Can Carnosine and Tyrosine Improve Performance When You’re Already Fatigued?

Most sports supplements are tested under pretty clean conditions.

Athletes show up rested, take the supplement, warm up, perform a test, and researchers see whether performance improves.

That's useful, but it's not necessarily when performance matters most.

In the real world, the deciding sprint, hard climb, final interval, or critical decision often happens after you're already tired. At that point, maintaining physical output is only part of the challenge. You also need to stay focused and make good decisions while fatigue is working against you.

A new 2026 study published in Frontiers in Nutrition looked at an interesting combination for exactly that situation: L-carnosine and L-tyrosine.

Researchers tested the supplements individually and together in professional soccer players after high intensity exercise. The results were surprisingly large. The combination improved anaerobic power, sprint performance, agility, technical performance, and several measures of cognitive function compared with placebo. carnosine and taurine

There is a lot to like about this study.

There are also enough questions that I'm not ready to call carnosine plus tyrosine the next great performance stack.

TLDR: Carnosine Helped Physical Performance, Tyrosine Helped Cognition, and the Combination Did Both

This was a small acute study involving professional male soccer players, so the results need to be replicated. But the study design was strong enough and the results interesting enough to deserve attention.

• 24 professional male soccer players completed a randomized, double blind, placebo controlled crossover study.
• Athletes completed four conditions: L-carnosine, L-tyrosine, L-carnosine plus L-tyrosine, and placebo.
• Supplements were consumed 60 minutes before testing.
• L-carnosine was given at 6 mg/kg of body weight, while L-tyrosine was given at 150 mg/kg.
• Athletes first completed a 30 second all out Wingate test to create substantial fatigue before performing sprint, agility, passing, and cognitive tests.
• L-carnosine primarily improved anaerobic power, sprint performance, and agility.
• L-tyrosine had a stronger effect on reaction time, attention, and cognitive performance.
• The combination produced the largest overall effects, including approximately 17% greater peak power and 17% greater average power compared with placebo.
• Sprint and agility performance improved by roughly 7% to 13% with the combination.
• Perceived exertion was approximately 12.5% lower with the combination.
• Blood lactate was not significantly different between conditions.
• The results are promising, but the study involved only 24 men, tested a single acute dose, and used a laboratory fatigue protocol rather than an actual soccer match.

carnosine and taurine

This Study Wasn't Really About Performing While Fresh

This is probably my favorite part of the study.

The researchers weren't simply interested in whether a supplement could improve an isolated sprint.

They wanted to know what happened after athletes were fatigued.

That's particularly relevant in soccer, where an athlete may have to sprint, change direction, control the ball, recognize what is happening around them, and make a good decision late in a match when both physical and mental fatigue are accumulating.

The researchers tried to recreate some of that challenge in the laboratory.

Participants first completed a 30 second all out Wingate cycling test. After only two minutes of passive recovery, they moved into an Illinois Agility Test, 10 meter and 30 meter sprints, and a soccer specific passing task. Cognitive function was then evaluated using a computerized Stroop test. carnosine and taurine

That makes the study more interesting than simply asking whether someone can produce slightly more power when they're completely rested.

The question was whether supplementation could help preserve physical and mental performance when fatigue was already present.

The Study Design Was Pretty Good

Twenty four professional male soccer players between 18 and 30 years old participated. Their average age was about 24 years, and they had an average of approximately 13.5 years of playing experience. All competed in the third professional tier of Turkish soccer. carnosine and taurine

The study used a randomized, double blind, placebo controlled crossover design.

That means every athlete completed all four conditions:

L-carnosine.

L-tyrosine.

L-carnosine plus L-tyrosine.

Placebo.

Because every athlete received every treatment, each player essentially served as his own control. That's useful in sports nutrition research because individual performance differences can be enormous.

There was a 96 hour washout period between conditions, testing occurred at the same time of day, strenuous activity was restricted before testing, and the athletes followed standardized procedures for diet, sleep, and recovery. carnosine and taurine

Those are legitimate strengths.

