Endurance Supplements: What Works for Tested Athletes

Endurance supplements at a glance

What counts as an endurance food supplement?

Most of what endurance athletes use is closer to food than to a pill. The Australian Institute of Sport (AIS) puts sports drinks, gels, chews, sports bars and electrolyte supplements in Group A of its Sports Supplement Framework. Group A is its top group: strong evidence for use in specific situations.

The International Olympic Committee (IOC) describes the same products as practical ways to take in carbohydrate and fluid while you exercise. Some gels and chews also contain caffeine or electrolytes (minerals such as sodium).

The 2026 position statement from the National Athletic Trainers' Association (NATA) gives these sports foods its top evidence grade. When whole food is impractical, it says athletic trainers should recommend bars, gels, chews and sports drinks for carbohydrate and fluid.

Whole food still comes first. A banana, a sandwich and water do the same job on a training ride. Sports foods earn their place when you cannot carry or stomach real food at race pace.

How does the length of your event change what you need?

The NIH Office of Dietary Supplements (ODS) says endurance athletes might need extra fluid, electrolytes and carbohydrate when an activity lasts more than an hour. The same goes for exercise in heat or at altitude. A 2019 review of endurance nutrition splits it further:

• Under 60 minutes: you do not need carbohydrate during the event.
• Longer than 60 minutes: fueling during the event is recommended.
• Longer than 2.5 hours: more carbohydrate is linked to better performance, if you can tolerate it.

The bands come from the sources cited in this article. The grouping is our summary, not a chart any one source prints.

We leave out gram figures on purpose. How much carbohydrate your stomach can handle is individual, and a sports dietitian can build that plan with you in training. The IOC makes the same point about every performance supplement: try it in training that mimics competition before you use it in a race.

Which endurance supplements have good evidence?

Of all the products sold to improve performance, the IOC says only a few have good evidence: caffeine, creatine, some buffers and nitrate. For endurance athletes, the list is shorter still.

Caffeine

The IOC says caffeine has well established benefits in endurance events. The ODS says it is more likely to help endurance work than short, intense efforts like sprinting or lifting. NATA gives it its top evidence grade for endurance performance.

More is not better. The IOC warns that too much caffeine can cause nausea, anxiety, a racing heart and trouble sleeping, which can outweigh the benefit. For a tested athlete, the bigger issue is the rulebook, covered below.

Nitrate (beetroot juice)

In studies, beetroot juice has generally improved performance among runners, swimmers, rowers and cyclists, but not in every study. The IOC links nitrate to gains of 1 to 3 percent in time trials shorter than 40 minutes. A time trial is a race against the clock.

Training matters. The ODS says benefits are more likely in recreationally active people than in elite athletes. The IOC says gains appear harder to get in highly trained athletes.

Beetroot juice labels usually call the product a food, not a dietary supplement. Our guide to whether beet juice is banned by the NCAA covers its status.

Beta-alanine and sodium bicarbonate

Both are buffers. A buffer helps your muscles cope with the acid that builds up in very hard efforts. So they suit a few minutes of all out work, not a steady three hour ride.

• Beta-alanine. A review summarized by the ODS found a benefit mainly in efforts lasting 30 seconds to 10 minutes. NATA uses the same window. Our beta-alanine guide covers the tingling side effect and the NCAA status.
• Sodium bicarbonate. NATA describes effects in hard efforts lasting 30 seconds to 12 minutes, in cycling, swimming, running and rowing. The catch is your stomach. The ODS says responses vary, and that bicarbonate can make performance worse in some people.

What about creatine?

Creatine is well studied, but the ODS rates it of little value for endurance sports. A rower or swimmer doing repeated short, hard efforts is a different case from a marathoner.

What changes for cyclists, swimmers and rowers?

Most endurance advice is written for runners. Our guide to supplements for runners covers running, including iron. Three things change in other endurance sports.

• Race length varies more. A swimmer or rower may race for a few minutes, where buffers have their evidence. A road cyclist or long course triathlete may race for hours, where carbohydrate and fluid matter most. Pick by the length of your event, not the name of your sport.
• You can carry more. A bike holds drinks and bars. A pool swimmer cannot eat during a race at all. That changes which sports foods are practical, not which ones have evidence.
• The rulebook may not be the NCAA's. Many endurance supplement guides skip this part.

