Which HYROX Supplements Are Still Worth Starting Before Your Race

A list of HYROX supplements tells you what exists, not what still has time to work before your race. For several of the best-supported options, that depends on how many weeks you have left: beta-alanine and creatine build up in muscle over days to weeks, and sodium bicarbonate and beetroot juice need rehearsing in training first. Grades below are from the Australian Institute of Sport (AIS) Sports Supplement Framework, lead times from the AIS fact sheets and the International Olympic Committee (IOC) 2018 consensus statement, and the race-week rule from RoxTribe's taper-week guide. All of it sits on top of the training block.

The ladder: count back from your race date

Find the row for your race date, then read across.

Your race is	Still worth starting (AIS group)	Rehearse in training first, do not start cold	Leave for your next race
Ten weeks or more away	Beta-alanine (Group A), with time for at least the shorter end of the IOC protocol. Creatine (Group A), either route. Iron or vitamin D (Group A, medical): only on a doctor's advice	Sodium bicarbonate (Group A): the AIS sequence, starting with a trial at rest, then hard sessions. Beetroot juice (Group A): practise before a hard session. Then rehearse both at race-morning timing in a full simulation	Nothing on timing grounds
Four weeks or more, but under ten	Beta-alanine (Group A): meets the AIS minimum, short of the IOC protocol. Creatine (Group A): the loading route, or the no-loading route only if its roughly four-week build (AIS) still leaves training weeks before race week. Iron or vitamin D (Group A, medical): only on a doctor's advice	Sodium bicarbonate (Group A): the AIS sequence, starting with a trial at rest, then hard sessions. Beetroot juice (Group A): practise before a hard session. Then rehearse both at race-morning timing in a full simulation	Nothing on timing grounds
Under four weeks, before race week	Iron or vitamin D (Group A, medical): only on a doctor's advice	Beetroot juice (Group A), if a hard session before race week can carry the trial. Sodium bicarbonate (Group A) only if already trialled through the AIS sequence	Beta-alanine: under the AIS 4-week minimum. Creatine: the no-loading route cannot saturate in time, and a late load leaves little or no training to judge the extra body weight it can add (RoxTribe's reasoning). Bicarbonate not yet trialled
Race week	Nothing	Nothing. Keep only what you already take	Every new product
Race morning	Nothing new	Only the items you have already rehearsed. Caffeine (Group A): see the race-day guide	Anything untested

The ten-week line is the IOC's 10-to-12-week beta-alanine protocol; the four-week line is the AIS's 4-week beta-alanine minimum and its figure of about 4 weeks for creatine to reach saturation without loading.

The rehearse-first column follows the IOC's line that performance supplements should be thoroughly trialled in training or simulated competition before competition, and the AIS's four-phase bicarbonate introduction. Groups B, C and D sit on no row at any date; their grades, in the next section, say why.

A row shows what is still possible; whether to take any of it is your call, ideally with a sports dietitian. Any nutrition or supplement you plan to take after the start has a rule attached, because any racer who wants nutrition must carry it from the start of the race, and may not accept any beverage or nutritional product from anyone except the aid stations. See the race-day guide.

How HYROX supplements are graded, and who grades them

The AIS ranks sports foods and supplement ingredients into four groups by the evidence and by whether a product is safe, permitted in sport and effective. Group A has strong evidence for use in specific situations. B covers emerging or mixed support, for individual athletes in research or clinical monitoring, while C is for evidence that does not support a benefit, or no research, and is not advocated. D is banned or at high risk of contamination that could cause a positive doping test, and is not to be used.

The AIS writes for high-performance athletes, and its policy template targets elite sports bound by the World Anti-Doping Agency's list; the IOC statement also addresses the high-performance athlete. Neither singles out HYROX. The grades still transfer, because they rest on what the evidence says a supplement does, with the IOC flagging where training status changes that, and because HYROX applies an anti-doping policy too.

The IOC statement says only a few supplements, including caffeine, creatine, specific buffering agents and nitrate, have good evidence of benefits, and adds beta-alanine as "possibly also" supported for marginal gains.