Let's Talk About the Doses

This part of the study deserves some attention.

The athletes consumed their supplements 60 minutes before testing following a standardized breakfast.

L-carnosine was administered at 6 mg/kg of body weight.

L-tyrosine was administered at 150 mg/kg.

The combination group received both at those same doses. carnosine and taurine

For the average participant in this study, who weighed approximately 74 kg (163 pounds), that works out to roughly:

440 mg of L-carnosine

and

11 grams of L-tyrosine.

That tyrosine dose is substantial.

The carnosine dose is interesting for the opposite reason. It's relatively small compared with the gram level doses sometimes used in direct carnosine supplementation research.

That becomes important when we start thinking about mechanism.

Carnosine and Beta Alanine Aren't the Same Thing

Before going further, there's an important distinction to make.

Carnosine is a dipeptide made from beta alanine and histidine and is stored in relatively high concentrations in skeletal muscle.

One of its important functions during high intensity exercise is helping buffer hydrogen ions inside muscle cells. As hydrogen ions accumulate during intense glycolytic exercise, maintaining intracellular pH becomes increasingly difficult.

Carnosine contributes to that buffering system. carnosine and taurine

This is also why beta alanine is used as a sports supplement.

Beta alanine is the rate limiting precursor for muscle carnosine synthesis. Supplementing beta alanine over time can increase muscle carnosine concentrations, which can subsequently improve buffering capacity during high intensity exercise.

But that's a chronic strategy.

This study did something different.

Researchers gave athletes L-carnosine itself only 60 minutes before exercise.

That's worth emphasizing because we shouldn't automatically take everything we know about chronic beta alanine supplementation and assume it applies to a single acute dose of carnosine.

Carnosine Primarily Helped Physical Performance

The pattern in the results was pretty clean.

Carnosine seemed to have its biggest effect on the physical side of performance.

Peak Wingate power with placebo averaged 780 watts.

With L-carnosine, it increased to approximately 846 watts.

That's about an 8.4% improvement.

Average power increased from approximately 415 watts with placebo to 455 watts with carnosine, an improvement of about 9.6%. carnosine and taurine

Carnosine also significantly improved both 10 meter and 30 meter sprint performance compared with placebo and produced a faster Illinois Agility Test time. carnosine and taurine

Those are meaningful differences.

But things became considerably more interesting when researchers added tyrosine.

The Combination Produced a 17% Increase in Peak Power

Under placebo, average peak power was 780.3 watts.

With carnosine plus tyrosine, it increased to 915.8 watts.

That's approximately a 17.4% increase in peak power.

Average Wingate power increased from 415.3 watts to 485.3 watts, or roughly 16.9%. carnosine and taurine

Those are huge effects for an acute nutritional intervention.

And that's exactly why I think we should be interested while also remaining skeptical.

A 17% improvement in peak power isn't a tiny statistical difference that nobody would notice outside a laboratory. If an acute supplement combination consistently improved performance by that magnitude in trained athletes, it would be an extremely meaningful ergogenic aid.

The researchers also reported that the combination significantly outperformed tyrosine alone for several power outcomes. carnosine and taurine

So far, so good.

But the benefits weren't limited to a bike test.

They Were Faster After They Were Fatigued

Remember, the athletes completed their sprint and agility testing after the all out Wingate effort.

Under placebo, the 10 meter sprint took an average of 2.10 seconds.

With carnosine plus tyrosine, it dropped to 1.84 seconds.

For the 30 meter sprint, times decreased from 5.06 seconds with placebo to 4.40 seconds with the combination.

Illinois Agility Test performance improved from 17.25 seconds to 16.05 seconds. carnosine and taurine

The researchers summarized the sprint and agility improvements with combined supplementation as roughly 7% to 13% compared with placebo. carnosine and taurine

Again, these aren't trivial differences.

In a sport where fractions of a second can determine whether you reach a ball before an opponent, improvements of that magnitude would matter.

Tyrosine Became More Interesting Once the Brain Was Tested

Tyrosine didn't produce the same physical effects as carnosine.