Do NCAA and WADA rules treat caffeine the same?

No. NCAA championships use the NCAA banned substances list. Sports that follow the World Anti-Doping Code use the Prohibited List of the World Anti-Doping Agency (WADA). The two lists treat two common endurance ingredients differently.

The U.S. Anti-Doping Agency (USADA) says the same: caffeine is permitted in WADA sports, but NCAA events limit it. If you compete under both sets of rules in one year, plan around the stricter one. Ask your compliance office or your sport's governing body which list applies to each race.

What changes if you are drug tested?

The science tells you what might work. The rules decide what it could cost you. The NCAA's warning is blunt:

• There are no NCAA approved supplements.
• Supplements, including vitamins and minerals, can cause a positive test.
• Supplements can be contaminated with banned substances that are not on the label.
• Third party tested products may be options, but "complete elimination of risk is impossible".

USADA says no supplement can be guaranteed 100 percent risk free. It recommends products certified by a third party program that tests for substances banned in sport. Third party means a company with no stake in the product does the testing.

Sports foods are the lower risk end of the shelf, but not a free pass. NATA notes that products sold as foods, with a nutrition facts label, face stricter FDA rules than supplements. It adds that contamination can still happen when active ingredients are added to foods.

NATA also names the supplement groups it says have been repeatedly linked to contamination:

• Muscle building and weight gainer formulas
• Fat burners
• Testosterone boosters and stimulant herbs
• Herbal products with many ingredients
• Proprietary pre workout blends

A proprietary blend hides the amount of each ingredient, which NATA says makes safety and compliance hard to judge. An "endurance booster" sold as a proprietary blend deserves the same caution.

Two habits from NATA are worth copying. Keep the packaging, or a record of the lot number, of every product you use. A lot (or batch) is one production run. Then check that the certification covers your exact lot, not just the brand. Our comparison of NSF, Informed Sport and BSCG explains what each program checks.

What can your school hand out?

A Division I rule, NCAA Bylaw 16.5.2.7, lets a school provide only six types of supplement, and only if they contain no NCAA banned substances:

• Carbohydrate and electrolyte drinks
• Energy bars
• Carbohydrate boosters
• Protein supplements
• Omega 3 fatty acids
• Vitamins and minerals

Half of that list is endurance fuel. The rule is marked as an area of autonomy, so each Division I subdivision may change it. Your compliance office has the final word.

Caffeine is in a banned class, so ask before you assume a caffeinated gel can come from the team. Our guide to energy gels in the NCAA goes deeper.

What about high school athletes?

The NCAA does not run high school sport. Your state association and school set the rules. This article gives no doses for anyone.

NATA says its recommendations come from studies in adults, so they should be applied to children and teenagers with caution. It adds that many developing athletes do not need performance supplements, because good fueling and a food first approach already support their growth and training. Talk to a doctor, athletic trainer or registered dietitian before starting any supplement.

What to check before you take an endurance supplement

1. Scan it in Varsity Stack first. Check the barcode or label against our certification database before you buy.
2. Match it to your event. A buffer does little for a three hour race, and a gel does little for a four minute one.
3. Know which rulebook tests you. The NCAA and WADA treat caffeine and synephrine differently.
4. Read every gel and chew for caffeine. Guarana, green tea extract and yerba mate count as caffeine on the NCAA list.
5. Try it in training. Never try a new product, or a new amount, on race day.
6. Choose certified, then check the lot. Look up the exact lot number on the certifier's own site, and keep the packaging.
7. Test before iron or vitamin D. Let a clinician decide from a blood test.
8. Keep a record. Add the product to your stack in Varsity Stack, so you and your staff know what you take. Keep a photo of the lot number too.

Check your endurance supplements with Varsity Stack

The easiest way to check an endurance supplement is the free Varsity Stack app. Scan it before you buy to see if it is certified, then add it to your stack so you and your staff know what you take.

Download the App

For coaches, sports dietitians and athletic trainers: the team dashboard shows every athlete's stack and whether each product is certified, so staff can review what athletes take.

Request access for your program

Varsity Stack does not laboratory test supplements, and certification lowers risk without removing it.