Item	AIS group	What the evidence covers
Creatine monohydrate	A	High-intensity bouts under 150 seconds, most pronounced under 30 seconds (IOC); a training aid for strength blocks (AIS)
Beta-alanine	A	Efforts of 30 seconds to 10 minutes, a small but potentially meaningful benefit (IOC)
Sodium bicarbonate	A	Sprints of around 60 seconds, less effective as efforts pass 10 minutes (IOC)
Dietary nitrate (beetroot juice)	A	Time trials under 40 minutes; intermittent team-sport exercise of 12 to 40 minutes (IOC)
Caffeine	A	See the race-day guide
Sports drinks, gels, electrolyte supplements, isolated protein	A (sports foods)	Fuel and protein: see the nutrition guide on fuelling and HYROX electrolytes
Iron, vitamin D	A (medical)	Correcting a deficiency found by assessment (IOC)
Fish oil, collagen, fruit polyphenols such as cherry, multivitamins, probiotics	B	Emerging or mixed support (AIS)
BCAAs, HMB, magnesium	C	Not supportive of benefit, or not researched (AIS)
Stimulants such as DMAA and DMBA, prohormones, SARMs, higenamine	D	Banned or at high risk of contamination (AIS)

Check the product before the first dose

This step applies whatever your date. The Season 26/27 Singles rulebook puts the rule in one line: compliance with the HYROX anti-doping policy is required at all times. Its anti-doping section adds that all racers "are expected to comply with the organisers' antidoping regulations", which includes "submitting to testing for banned substances, both in and out of the race", and that HYROX "reserves the right to conduct random testing at any time".

The detail is in the HYROX Anti-Doping Code. Its title names the Elite Division, but its preamble says: "All athletes participating in HYROX events are expected to comply with this HYROX-ADC." It uses WADA's Prohibited List, and its Article 2.1.1 makes athletes responsible for any prohibited substance found in their sample, with no need to show intent, fault, negligence or knowing use.

A label is not enough, though it still needs reading. The IOC statement names two routes to an inadvertent positive: a prohibited substance on the label that the athlete fails to recognise, and, as "the most worrying cause", one carried as an undeclared ingredient or contaminant. It reports that the original study found about 15% of more than 600 products bought around the world contained undeclared prohormones, though such studies rarely use a truly random sample, and adds that vitamin C, multivitamins and minerals have also, rarely, been found to contain prohibited substances.

UK Anti-Doping says no supplement is guaranteed free from banned substances and that, under strict liability, athletes are solely responsible for any prohibited substance in their system. It advises only batch-tested products, with the actual batch number checked before use, points athletes to Informed Sport, and calls any claim of WADA or UKAD approval inaccurate. USADA says no supplement can be guaranteed "100 percent risk-free" and recognises NSF Certified for Sport. The AIS fact sheets point to the Sport Integrity Australia app's batch-tested list, and say batch-tested products carry the lowest risk but no guarantee. In the IOC's words, there is "no absolute guarantee that any product is entirely safe", but these schemes "do help the athlete to manage the risk".

In practice, check every product before its first dose, and look up the batch you bought, not just the product name.

Iron and vitamin D: a doctor before the bottle

Iron and vitamin D are AIS Group A medical supplements. For them the ladder starts at a clinic, because the IOC statement says deficiencies should first be identified through nutritional assessment, including the appropriate blood or urinary marker if available. UK Anti-Doping's advice for any supplement is to ask a qualified medical professional whether you need it. The IOC adds that high-dose iron should not be taken unless iron deficiency is present, and warns that iron taken with adequate stores can cause symptoms that may begin with vomiting and abdominal pain and develop into haemochromatosis and liver failure. The AIS says iron supplements should only be taken under medical supervision.

Both take time. The AIS iron fact sheet describes a course of 8 to 12 weeks, confirmed by a follow-up blood test, and its vitamin D fact sheet says restoring low status takes 1 to 2 months, followed by another blood test. That sheet also supports vitamin D for athletes at risk of deficiency, such as those with little sun on the skin, without a diagnosed shortfall. Either way, the first step is a doctor, not a shelf.

Beta-alanine and creatine, the slow loaders

Both build a store in muscle with daily use, so one pre-race dose does not reproduce either framework's protocol.

Beta-alanine: the AIS and the IOC give different lead times

The AIS beta-alanine fact sheet advises a minimum of 4 weeks for a performance benefit, starting about a month before the training block or competition it targets. The IOC protocol runs over 10 to 12 weeks. The AIS figure is a minimum; the IOC figure is a full protocol.

The HYROX fit is imperfect. The IOC finds small but potentially meaningful benefits in efforts of 30 seconds to 10 minutes. A HYROX is eight rounds, each a 1 km run followed by one functional workout station, so no finish comes anywhere near ten minutes. What keeps it relevant is another AIS category: high-intensity efforts within or at the end of prolonged exercise, such as distance running.

