Natural vs synthetic pre-workouts: what the evidence says

The global pre-workout supplement market is worth more than $15 billion and is built around a use case that has almost nothing to do with endurance sport. The category was designed for 45-minute gym sessions: high stimulant doses, short-burst performance ingredients, and label claims aimed at the strength and physique audience. Drop that product into a 4-hour ride or a marathon, and the formula fails on its own terms. The caffeine causes GI distress over the long haul. The beta-alanine tingling does nothing for sustained endurance. The artificial sweeteners trigger gut issues 90 minutes in. The "energy blend" turns into a cliff at hour three.

 

The natural versus synthetic framing is the wrong question. The right question is: which ingredients have evidence for sustained endurance performance, at the dose in the product, with the GI tolerance to last 3 hours or more? This article walks through what the research actually says, and where the OLEUS Pre-Activity Shot sits inside that evidence. For the broader picture of how a pre-activity formula fits into the 60 minutes before a session, see the 60-minute pre-training guide.

 

What does "natural" actually mean in supplement terms?

Natural and synthetic are not opposites in any way that matters for performance. Caffeine is the same molecule whether it is extracted from a Guarana seed or synthesised in a laboratory. Creatine monohydrate, one of the most-researched ergogenic aids in sport, is synthetic; it does not occur freely in any plant. Olive leaf extract is natural, but the standardised Oleuropein it contains has been processed and concentrated well beyond what eating an olive delivers. The dichotomy is marketing, not chemistry.

The honest distinctions that matter are different. Is the active compound delivered in a plant matrix that contains its natural cofactors, or as an isolated single molecule? Plant matrices often modulate absorption rate, which matters for endurance where slow release is preferable to sharp peaks. Has the compound been standardised so the dose is consistent batch to batch? Are the inactive ingredients (sweeteners, fillers, emulsifiers) ones the gut tolerates over hours of moderate-intensity effort? These are the questions that separate a useful endurance formula from a misapplied gym product.

The practical pattern for endurance formulations leans natural for one specific reason: plant-matrix compounds typically deliver slower-release activity with better GI tolerance over multi-hour efforts. That is mechanism, not philosophy. A synthetic compound with the same kinetic profile would be just as effective. There simply are not many of them.

 

Do traditional pre-workouts work for endurance athletes?

Most traditional pre-workouts work poorly for endurance athletes because they were not designed for the use case. The category was built around three goals: rapid stimulant activation, pumped-feeling vasodilation for the lifting set, and amino acid support for hypertrophy training. None of those goals align cleanly with endurance demands.

The stimulant doses are the clearest mismatch. Most commercial pre-workouts contain 250 to 400 mg of caffeine per serving, occasionally higher. According to the International Society of Sports Nutrition position stand on caffeine and performance, the ergogenic range for endurance is 3 to 6 mg per kg of body weight, taken 45 to 60 minutes before exercise. For a 70 kg athlete, that is 210 to 420 mg. The top of that range only matches the bottom of typical pre-workout dosing, and over a 3 to 5-hour effort the higher doses reliably produce GI distress, accelerated dehydration, anxiety-grade overarousal, and a sharp post-effort crash.

The "pump" ingredients (high-dose beta-alanine, large arginine doses, sometimes citrulline) are calibrated for short, high-intensity bouts where the vasodilation effect creates a felt sensation in the lifting set. For endurance, the relevant question is not "do I feel pumped" but "is blood flow being directed toward working muscle for the duration of the effort." Different mechanism, different doses, different formulation.

The amino acid component (typically BCAAs at 5 to 10 g) has weak evidence for any acute pre-exercise endurance benefit. Research summarised in the Journal of the International Society of Sports Nutrition indicates that BCAA supplementation pre-exercise does not meaningfully improve endurance performance in well-fed athletes, and in some cases compromises absorption of other amino acids needed for performance.

 

Which pre-workout ingredients have evidence for endurance performance?

A short list of pre-workout ingredients has solid evidence for sustained endurance performance specifically, as opposed to general gym performance. The list is shorter than most labels suggest:

Caffeine, at moderate doses. The strongest evidence base of any single pre-workout ingredient. The ergogenic range is 3 to 6 mg per kg of body weight, taken 45 to 60 minutes before exercise. For endurance, the lower half of this range delivers most of the benefit with far fewer side effects than the upper half. Natural sources like Guarana extract release caffeine slightly more gradually than isolated caffeine anhydrous, which improves tolerance over multi-hour efforts.

L-Citrulline. Research published in the Journal of the International Society of Sports Nutrition shows that L-citrulline supplementation improves cycling time trial performance and reduces muscle fatigue ratings in trained men. The compound converts to L-arginine in the kidneys, raises nitric oxide, dilates blood vessels, and improves oxygen delivery to working muscle. The effective dose range for acute performance is 3 to 6 grams of free-form L-citrulline. Most pre-workouts include 500 to 1,000 mg or include "citrulline malate" without disclosing how much is citrulline. Both fall short of clinical efficacy.

Dietary nitrates (beetroot). Strong evidence for improved oxygen economy and reduced oxygen cost of sub-maximal exercise. The effective dose is 5 to 9 mmol of nitrate, typically delivered as concentrated beetroot juice or a beetroot extract powder. Less common in traditional pre-workouts because the bitter, earthy taste does not blend well with sweet stimulant flavour profiles.

Polyphenols. Plant compounds including oleuropein (from olive leaves), curcumin, tart cherry anthocyanins, and several others. The evidence is younger than for caffeine or citrulline but growing, particularly for compounds with direct mitochondrial mechanisms. For the broader science of plant-based antioxidants in endurance sport, see the Plant-based antioxidants guide.

