What is actually known, and what is only claimed

Men discuss a great many methods for improving sexual performance. Some have been studied properly. Some have been studied in a different population, for a different purpose, and then borrowed. Some have never been studied at all and circulate entirely on reported experience.

The Research Lab goes through them one at a time and says which is which.

This is not a set of instructions. These pages describe what a method involves so that you can recognize what is being discussed and understand the claims attached to it. They do not provide training protocols, repetitions, durations or progressions, and publishing one is not the purpose.

It is also not an endorsement. Describing a method accurately, including the reasons men are drawn to it, is a different act from recommending it. Where the honest answer is that nobody knows, these pages say nobody knows.

1. How we read the evidence

Every claim in the Lab carries one of four labels. The label is a shorthand for the kind of evidence behind a claim. It is not a score, it is not a rating, and it never appears without prose underneath it explaining what the evidence actually is and where it falls short.

That last point matters more than the labels themselves. A badge is easy to skim and easy to misread as a verdict. The reasoning beside it is the part that is true.

Supported by clinical evidence
Controlled studies in humans, published in peer-reviewed journals, that tested this intervention for this purpose and found an effect. The label says the evidence exists. It does not say the effect is large, that it applies to you, or that the studies were free of limitations, which is why the text beside it describes the actual findings.
Preliminary evidence
Published human research exists, and it is early: small samples, short follow-up, no control group, a single center, or results that have not been reproduced. Enough to take seriously as a question. Not enough to act on as a conclusion.
Community-reported, unverified
The claim comes from what men say about their own experience in forums and videos. These reports are real in the sense that people genuinely wrote them. They are unverified in every other sense: nobody measured anything, nobody tracked who stopped, and the men who had a bad outcome are not a group that posts as often as the men who had a good one.
Insufficient evidence
No published study has tested this claim, or the studies that exist cannot answer it. This label is not a verdict that the claim is false. It means the question is open and currently unanswerable from the literature.

2. What the Lab is trying to be

Curious. Methods that have not been studied are still worth understanding, because men are already doing them and deserve a straight account rather than silence.

Independent. The Blueprint sells a training app. That is a reason to be more careful here rather than less, so the Lab does not recommend our own product as the answer to questions the evidence has not settled, and these pages carry no sales offer.

Transparent. Sources are cited and linked. Where a source says something less convenient than the popular claim, the page says so. Where we could not find evidence either way, the page says that too, which is a more common outcome than you might expect.

Educational. The goal is that you finish a page understanding the subject well enough to judge the next claim you read about it on your own.

3. Topics

Manual techniquesDirectional pulls, the V-stretch, the wet jelq and the uli. What each one mechanically is, why men try them, what the literature does and does not establish, and the risks that follow from the mechanics.Insufficient evidence Reports vs. ResearchLarge communities, personal experiments and evidence checks: glans fullness, scrotal position and ejaculate-volume claims.Community-reported, unverified Performance nutritionBeetroot, leafy greens, watermelon and the nitric oxide pathway. What vascular studies show and what they do not prove.Supported by clinical evidence Supplement evidenceCitrulline, arginine, ginseng and semen-volume blends. What controlled human studies and safety advisories actually establish.Preliminary evidence

New investigations are added when claims and sources have been reviewed. Community membership is a measure of interest, not a count of verified outcomes.

4. Before you read further

Two things worth settling.

The first is that a method having no evidence behind it does not make it harmless, and a method having evidence behind it does not make it right for you. Those are separate questions and the Lab treats them separately.

The second is that most men who are worried about their penis have a normal one. The NHS puts it plainly, and so does Healthy Male, the Australian government funded men's health service: concern about size is common, and the size itself usually is not the problem. A systematic review of interventions in men complaining of small penis size found that counseling helped many of them accept that they were normal, which was more than most of the physical interventions achieved.

If what brought you here is distress rather than curiosity, that is worth taking to a clinician or a therapist, and it is a more promising path than anything described on these pages.

5. Related reading

The Learning CenterSix guides on erections, ejaculation timing, the pelvic floor and conditioning, each with a free exercise and cited sources. What should I work on?Five questions, answered privately, that point you at a starting point and two free things to try. Your answers stay in your browser.

Last reviewed: 29 October 2026 Reviewed by: The Blueprint editorial team. No clinician has reviewed these pages.

Medical note: This material is general educational information for adults. It does not diagnose or treat any condition, and nothing here is a recommendation to perform any technique. Pain, swelling, bruising, a change in shape or curvature, difficulty passing urine, or any new lump should be evaluated promptly by a qualified healthcare professional.