The IOC adds that the benefit appears harder to realise in well-trained athletes, and side effects include skin tingling that can last up to an hour (AIS) and skin rashes (IOC).

Creatine, and the weight question HYROX makes sharper

The AIS describes two routes: loading for about 5 days, or skipping loading and saturating over about 4 weeks; the IOC's loading phase runs 5 to 7 days. The AIS sees no scientific reason to use any form but monohydrate, suggests skipping loading to help avoid stomach upset, and treats creatine as a training aid for phases such as a heavy strength block.

The IOC puts the potential body-mass gain after loading at 1 to 2 kg, primarily water, and the AIS says it may only be a maximum of 1 or 2 kg. In the IOC's view, that gain may be detrimental for endurance performance, or where body mass must be moved against gravity. The AIS takes the other view for body-weight-supported sports such as running, saying the concern appears unfounded and citing studies that showed improved running and swimming performance. That extra mass rides with you through 8 km of running and all 8 stations, and the trade is yours to weigh.

The AIS says body mass returns to normal slowly, over 4 to 6 weeks after stopping, so stopping in race week would not shed it in time. It also advises that, as with any dietary supplement, experimentation should be done in the off-season, advice that draws no line in weeks.

Race-morning items that need a rehearsal first

Bicarbonate and beetroot juice can be taken in the hours before a start, so they look like race-week decisions. They are not, because both frameworks want them rehearsed first.

Sodium bicarbonate comes with a trial programme, not a trial run

The AIS bicarbonate fact sheet recommends a four-phase approach to building an individual protocol:

1. Preparation, including time in the training schedule for multiple trials.
2. Isolated trials at rest, measuring gut symptoms and the buffering response.
3. Trials during high-intensity training sessions.
4. Competition, where some athletes pick a lower-priority event.

From the trials at rest onward, each phase measures gut symptoms and the buffering response, and the last two add training or competition performance. The AIS names gastrointestinal distress (nausea, stomach pain, diarrhoea and vomiting) as the major side effect and says it may counteract the potential performance benefits. The IOC times bicarbonate 60 to 150 minutes before exercise, or across the 2 to 4 days before an event.

For a HYROX, the evidence cuts both ways. The IOC finds about a 2% gain in sprints of around 60 seconds, with reduced efficacy as efforts pass 10 minutes. The AIS adds that high-intensity events of about an hour or more, raced just below threshold, may also be relevant for surges and sprint finishes. And an athlete selected for a drug test may need to wait several hours for urine pH to return to levels testing authorities accept, the AIS notes, which matters given the testing rules above.

Beetroot juice and nitrate

Beetroot juice is a source of dietary nitrate. The IOC reports acute benefits within 2 to 3 hours of intake and says more than 3 days of intake also appears beneficial; the AIS times it about 3 hours before an event, or daily for several days before it. Gains appear harder to obtain in highly trained athletes, the IOC adds. The AIS notes antibacterial mouthwash may markedly limit the effect, and advises practising in training first because of possible mild stomach discomfort. A full HYROX simulation is the place to rehearse the timing.

From race week to the start line: nothing new

Once race week starts, start nothing new. RoxTribe's taper-week guide puts it plainly: taper week is "the worst possible time to try a new supplement". Keep what you already take, as you already take it. On race morning, use only what you have rehearsed, as you rehearsed it. Any nutrition or supplement for after the start falls under the carry rule below the ladder; see the race-day guide.

Putting the ladder on a calendar

Here is the ladder with twelve weeks to go, as an example, not a recommendation. Each step draws on a source above.

1. This week: list everything you take and check each product and batch against the batch-tested list your anti-doping agency points to. If you suspect low iron or vitamin D, see a doctor first.
2. Also this week, if you choose them: beta-alanine, with time for the full IOC protocol, and creatine by either AIS route.
3. Your next easy week: a first bicarbonate trial at rest, the AIS's second phase, if bicarbonate is on your list.
4. Hard sessions after that: bicarbonate trials in training (the AIS's third phase) and beetroot juice practice.
5. Your last full simulation before race week: the dress rehearsal, at exact race-morning timing. On the twelve-week plan, that is its late simulation phase.
6. Race week: nothing new.
7. Race morning: the rehearsed plan, and nothing else.

