Hair and sport: the complete protocol

You wash your hair five times a week, sometimes six, and you wonder when it is going to show. You retighten your ponytail in the second set. You leave the changing room with your hair wet and tied up. On Wednesdays you come out of the pool with lengths like straw. Here is what research establishes on each of those points, and the steps to apply before, during and after your session. They are free.

What really damages your hair when you train

Let us start with sweat, since sweat is what gets blamed. It is essentially slightly acidic salt water (sodium and chloride from 10 to 90 mmol/L), saltier when you sweat hard (Baker and Wolfe, 2020). No indexed publication demonstrates that it degrades the hair fibre: the subject has not been studied. Absence of data is not proof of harmlessness, nobody has measured it, that is all.

What is documented in athletes concerns the scalp and the nape, not the fibre. Acne mechanica is described as a folliculitis triggered by heat, sweating, pressure, occlusion and repeated rubbing. The only prevalence figure available covers 453 helmeted American football players, all male, and concerns acne keloidalis nuchae: 15.5% in high-school players versus 1.2% in older players (Knable et al., 1997). The mechanism transfers to a headband or a helmet strap, the figure does not, and these conditions are a matter for medical advice; none of our products acts on them. In other words, what matters here is not the sweat, it is the soaked headband kept on for an hour after training.

The real mechanical risk is called traction alopecia. It comes from hairstyles that pull, and it rises with the intensity and above all the duration of traction repeated in the same spot. At a late stage it becomes scarring and irreversible if the practices do not change (Billero and Miteva, 2018). It is styling practices that are at fault, not hair type.

The pool, for its part, acts in two ways at once. Among 67 swimmers from the Japanese national team, 61% showed discolouration, against 0% in 54 age-matched controls. In a subgroup of eight swimmers examined by electron microscopy, the golden hairs showed complete loss of the cuticle, and all discoloured hairs had a lower sulfur content than the controls. The damage comes first from water friction on the fibre, after which hypochlorous acid can penetrate as far as the cortex and oxidise the melanosomes there (Nanko et al., 2000). A recent review also describes melanin degradation and damage to keratin integrity attributed to chlorine (Cedirian et al., 2025). Green tints on light hair, on the other hand, come from copper dissolved in the water, not from chlorine: chlorinated water with no copper in it does not turn hair green (Bhat et al., 1979).

The protocol, session by session

Everything that follows is free. The strongest data concerns practices, not products.

In the gym or running

1. Loosen it by one notch and move the anchor point from one session to the next. The American Academy of Dermatology (AAD) recommends alternating hairstyles.
2. If it pulls, if it stings, if it hurts, take it down immediately. The AAD puts it this way: a painful hairstyle is too tight. It lists separately tingling, crusting and peeling of the scalp, which are warning signs to watch for.
3. Outdoors, wear a cap or a wide-brimmed hat, and avoid the 10 am to 2 pm window. UVB degrades hair protein 2 to 5 times more than UVA combined with visible light, with the cuticle affected first (Nogueira and Joekes, 2004; Lee, 2009).
4. After training, take off the headband and helmet, air them out, clean the inner foam. Do not keep them on for another hour.
5. Wash as often as your scalp asks for it. In the only interventional trial available, run with a different shampoo on a population with no scalp condition, daily washing was better tolerated than weekly washing (Punyani et al., 2021). That result concerns wash frequency, not our formulas. On our product pages you will read a benchmark of 2 to 3 washes a week: that is a benchmark for comfort and for making the product last, not a safety limit.
6. Shampoo on the scalp, conditioner on the lengths. Not scrubbing the ends reduces friction and tangling (Dias, 2015).
7. Blot with a towel instead of rubbing, and only tie your hair up once the lengths have stopped dripping. It is friction that lifts the cuticle (Dias, 2015), and wet combing increases long-segment breaks (Robbins and Kamath, 2007). If you have to leave with damp hair, a clip or a loose plait is better than a tight band.
8. Detangle with a conditioner, from the ends up to the roots, never by pulling on wet hair gathered into a tight ponytail.
9. Between two sessions, a rinse with clean water is enough. It is a question of comfort and smell, not of rescuing your hair.