Its more interesting effects appeared on the cognitive side.

Tyrosine is an amino acid that acts as a precursor for catecholamines including dopamine, norepinephrine, and epinephrine.

Under conditions of high stress and fatigue, maintaining catecholamine availability may help support attention, reaction time, decision making, and cognitive control. carnosine and taurine

That's why tyrosine research tends to become more interesting under stressful conditions.

If you're sitting comfortably at a desk after a good night's sleep, additional tyrosine may not accomplish much.

If you're physically exhausted, mentally stressed, sleep deprived, cold, hot, or otherwise operating under substantial physiological stress, the story may be different.

This study intentionally tested cognition after physical fatigue had already been created.

That's exactly where tyrosine should theoretically have the best chance of helping.

Reaction Time Improved Substantially

The researchers used a Stroop test with neutral, congruent, and incongruent conditions.

The incongruent condition is the hardest because the athlete has to suppress an automatic response and correctly respond to conflicting information.

Under placebo, average incongruent reaction time was approximately 965 milliseconds.

With tyrosine alone, it fell to approximately 790 milliseconds.

With carnosine plus tyrosine, it dropped further to approximately 720 milliseconds. carnosine and taurine

The combination was significantly faster than placebo, carnosine alone, and tyrosine alone on this demanding cognitive task. carnosine and taurine

Error rates also decreased.

That matters because improving reaction speed isn't particularly useful if someone simply starts responding faster and making more mistakes.

Here, the combination generally produced faster responses and fewer errors.

Carnosine Alone Didn't Do Much for Cognition

This is another result I like because it makes the findings somewhat more biologically coherent.

Carnosine alone improved physical outcomes but did not significantly differ from placebo on the cognitive outcomes.

Tyrosine, on the other hand, improved reaction time and error rates.

The combination did both. carnosine and taurine

That's essentially the hypothesis behind combining the two ingredients.

Carnosine potentially addresses peripheral muscular fatigue.

Tyrosine potentially addresses central cognitive fatigue.

Put them together and, theoretically, you're attacking two different performance limitations at the same time.

The researchers describe this as a potentially synergistic relationship.

I'd be a little more conservative.

The results are consistent with complementary effects. One small study isn't enough to prove true physiological synergy.

That's an important distinction.

Passing Performance Improved Too

The researchers also created a soccer specific passing test.

Players stood in the middle of a circle surrounded by numbered targets and had to complete a sequence of 20 passes as quickly and accurately as possible.

After the fatiguing Wingate protocol, average completion time under placebo was 29.51 seconds.

Carnosine improved it to 27.10 seconds.

Tyrosine improved it to 26.17 seconds.

The combination produced the best result at 24.33 seconds. carnosine and taurine

The researchers calculated the combined improvement at approximately 17% compared with placebo. carnosine and taurine

That's interesting because passing requires more than raw muscular power.

The athlete has to process the sequence, orient himself correctly, control the movement, and execute accurately while tired.

That makes it a useful attempt to bridge the gap between a laboratory performance test and an actual sport skill.

There is one pretty important limitation, though, which we'll get to shortly.

The Workout Felt Easier Too

Perceived exertion after the Wingate test averaged 18.4 with placebo.

With the combination, it fell to 16.1, approximately a 12.5% reduction. carnosine and taurine

That's interesting because the athletes weren't performing less work.

They were generally performing better.

Producing more power while perceiving the effort as somewhat lower could potentially matter during repeated high intensity competition.

But there's another result here that prevents us from telling too neat of a physiological story.

Lactate Didn't Significantly Change

Blood lactate averaged:

10.75 mmol/L with placebo

and

8.00 mmol/L with carnosine plus tyrosine.

Numerically, that's a decent difference.

Statistically, however, blood lactate did not significantly differ between conditions (p = 0.109). carnosine and taurine

The researchers discuss the lower numerical lactate concentration as potentially reflecting better management of exercise induced acidosis, but the statistical result doesn't establish that.

