplement alone could lower your lactate levels, that would mean it could substitute for years of hard-earned lactate threshold improvement that recreational runners work toward. My honest gut reaction was: is it really that easy?

What the Evidence Review Turned Up

So the first thing I did was an evidence review using research databases (I go into detail in my KATSUO STAMINA product review).

I didn’t find any study that directly backed up the exact mechanism KATSUO STAMINA claims. That said, when you combine several related studies, you can’t rule out that the mechanism is plausible.

The manufacturer also showed me records of runners who’d used KATSUO STAMINA and seen their lactate levels drop. But I didn’t want to take that at face value — I felt I could only really be convinced by checking it on my own data.

Why I Decided to Test It on Myself

The Lactate Pro 2 was a device I’d bought in 2023 specifically to bring the Norwegian method into my own training. This time, I decided to use that same familiar device to run an incremental exercise test — pace increasing in stages — with and without KATSUO STAMINA.

Test Protocol

This test used an “incremental exercise test” format, where pace increases in stages. Treadmill grade was 0%. Here are the six pace stages:

Stage	Pace
1	6:58/mi (4:20/km)
2	6:26/mi (4:00/km)
3	5:54/mi (3:40/km)
4	5:38/mi (3:30/km)
5	5:22/mi (3:20/km)
6	5:06/mi (3:10/km)

Each stage: run for 3 minutes, then stop for 75 seconds for a fingertip blood draw and lactate reading. Repeat through all six stages.

There were three conditions: no KATSUO STAMINA (Control), 6 capsules, and 12 capsules. I ran each condition twice, for six total sessions, every Sunday. Keeping the day of the week fixed was meant to keep my weekly fatigue pattern as consistent as possible.

During the test period, I kept the rest of my training menu on its normal cycle without changes.

I recorded temperature and humidity before every session. Temperatures crept up slightly as the sessions went on (21.2°C for session 1 → 24.2°C for session 6).

On KATSUO STAMINA sessions, I took it right after waking up, then started the test after a warm-up. I changed this “time from dose to test start” partway through the experiment — more on that below.

Here’s what running the fastest stage (5:06/mi, 3:10/km) actually looked like.

Results

Test Conditions and Completion

I completed all six sessions: 2 Control, 2 with 12 capsules, and 2 with 6 capsules.

#	Date	Condition	Temp	Humidity
1	7/5	Control (none)	21.2°C	66%
2	7/12	12 capsules	21.5°C	59%
3	7/19	6 capsules	22.0°C	57%
4	7/26	Control (none)	22.9°C	50%
5	8/2	12 capsules	23.9°C	52%
6	8/9	6 capsules	24.2°C	56%

Temperatures trended upward as the sessions progressed. Even indoors, a treadmill isn’t fully insulated from the outside temperature, so later sessions may have been running under slightly less favorable conditions.

Lactate by Stage

Here’s the lactate reading (mmol/L) at every stage. Good numbers, bad numbers — all of it, exactly as measured.

Pace	7/5 (none)	7/12 (12 caps)	7/19 (6 caps)	7/26 (none)	8/2 (12 caps)	8/9 (6 caps)
6:58/mi (4:20/km)	2.4	2.4	2.8	2.2	2.4	2.2
6:26/mi (4:00/km)	3.2	3.1	2.6	2.6	2.8	2.4
5:54/mi (3:40/km)	3.8	4.0	2.9	3.2	3.0	3.0
5:38/mi (3:30/km)	4.1	missing※	3.9	4.1	3.5	3.5
5:22/mi (3:20/km)	6.1	4.8	4.6	6.3	4.1	4.3
5:06/mi (3:10/km)	8.7	7.4	6.9	7.9	6.1	6.3

※Only the 5:38/mi (3:30/km) reading on 7/12 looked out of line with the surrounding stages, so I’ve treated it as a measurement error and excluded just that one data point. No other stage or session was affected.