At the pool

1. Wet your hair with fresh water in the shower before getting into the pool. A fibre saturated with fresh water takes up less chlorinated water. This is an expert recommendation based on a plausible mechanism, not a controlled trial: nobody has measured how much chlorine is avoided, so no percentage is given here.
2. Put an oil or a leave-in conditioner on the lengths before the cap. The AAD names those two products precisely, because the barrier you want is an oily one. A water-based leave-in does not do that job.
3. A well-fitted cap, with the hair gathered underneath without pulling. What the cap really does: it reduces contact with the water, it does not remove it, and no study quantifies how effective it is (there is no verifiable source behind the 70 to 80% protection you read online). A tight tie under the cap combines tension and friction.
4. Rinse with clean water as soon as you leave the pool, then wash, then apply a conditioning treatment. That is the sequence recommended by the AAD.
5. Green tints: look at the copper in the water, not at the chlorine. The answer is an occasional chelating shampoo. Our formulas contain none and do not remove bound copper.

The mistakes that cost the most

The mistake	What to do instead	Why
Spacing out shampoos so as not to damage your hair	Wash as often as your scalp asks for it, with a conditioner at every wash	In the only interventional trial available, run with a different shampoo on a population with no scalp condition, daily washing was better tolerated than weekly washing (Punyani et al., 2021)
Pulling it tight until nothing moves, always in the same spot	Loosen it, change the height of the tie, alternate flat plaits and loose hair	Traction risk rises with intensity and duration (Billero and Miteva, 2018)
Jumping into the pool with dry hair	Fresh-water shower, oil or oily leave-in on the lengths, well-fitted cap	A set of steps recommended by the AAD
Tying wet hair up tightly	Detangle with a conditioner, let it stop dripping, then tie it loosely	Wet combing increases long-segment breaks (Robbins and Kamath, 2007); as for tight ties on wet hair, no study exists, it is the combination of tension and fragility that calls for caution
Keeping your headband and helmet on after training	Take them off, air them out, clean the foam	Heat, occlusion and rubbing, described factors in acne mechanica (Knable et al., 1997)

What we sell, and what it is for

Two packs depending on how you train, never a single product.

If you train in the gym or run, the Volume Duo (/RESET Shampoo and /RESTORE Conditioner) is the only thing you need. Not one product on its own, because the literature describes two complementary steps here: shampoo on the scalp, conditioner on the lengths, the latter lubricating the cuticle and reducing friction (Dias, 2015). Worth knowing before you click: these two formulas contain menthol and camphor, they are not suitable for young children, and the Conditioner contains sweet almond oil.

If you swim several times a week, the Complete Collection adds the /REPAIR Repair Mask and the /REVEAL Shine Mist. With one reservation that works against us: for the pre-pool step, the AAD talks about an oil or a leave-in conditioner, because the barrier you want is an oily one. Our /REVEAL Mist is a water-based leave-in, with no oily phase: it deposits keratin on the fibre, it does not act as a barrier against chlorine, and for that step you need an oil. What genuinely helps a swimmer in this pack is the after-swim step, the /REPAIR Mask. "Repair" there is a product name, not a promise: it deposits a film that softens hair and makes detangling easier, it rebuilds nothing and does not restore oxidised disulfide bonds. The AAD recommends practices, never a brand: no learned society recommends our products. Also worth reading before you click: this pack contains the Mask, so hydrolysed wheat protein and sweet almond oil, as well as the Shampoo and the Conditioner with their menthol. It therefore carries no "gluten-free" or "nut-free" claim.

The Shampoo is a plant-derived cleansing base, certified COSMOS NATURAL by Ecocert Greenlife, 99% natural origin according to the standard. What we will not write: "sulfate-free". It contains Sodium Coco-Sulfate, which is a sulfate, accepted by the COSMOS standard, which allows sulfated surfactants until 1 January 2029 (details in our guide to reading labels).

