KATSUO STAMINA Reviewed: Science, Studies & My Lactate Data

This article breaks down KATSUO STAMINA’s ingredients, dosing, and the manufacturer’s own trial data in plain language. I’ll also cover the science behind its migratory fish powder and publish my own lactate test data.

What Is KATSUO STAMINA? Product Overview

Item	Details
Seller	Stamina Sports Co., Ltd.
Price	¥1,398 (tax included) / pack
Contents	8 capsules (1.6g) / pack (nutrition facts are based on a 4-capsule serving)
Main ingredient	Migratory fish powder
Manufacturing	GMP-certified factory in Japan
Customer reviews	4.8/5 (58 reviews, as of August 2026)

KATSUO STAMINA’s main ingredient is a peptide found in bonito and other migratory fish. According to the manufacturer, a small amount of salmon is also used to ensure a stable supply of raw material.

The manufacturer describes the product as containing “the equivalent of 1.5kg of bonito.” This is a raw-material framing — it refers to how much bonito goes into making the product, not a claim about the effect of the ingredient itself.

Dosage depends on your event and distance. According to the official site’s dosage guide, here’s what they recommend:

Event	Dosage
Half marathon	4 capsules (30 min before start)
Full marathon	8 capsules (30 min before start)
Ultramarathon	8 capsules (30 min before start) + 4 capsules every 20km
Trail (under 15km)	4 capsules (30 min before start)
Trail (15–30km)	8 capsules (30 min before start)
Trail (30km+)	8 capsules (30 min before start) + 4 capsules every 15km or 1,000m of elevation gain

For a recreational runner training for a full marathon, the standard reference point is 8 capsules taken 30 minutes before the start.

The product is manufactured at a GMP-certified factory in Japan. GMP (Good Manufacturing Practice) is a set of standards for ensuring quality and safety in the production of pharmaceuticals and health foods.

KATSUO STAMINA is reportedly used by several elite athletes, including the winner of the 2024 Trans Japan Alps Race and a 2025 Olympic competitor. Customer reviews on the official store also run high, at 4.8/5 across 58 reviews.

The Manufacturer’s Two Key Claims

According to information published by the manufacturer, KATSUO STAMINA’s effects come mainly from two mechanisms.

Claim 1: Faster Lactate-to-Energy Conversion

The first is speeding up the conversion of lactate — the byproduct your body can’t fully process during hard efforts — into usable energy.

The glycolytic system (the pathway that produces energy quickly without oxygen) yields roughly 2 ATP per mol of glucose. ATP is the basic unit of energy your cells run on. The pathway that converts lactate to energy using oxygen produces roughly 30 ATP — about 15 times more.

Those numbers are biochemically accurate, and the existence of this pathway itself is well established in other research.

This “lactate-to-energy” capacity is also a key factor when thinking about lactate threshold.

Claim 2: Reduced Creatine Kinase (CK) Spike

The second claim is that it suppresses the rise in blood creatine kinase (CK) — a marker of muscle damage — supporting reduced muscle damage and faster recovery.

The manufacturer ran its own placebo-controlled trial with 18 participants and reports that the group taking KATSUO STAMINA showed a smaller post-exercise rise in CK.

The official site also mentions support for reducing exercise-induced muscle cramps.

A Third Claim From Their Materials: Extended Fat Utilization

Materials shared with me as part of this partnership also described a third mechanism: extending the time your body relies on fat for fuel, which in turn is said to shift lactate threshold toward higher intensities.

Carbohydrates yield about 38 ATP per mol, while fatty acids yield about 129 ATP per mol — roughly 3.4 times more energy. That figure itself is biochemically accurate.

If you’re curious, you can check the current price on the official site below.

Dosage, Timing, and Safety

Dosage varies by event and distance, as shown in the spec table above. It’s not designed for continuous, daily use — it’s marketed as a supplement you take around a race or a specific hard session.

Manufacturing takes place at a GMP-certified domestic factory, which gives some baseline assurance on quality control. Since the raw material is a fish-derived food ingredient, it’s relatively low-risk to try from a safety standpoint.

I Dug Into the Science Behind the Migratory Fish Powder

What Is a Migratory Fish Powder?

KATSUO STAMINA’s main ingredient is a small protein fragment (peptide) found abundantly in the muscle tissue of bonito and other migratory fish. It’s been consumed as a food ingredient for a long time.

If you want to dig deeper into how lactate itself is metabolized, I’ve covered that in detail in a separate article on lactate metabolism.

Why Is It Said to Affect Lactate?