Here are the condition averages (2 Control sessions, 4 KATSUO STAMINA sessions):

Pace	Control average	KATSUO STAMINA average	Difference
6:58/mi (4:20/km)	2.30	2.45	+6.5%
6:26/mi (4:00/km)	2.90	2.73	-6.0%
5:54/mi (3:40/km)	3.50	3.23	-7.9%
5:38/mi (3:30/km)	4.10	3.63	-11.4%
5:22/mi (3:20/km)	6.20	4.45	-28.2%
5:06/mi (3:10/km)	8.30	6.68	-19.6%

At the 6:58–5:54/mi (4:20–3:40/km) stages, there wasn’t much difference in lactate between Control and KATSUO STAMINA sessions. But from 5:22/mi (3:20/km) on, where lactate starts climbing fast, the KATSUO STAMINA sessions came in clearly lower than Control.

Heart Rate and Perceived Effort

I also recorded heart rate at the same time. Here’s the heart rate (bpm) at each stage:

Pace	7/5 (none)	7/12 (12 caps)	7/19 (6 caps)	7/26 (none)	8/2 (12 caps)	8/9 (6 caps)
6:58/mi (4:20/km)	130	132	133	131	130	127
6:26/mi (4:00/km)	137	138	136	137	135	135
5:54/mi (3:40/km)	142	142	143	140	140	141
5:38/mi (3:30/km)	149	143	146	145	144	144
5:22/mi (3:20/km)	152	148	150	150	149	149
5:06/mi (3:10/km)	158	154	156	154	152	153

The gap wasn’t nearly as clear as it was for lactate. At the hardest stage, 5:06/mi (3:10/km), Control averaged 156 bpm versus about 154 bpm for KATSUO STAMINA — roughly the same.

Compared to the lactate shift (average 8.3 → 6.8), the effect on heart rate is unclear, and I want to be upfront about that.

I’ll also touch on perceived effort. This is my own subjective rating, not an objective number like the others, so read it with that caveat in mind — some bias is possible.

With that said, from session 3 onward, there were moments where it clearly felt “easier” to me.

How to Read These Results

What the Data Showed

This test covered six sessions total: no KATSUO STAMINA, 6 capsules, and 12 capsules, each run twice.

Starting with session 3 (6 capsules), I noticed a clear shift in both lactate and perceived effort. That same pattern showed up again in sessions 5 and 6, in the stages where lactate climbs fastest, up to 5:06/mi (3:10/km).

KATSUO STAMINA sessions came in lower on lactate in that pace range (5:22/mi, 3:20/km, and beyond), but there was almost no difference at the easier stages. I want to be upfront that the effect showed up differently depending on pace.

Things to Know Before You Read Too Much Into This

There are a few things worth knowing before you take this data at face value.

First, I changed my procedure for the time between taking KATSUO STAMINA and starting the test, partway through the experiment.

For the first 12-capsule test (session 2), I took KATSUO STAMINA right after waking up, did a 10-minute warm-up (a 5-minute walk to the gym plus 5 minutes at 7:15/mi, 4:30/km), and started the test 30–35 minutes after dosing.

Looking at that session’s results, there was almost no difference from the no-supplement condition at 5:38/mi (3:30/km) or slower, but lactate was clearly lower at 5:22/mi and 5:06/mi (3:20/km and 3:10/km), where lactate starts climbing fast.

Looking more closely at where that line falls, my own lactate threshold (LT) pace is roughly 5:54/mi (3:40/km). Below LT, the lactate-clearing effect wasn’t very clear; above LT, it became relatively clear.

Actually, the pace stages I used were based on an exercise-intensity proposal the manufacturer originally suggested, adjusted around my own LT to arrive at the final six stages:

Exercise intensity (m/min)	Pace
160	10:04/mi (6:15/km)
180	8:56/mi (5:33/km)
200	8:03/mi (5:00/km)
220	7:19/mi (4:33/km)
240	6:42/mi (4:10/km)
260	6:12/mi (3:51/km)
280	5:44/mi (3:34/km)

Terms like “low intensity” and “high intensity” mean different things depending on your own fitness level, so I think framing this around LT is more useful for readers of different abilities. That said, this “effect changes around LT” framing is still just one hypothesis at this point. I’d need more sessions clustered right around LT — on both sides — before saying anything more definitive.