On keratin, here is the exact state of the evidence. The work available covers the ingredient, not our formulas. In the reference study, carried out on relaxed afro hair, low and medium molecular weight hydrolysed keratin peptides penetrate as far as the cortex, and it is the medium and high molecular weight ones that increase Young's modulus and reduce breakage (Malinauskyte et al., 2021). We do not know the molecular weight of the keratin in our formulas, so we cannot promise you that this result applies to them in the same way. A second study, on wool keratin proteins and peptides, the same raw material as ours, found improved properties on chemically treated hair (Barba et al., 2010); it does not test our formulas, and neither of the two measures how the effect holds up over several washes. In practice: the expected effect is a surface effect, it varies from one person to another depending on the condition of the hair, and it fades over successive washes.

Free delivery on orders over 49 euros.

What these products do not do

• They do not repair the fibre. Hair is a dead tissue, damaged keratin is not restored, and torn-off cuticle scales do not grow back (Dias, 2015).
• They do not remove bound chlorine or deposited copper: none of our formulas contains a chelating agent.
• The /REVEAL Mist does not act as a barrier against chlorine before the pool: it is a water-based leave-in, with no oily phase.
• They replace none of the free steps described above.
• They have no effect on hair loss, density or regrowth.
• They treat no scalp condition: not folliculitis, not acne keloidalis nuchae, not seborrhoeic dermatitis, not stubborn dandruff.
• Their effect does not last. It is renewed with each use and fades over successive washes.

What you should know before buying

Our products are not vegan. Their hydrolysed keratin is of animal origin: it comes from sheep's wool, an origin confirmed in writing by our manufacturer, who is the responsible person for the product under the European regulation. What we can set against that as a verifiable rule is the COSMOS standard, which certifies all four formulas and prohibits raw materials taken from live or slaughtered animals (points 6.1.3 and 6.1.4 of version 4.2). We give you the origin and the rule, you decide. Why "plant keratin" does not exist: it is explained here.

Allergens to know about. The Repair Mask contains hydrolysed wheat protein and sweet almond oil: if you are allergic to wheat or to tree nuts, do not use it. The Complete Collection contains that mask, so it carries no "gluten-free" or "nut-free" claim. The Conditioner in the Volume Duo also contains sweet almond oil. The Shampoo and the Conditioner contain menthol and camphor, hence the cooling sensation: they are not suitable for young children, in line with the manufacturer's instructions for use. On a sensitive scalp, that cooling effect can cause slight tingling; on an irritated or broken scalp, do not apply and seek advice. Pregnant or breastfeeding: the Shampoo and the Conditioner contain rosemary and peppermint essential oils, so as a precaution ask a healthcare professional for advice. All four formulas are fragranced and contain fragrance components that must be declared, listed in full at the end of the INCI list. If you have a known allergy, read the full list and ask your doctor for advice.

Who they are not for. Not for a vegan. Not for anyone allergic to wheat or to tree nuts, as far as the mask and the packs containing it are concerned. Not for a scalp that is broken, flaring or sunburnt: do not apply, seek advice. And not for anyone looking for a treatment: unusual hair loss, a receding hairline, a widening parting, thinning patches at the temples, crusting or scalp pain are matters for a doctor or a dermatologist, whose job it is to decide which tests are useful.

Frequently asked questions

Do you have to wash your hair after every session?

Not necessarily. No publication demonstrates that sweat damages the fibre, as the subject has not been studied. Wash if comfort or smell call for it, and if that turns out to be every day, the available data shows no damage. Otherwise, a rinse with clean water is enough.

Does washing daily damage your hair?

The available data says the opposite: it was better tolerated than weekly washing on flaking, itching, smell and oxidative stress markers, with no damage to hair integrity (Punyani et al., 2021). Reservation: an Asian population with no scalp condition, using a shampoo other than ours.

Does sweating make your hair fall out?

Nothing demonstrates that. What is documented in athletes concerns the scalp and the skin, not the keratin. Unusual or persistent hair loss is a matter for medical advice.