So I wouldn't use this study to claim that carnosine plus tyrosine "reduces lactate."

It didn't demonstrate that.

And lactate itself isn't simply a waste product responsible for fatigue anyway.

Here's Where I Start Asking Questions

These results are impressive.

Maybe a little too impressive.

An acute supplement intervention producing approximately 17% greater peak power, 17% greater average power, double digit improvements in sprint performance, substantially faster cognitive responses, fewer cognitive errors, and better sport specific performance deserves replication.

That's not an accusation that anything is wrong with the study.

It's simply how science should work.

Extraordinary performance improvements from a relatively simple nutritional intervention should make us interested enough to run another study, not confident enough to immediately treat the effect size as established.

There are also some important limitations in the experiment itself.

Only 24 Athletes Participated

The crossover design helps considerably because every participant experienced every condition.

The researchers also performed an a priori power calculation suggesting they needed at least 22 participants, and all 24 athletes completed the experiment.

So the sample wasn't arbitrarily chosen. carnosine and taurine

Still, it's 24 people.

All were young male professional soccer players competing in the same Turkish league.

We don't know whether women would respond similarly.

We don't know whether recreational athletes would.

We don't know whether endurance athletes would.

And we certainly don't know whether a 45 year old cyclist or runner should expect anything resembling a 17% improvement in performance.

This study tells us what happened in these 24 athletes under this particular protocol.

That's where the conclusion should start.

This Was Acute Supplementation

The researchers only examined the effects of a single acute dose.

That means we don't know whether repeated use would maintain the same benefits, produce tolerance, change the response, or introduce issues that weren't apparent after one exposure.

The authors specifically state that long term safety of the combined supplementation was not assessed and that future studies need to examine chronic supplementation protocols.

That's particularly relevant because the tyrosine dose was substantial.

For a 74 kg athlete, 150 mg/kg is roughly 11 grams of tyrosine at once.

That's not the kind of dose I'd casually extrapolate into a recommendation for people to start taking every day based on one 24 person study.

The Carnosine Dose Raises Questions Too

This is probably the part of the paper I'd most like to see replicated.

At 6 mg/kg, the average participant received only around 440 mg of L-carnosine.

The authors attribute the physical performance improvements primarily to carnosine's role in intramuscular pH buffering. carnosine and taurine

The challenge is that orally consumed carnosine is rapidly broken down in circulation by the enzyme carnosinase. The authors themselves acknowledge its relatively short lived presence when explaining why their 96 hour washout period was sufficient. carnosine and taurine

That doesn't prove the proposed mechanism is wrong.

But it does make an acute ~440 mg dose producing an 8% to 10% improvement in power on its own something I'd want independently replicated before building a strong supplementation recommendation around it.

This is one of those cases where the result is interesting enough to pay attention to precisely because it raises another question.

This Wasn't an Actual Soccer Match

The researchers did a reasonable job trying to create fatigue and then assess sport relevant performance.

But a Wingate test followed by sprints, an agility course, passing, and a Stroop test isn't a soccer match.

Real competition includes opponents, tactical decisions, emotional stress, unpredictable movement, collisions, changing intensities, environmental conditions, and 90 minutes of accumulated fatigue.

The authors acknowledge this directly.

The laboratory setup can't reproduce the full psychological and tactical complexity of competition.

So we can say the combination improved laboratory and field test performance under experimentally induced fatigue.

We can't say it makes someone a better soccer player.

There's Another Limitation Hidden in the Passing Test

The passing test sounds sport specific, and it is.

But it was developed by the researchers for this experiment.

Although its design was based on previously validated soccer passing assessments, the authors acknowledge that its own test retest reliability and construct validity haven't been formally established.

That means I'd put considerably more confidence in the Wingate, sprint, agility, and Stroop results than in the precise magnitude of the passing result.

The reported 17% improvement in passing performance is interesting.

I wouldn't build the headline around it.

They Also Didn't Collect Baseline Measurements Before Every Condition

The crossover design helps control for individual differences, and condition order was randomized.