Since the difference seemed to grow later in the test — meaning more time had passed since dosing — I started wondering whether 30 minutes wasn’t enough time for the effect to fully kick in.

I actually checked with the manufacturer on this, and they told me the product is thought to start taking effect roughly 45 minutes to an hour after dosing.

For a typical immediate-release tablet (not enteric-coated or extended-release), the general path in the body runs: disintegration → dissolution → absorption in the gut → rising blood concentration → effect. Roughly:

Stage	Approx. time after dosing
Tablet starts to disintegrate	5–15 min
Most of it has disintegrated/dissolved	15–30 min
Absorption is underway	20–40 min
Blood concentration starts rising clearly	30–60 min
A relatively clear effect appears	40–90 min
Blood concentration peaks	1–3 hours

The key distinction here is that “disintegration” and “absorption” aren’t the same thing. A tablet breaking into small particles doesn’t mean the active ingredient has already entered your bloodstream — it still has to dissolve and then get absorbed before blood levels actually rise.

Going by that general timeline, dosing 30–35 minutes before a session (as I did in session 2) may have landed a bit before the effect was expected to have kicked in. Moving to a 60-minute gap from session 3 onward likely meant I was running the first stage of the test with the effect already reasonably established.

So starting with session 3 (6 capsules), I extended the warm-up to 20 minutes (5-minute walk + 10 minutes at 8:03/mi, 5:00/km + 5 minutes at 7:15/mi, 4:30/km) and moved the test start to 60 minutes after dosing. The goal was to make sure enough time had passed before even the first stage of the test.

The clear shift in both perceived effort and the numbers started right after that change, from session 3 onward. But I can’t isolate, from this data alone, whether that shift came from the “6-capsule dose” or the “60-minute timing” — both changed at once.

I want to be upfront about that rather than conveniently crediting it all to dosage.

Also, the test period ran from July into August, and temperature and humidity crept up with each session. Even on an indoor treadmill, rising outdoor temperatures nudge the indoor temperature up too, so later sessions may have been running under slightly less favorable conditions.

Even accounting for that, the fact that both lactate and perceived effort came in lower on KATSUO STAMINA sessions is a result that’s hard to write off as coincidence.

One more limitation: I scored my perceived effort knowing which condition I was in each time. That means the belief that “KATSUO STAMINA should make this easier” could have influenced how I rated the effort. This wasn’t a blinded test where someone else controlled the conditions, and I want to flag that clearly.

And to be clear, this is data from one person. There’s no guarantee anyone else would get the same result under the same conditions.

A Possible Scientific Explanation (Still a Hypothesis)

As I covered in my product review, there’s a line of research suggesting the migratory fish powder activates a cell’s antioxidant system, which may in turn affect how lactate gets processed.

The pattern I observed here — a difference that only shows up in the pace range where lactate climbs fastest — doesn’t seem to contradict that hypothesis.

That said, this is only at the “consistent with the hypothesis” stage. This record alone doesn’t prove the mechanism.

What’s Next

Personally, I’m encouraged by what I’ve seen so far. But this is still just my own data, and I can’t tell readers that it “works” as a blanket statement. Please treat it as one data point to factor into your own decision, not a verdict.

A proper investigation would need larger-scale data collection, run with a sports science institution. Not many runners can repeat a controlled test like this on their own, but if this gives someone a useful starting point to try something similar, I’d be glad.

If You’re Curious About KATSUO STAMINA

Up to this point, I’ve shown you my own lactate data exactly as it is — the encouraging parts and the parts that are still unclear.

If you want to know more about the ingredients and the mechanism, I cover the manufacturer’s claims, the research background, and dosing in my KATSUO STAMINA product review.

Reading that alongside this article should make it clearer what context this data came from.

If you’re curious, here’s a link to the official site.