Why do I have short broken hairs on the top of my head?

Several causes are possible and a sales page cannot settle it: normal regrowth, breakage from heat or brushing, or repeated traction. The early sign of traction described by the AAD is seen on the frontal hairline and the temples rather than on the top of the head. In every case, loosen your hair and change the height of your tie. If your hairline is receding, your parting is widening or you have pain, see a dermatologist: at a late stage, traction alopecia becomes irreversible.

Is a swimming cap enough?

No. It reduces contact with the water without removing it, and no published study measures how effective it is. It goes together with wetting your hair with fresh water, an oil or an oily leave-in on the lengths, and an immediate rinse.

Why does my blonde hair turn green after the pool?

Because of the copper dissolved in the water, not the chlorine. The answer is an occasional chelating shampoo: our formulas contain none.

Is the KERA NEXT shampoo sulfate-free?

No. It contains Sodium Coco-Sulfate, a sulfate accepted by the COSMOS standard, which allows sulfated surfactants until 1 January 2029. We will never write "sulfate-free", it would be false. What we can say: a plant-derived cleansing base, accepted by the COSMOS standard and certified by an independent body.

How long does the effect of a keratin treatment last?

As long as the deposit stays on the fibre, and no figure in days is verifiable: the available work on the ingredient does not measure how the effect holds up over several washes (Malinauskyte et al., 2021). It is upkeep to be repeated, not a repair.

Do you need a conditioner at every wash, even a daily one?

Yes. It lubricates the fibre and reduces friction, which is what hair that is tied up and washed often needs (our four-step routine).

Sources

• Nanko H, Mutoh Y, Atsumi R et al. Hair-discoloration of Japanese elite swimmers. The Journal of Dermatology, 2000. PMID 11092265.
• Cedirian S, Prudkin L, Piraccini BM et al. The exposome impact on hair health, Part I. An Bras Dermatol, 2025;100(1):131-140.
• Bhat GR, Lukenbach ER, Kennedy RR, Parreira RM. The green hair problem. Journal of the Society of Cosmetic Chemists, 1979;30:1-8.
• Nogueira ACS, Joekes I. Hair color changes and protein damage caused by ultraviolet radiation. J Photochem Photobiol B, 2004;74(2-3):109-117.
• Lee WS. Photoaggravation of hair aging. International Journal of Trichology, 2009;1(2):94-99.
• Baker LB, Wolfe AS. Physiological mechanisms determining eccrine sweat composition. Eur J Appl Physiol, 2020;120:719-752.
• Knable AL Jr, Hanke CW, Gonin R. Prevalence of acne keloidalis nuchae in football players. J Am Acad Dermatol, 1997;37(4):570-574.
• Punyani S, Tosti A, Hordinsky M, Yeomans D, Schwartz J. The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions. Skin Appendage Disorders, 2021;7(3):183-193.
• Dias MFRG. Hair Cosmetics: An Overview. International Journal of Trichology, 2015;7(1):2-15.
• Billero V, Miteva M. Traction alopecia: the root of the problem. Clin Cosmet Investig Dermatol, 2018;11:149-159.
• Robbins C, Kamath Y. Hair breakage during combing III. Journal of Cosmetic Science, 2007. PMID 17728947.
• Malinauskyte E, Shrestha R, Cornwell PA et al. Penetration of different molecular weight hydrolysed keratins into hair fibres. Int J Cosmet Sci, 2021;43(1):26-37.
• Barba C, Scott S, Roddick-Lanzilotta A, Kelly R, Manich AM, Parra JL, Coderch L. Restoring important hair properties with wool keratin proteins and peptides. Fibers and Polymers, 2010;11(7):1055-1061.
• American Academy of Dermatology, aad.org: Must-try summer hair care; Hairstyles that pull can lead to hair loss; Draelos ZD, Dermatologists' top tips for maintaining smooth, shiny hair, 2012.
• COSMOS-standard version 4.2 (2025), points 6.1.3, 6.1.4 and 12.3.2.