However, researchers did not collect a separate baseline performance measurement before each experimental visit.

The authors identify this as a limitation because it prevents direct comparison of precondition performance between visits.

They also note that although treatment order was randomized, potential visit or order effects weren't statistically evaluated.

Again, none of this invalidates the study.

It simply adds context to some very large reported effects.

So Is This Really "Synergy"?

Maybe.

But I'd hold off on that word.

The study clearly showed that the combination generally produced better outcomes than either ingredient alone.

That's important.

Carnosine appeared stronger for physical performance.

Tyrosine appeared stronger for cognitive performance.

The combination improved both.

That is exactly what we'd expect if the ingredients were affecting complementary systems.

But demonstrating that two ingredients work well together isn't necessarily the same as proving biochemical synergy.

I'd call this a promising combination with complementary effects until we have more research.

That may be less exciting marketing copy.

It's also more accurate.

The Bigger Idea Here Is More Interesting Than Either Ingredient

What I find most interesting about this study isn't necessarily carnosine or tyrosine.

It's the idea behind the combination.

Most sports supplements are designed around improving a single output.

More power.

More endurance.

More blood flow.

More focus.

But athletes rarely fail because of only one physiological limitation.

Late in competition, you're dealing with muscular fatigue, metabolic stress, declining attention, slower reaction time, reduced motivation, and poorer decision making simultaneously.

A supplement strategy that targets both physical and cognitive fatigue makes considerably more sense than simply adding another stimulant.

That's especially relevant in sports such as soccer, basketball, hockey, cycling, trail running, obstacle racing, and other events where athletes need to continue making decisions while physically exhausted.

Whether carnosine plus tyrosine ultimately turns out to be the best way to accomplish that remains an open question.

But the concept is good.

What I Would Actually Do With These Results

I wouldn't immediately start recommending 150 mg/kg of tyrosine plus 6 mg/kg of carnosine before every workout.

The study isn't strong enough for that yet.

For tyrosine, the results add to an existing rationale for using the amino acid when cognitive performance needs to be maintained under significant physiological stress.

For carnosine, I'm more cautious about interpreting such large acute effects until another research group reproduces them.

And for the combination, I'd call the findings very promising but preliminary.

That's essentially where the researchers land as well. They specifically state that the findings are based on acute responses in a small, male only sample and should be confirmed in larger and more diverse groups before firm recommendations are made.

That's a reasonable conclusion.

The Bottom Line

A new 2026 randomized, double blind, placebo controlled crossover study tested L-carnosine, L-tyrosine, and their combination in 24 professional male soccer players performing under fatigue. carnosine and taurine

Carnosine primarily improved physical performance.

Tyrosine primarily improved cognitive performance.

Combining them produced the largest overall effects.

Compared with placebo, the combination increased peak power by approximately 17%, average power by approximately 17%, improved sprint and agility performance by roughly 7% to 13%, reduced perceived exertion by about 12.5%, and improved several measures of reaction time and cognitive accuracy.

That's impressive.

It's also one small study.

The participants were all young professional male soccer players, supplementation was acute, the experiment didn't reproduce an actual match, long term safety wasn't assessed, and some of the reported performance effects were large enough that I'd really like to see them independently replicated.

So I'm not ready to tell athletes that carnosine plus tyrosine is some new secret performance combination.

But I'm definitely interested.

More importantly, I think the study highlights an area of sports nutrition that deserves more attention: maintaining the brain and the body at the same time when fatigue starts piling up.

Being powerful when you're fresh is useful.

Being powerful, focused, and capable of making good decisions when everyone else is tired may be considerably more important.

Reference:

Bilgin S, Bozyılan E, Buzdağlı Y, Karaç Öcal Y, Gürkan O, Toktaş S, İnan H, Egil İ, Yarayan YE. Combined L-carnosine and L-tyrosine supplementation as an ergogenic strategy for physical and cognitive performance under fatigue in professional football players. Frontiers in Nutrition. 2026;13:1868802. Published August 17, 2026. doi:10.3389/fnut.2026.1868802.