What stays off the ladder entirely

• Sports foods. Group A, but fuel rather than loading supplements; the HYROX nutrition guide covers them.
• Pre-workout blends. The AIS treats beta-alanine in pre-exercise formulas as acute supplementation, which it finds no evidence for, and it flags some ingredients not on the WADA list, synephrine and tribulus among them, as often found in multi-ingredient products that contain banned ingredients or are at high risk of contamination. A single-ingredient, batch-tested Group A product, used on its protocol, sidesteps the first problem and lowers the second.

A sports scientist's own shortlist, on video

Nicklas Rossner, who describes himself as a former professional triathlete with degrees in sport science and physiotherapy, runs through the supplements he rates for endurance running and ends with his own three-tier shortlist, not the AIS groups. He also says to test beetroot juice in training first. His doses are his; this page gives none.

Frequently asked questions about HYROX supplements

Which HYROX supplements have the strongest evidence?

The AIS puts creatine, beta-alanine, sodium bicarbonate, beetroot juice and caffeine in Group A, its strongest grade. The grade is half the answer: beta-alanine needs weeks, creatine days to weeks, and bicarbonate and beetroot juice need trials in training, so your race date decides.

How early would creatine have to start before a HYROX race?

It depends on the route. The AIS gives about five days if you load, or about four weeks to reach saturation if you skip the loading phase, and it advises experimenting with any supplement in the off-season. RoxTribe's own view: start early enough to judge, in training before race week, the extra body weight creatine can add.

Has the window for beta-alanine closed before my race?

It has if the race is under 4 weeks away, going by the AIS's minimum for a performance benefit. With at least 4 but under 10 weeks left you clear that minimum but cannot fit the IOC's 10-to-12-week protocol; with 10 or more you can fit at least its shorter end.

Is creatine's weight gain a problem for HYROX running?

The two frameworks lean different ways. The IOC warns that a potential 1 to 2 kg gain may hurt endurance performance, while the AIS treats 1 or 2 kg as a ceiling and calls the worry for running apparently unfounded. Over 8 km of running, you decide.

Where does a pre-workout fit in HYROX training?

Judge it by its contents, as the AIS grades ingredients and sports foods. Synephrine, tribulus and maca root are absent from the WADA list, yet the AIS says they often turn up in combination products that also hold banned ingredients or carry a high contamination risk. It finds no evidence that a single pre-session dose of beta-alanine helps.

What does a sodium bicarbonate trial involve?

Several sessions spread through your training, not one test. The AIS sequence moves from preparation to trials at rest, then hard training, and finally competition, which some athletes make a lower-priority race. From the rest trials on, each step logs gut symptoms and buffering, and the AIS warns gut distress may counteract the benefit.

Is beetroot juice less useful for a highly trained racer?

Both frameworks say it can be. The AIS says aerobic fitness influences how well dietary nitrate works and reports that highly trained endurance athletes did not benefit significantly. The IOC says gains appear harder to obtain for the highly trained, and that more than 3 days of intake may help them.

Could a supplement lead to a failed drug test at HYROX?

It could, by more than one route. The IOC names athletes missing a prohibited substance printed on the label, and products carrying one undeclared or as a contaminant; UK Anti-Doping adds that labels can be inaccurate. The Singles rulebook's anti-doping section covers "submitting to testing for banned substances, both in and out of the race".

What grade do fish oil, collagen and cherry get from the AIS?

Group B. The AIS uses that grade for emerging or mixed scientific support, and considers Group B items for identified individual athletes within research or clinical monitoring situations. Cherry sits there among the fruit-derived polyphenols, alongside berries, blackcurrants and pomegranate, all graded the same way.

Can a new supplement go into race week?

No. Race week leaves no room to find out how a product sits with you, which is why the taper-week guide warns against new supplements then. The IOC's advice concerns order, not dates: it says a performance supplement should be tried in training or a race simulation before you rely on it in competition.

References

• Australian Institute of Sport, Sports Supplement Framework. The ABCD classification and its audience.
• AIS framework, Group A, which links the AIS fact sheets cited throughout.
• AIS framework, Group B, Group C and Group D, including the Group D footnote on synephrine, tribulus and maca root.
• Maughan RJ, Burke LM, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med, 2018. Open access full text.
• HYROX Singles Rulebook, Season 26/27. Anti-doping and nutrition rules.
• HYROX, official rulebook page. Links the Anti-Doping Code quoted above and the TUE form.
• UK Anti-Doping, Managing Supplement Risks.
• USADA, Supplement Connect.

RoxTribe is an independent community resource and is not affiliated with HYROX.