I dug into the literature to understand why this ingredient is linked to lactate at all. A 2023 study found, at the molecular level, that this compound activates a cell’s antioxidant system through the Nrf2 pathway※1.

When the antioxidant system activates, it helps clear reactive oxygen species — unstable molecules produced during exercise that can damage cells. Stitching several studies together, that clearance process may in turn affect the enzymes responsible for processing lactate.

That said, these findings come from separate studies stitched together. No study has yet directly shown that taking the migratory fish powder alone lowers lactate levels in humans.

What the Sprint and High-Intensity Studies Show

There’s also research on high-intensity exercise. Studies on repeated sprints and power output have reported performance improvements in groups that took this compound※2※3.

However, these studies had participants take the migratory fish powder combined with another compound from the same family. Whether KATSUO STAMINA reproduces that exact combination isn’t clear.

Can a Single Dose Really Work?

The manufacturer says taking it on the day of exercise is effective, but there are a few things worth looking at carefully.

First, while the lactate-to-energy pathway itself is confirmed to exist in other research, there’s no evidence yet that taking KATSUO STAMINA directly strengthens that pathway in the human body.

The manufacturer’s own CK trial — while structurally reasonable, with a placebo group and a dose-response comparison — hasn’t been peer-reviewed, and each group had only 6 participants. It’s best treated as reference-level evidence rather than proof.

The other claim — extended fat utilization — assumes an adaptation driven by changes in gene expression. That kind of adaptation typically takes days to weeks to develop, so it’s not yet clear whether this pathway can be triggered by a single dose.

It’s also worth keeping in mind that the research conditions (dosage, compound combinations) don’t necessarily match KATSUO STAMINA exactly.

I Ran My Own Treadmill Lactate Test

Rather than relying only on published studies, I wanted to check this on my own body. I ran an incremental exercise test on a treadmill, comparing my lactate levels with and without KATSUO STAMINA.

In some sessions, I saw a difference in lactate at the higher-intensity stages. Here’s how the condition averages compared:

This is my own personal record, and I wasn’t able to control every variable perfectly. For the full data and how to interpret it, I’ve published everything in a companion article: I Self-Tested My Lactate With and Without KATSUO STAMINA.

Who This Supplement Might Suit

I think KATSUO STAMINA is best suited for runners who regularly do high-intensity training — interval sessions, reps — and are chasing a personal best through hard, structured work.

The lactate metabolism pathway this ingredient is said to act on assumes you’re already producing a meaningful amount of lactate. Runners doing more high-intensity work generate more lactate day to day, so I’d expect them to notice more of a benefit.

On the flip side, I want to be honest here too: if your training is mostly easy jogging and very slow long runs, you’re simply not producing much lactate to begin with, so you may not notice much of an effect from KATSUO STAMINA.

The same is likely true if your carbohydrate intake tends to run low, since that also suppresses lactate production.

To be clear, this is my own interpretation, not an established scientific standard. But based on the mechanism, I think it’s a reasonable expectation.

Summary

Honestly, I’d been avoiding KATSUO STAMINA out of a bias. I genuinely didn’t believe a few capsules could meaningfully change how your body handles speed endurance.

But after testing it on myself and seeing the actual numbers, I think that assumption is worth reconsidering. To be clear, this is a single data set from one person — it doesn’t prove anything conclusively.

Still, at the very least, my earlier “not worth trying” attitude wasn’t a fair one.

KATSUO STAMINA isn’t designed for continuous use — it’s meant to be taken on a specific day, like race day, rather than as part of a long-term training buildup. That makes the barrier to trying it fairly low.

If you’re curious, trying it a few times and looking at your own data is a reasonable way to decide for yourself.

Where to Buy

KATSUO STAMINA is available through the official site as well as Amazon. We’ve set up a dedicated purchase link for Running Scientist readers on the official site below.

References

※1 Chen M, et al. The Preventive Mechanism of Anserine on Tert-Butyl Hydroperoxide-Induced Liver Injury in L-02 Cells via Regulating the Keap1-Nrf2 and JNK-Caspase-3 Signaling Pathways. Marine Drugs. 2023.

※2 Blancquaert L, et al. Acute preexercise supplementation of combined carnosine and anserine enhances initial maximal power of Wingate tests in humans. J Appl Physiol. 2021;130(5):1334-1344.

※3 de Jager S, et al. The ergogenic effect of acute carnosine and anserine supplementation: dosing, timing, and underlying mechanism. J Int Soc Sports Nutr. 2022;19(1):70-91.