Magnesium and B-vitamin cofactors. Not ergogenic on their own. The enzymatic foundation that ATP production depends on. Underdosed in most pre-workouts because the focus is acute stimulation rather than cellular support.

 

Which pre-workout ingredients underperform for endurance?

Several common pre-workout ingredients have evidence for some use cases but weak or contradictory evidence for endurance specifically. The presence of these ingredients on a label is not necessarily a problem, but the marketing claims around them often outrun the science for the endurance use case.

Beta-alanine. Strong evidence for events lasting roughly 1 to 4 minutes at high intensity (rowing 2K, 800-1500m running, certain CrossFit work) according to the ISSN position stand. Weak evidence for events over 60 minutes. The tingling sensation (paraesthesia) is well-known but is not an indicator of efficacy. For most endurance athletes, beta-alanine is taking up label space that could be allocated to better-evidenced compounds.

BCAAs. Marketed heavily as a performance and recovery ingredient. Evidence for acute pre-exercise endurance performance in well-fed athletes is weak. The amino acid profile (leucine, isoleucine, valine) does support muscle protein synthesis, but the timing window pre-exercise is not where this matters most.

Proprietary blends. Not an ingredient. A label structure that hides individual doses inside a sum. "Endurance Performance Blend: 2,500 mg" with seven ingredients tells you nothing about how much of any one ingredient you are getting. The first ingredient takes up most of the 2,500 mg by weight, and the last ingredients may be present in symbolic amounts. The structure exists because it lets manufacturers underdose expensive actives without disclosure.

Artificial sweeteners at high doses. Sucralose, ace-K, and aspartame are not health risks at standard intakes. They are, however, common causes of GI distress during prolonged exercise. For a 4-hour ride, the cumulative sweetener load from a pre-workout plus sports drinks plus gels can push the gut past tolerance. Endurance formulations generally use less aggressive sweetening or rely on natural carbohydrate flavour.

 

Why does GI tolerance matter so much for endurance pre-workouts?

A pre-workout product is taken 45 to 60 minutes before exercise. For a gym athlete, that means the product is digested and the effects peak during a 45 to 75-minute session. For an endurance athlete, the product is still in the gut at the start, and the gut is still processing its ingredients 2, 3, or 4 hours into the effort while the athlete is also taking on sports drink, gels, real food, and water. The cumulative load is meaningfully higher.

This is why ingredients that "work fine in the gym" can fail catastrophically in endurance contexts. High-dose caffeine accelerates gastric emptying initially, then slows it as dehydration progresses. High-dose beta-alanine produces sensory symptoms that are tolerable for 20 minutes and distracting for 3 hours. Artificial sweeteners that produce no symptoms in a single morning serving can cause cramping when stacked with on-course gels. The endurance gut tolerates monotony better than novelty and tolerates low-residue better than concentrated.

The practical implication is that an endurance pre-workout should not just have evidence-based actives. It should have evidence-based actives delivered in a format the gut tolerates over hours of moderate-intensity work. Most traditional pre-workouts fail this second test even when they pass the first.

 

What should you look for on a pre-workout label?

Ingredient	Endurance evidence	Common commercial dose vs efficacious dose	GI tolerance over 3+ hours
Caffeine	Strong (moderate dose)	Commercial 250 to 400 mg vs efficacious 3 to 6 mg per kg	High doses cause GI distress and crash
L-Citrulline	Strong	Often 500 to 1,000 mg vs efficacious 3 to 6 g free form	Generally well-tolerated
Nitrate (beetroot)	Strong	Variable; efficacious 5 to 9 mmol nitrate	Generally tolerated; some staining
Oleuropein (olive leaf)	Emerging; mitochondrial mechanism	Rarely included; efficacious 50 to 100 mg	Well-tolerated
Beta-alanine	Limited for endurance	Common 1.5 to 6 g	Tingling sensation; not GI
BCAAs	Weak for endurance performance	Common 5 to 10 g	Higher at large doses
Creatine monohydrate	Limited for endurance (strong for sprint/power)	3 to 5 g; usually adequate	Generally well-tolerated
Proprietary blend	Cannot be evaluated	Doses hidden by definition	Unknown

 

Four practical rules apply when reading a label:

1. Look for individual doses listed for every active, not blend totals.
2. Match each dose against the efficacious range from research, not against what looks impressive on the label.
3. Consider the GI profile of the inactive ingredients (sweeteners, fillers) over the duration of your typical effort.
4. Weigh the caffeine dose against your body weight and your sensitivity, not against the maximum the FDA allows.

 

How the OLEUS Pre-Activity Shot was built around these principles

The Pre-Activity Shot was designed around the evidence above, not around the conventions of the pre-workout category. Each compound is there for a mechanism that has research behind it for endurance specifically. Each dose is published on the label, no proprietary blends. The plant-matrix sources were chosen for absorption kinetics and GI tolerance, not for marketing language.

The formula delivers 80 mg of caffeine, calibrated to the lower end of the 3 to 6 mg per kg range, which is the dose level that delivers most of the endurance benefit with the fewest side effects over multi-hour efforts. 885 mg of L-citrulline supports nitric oxide production and blood flow. 375 mg of Acetyl-L-carnitine supports fatty acid transport into the mitochondria, relevant for efforts where fat becomes a meaningful fuel source. 100 mg of Oleuropein covers the mitochondrial-support and oxidative-stress mechanisms covered in the antioxidants pillar. 56.3 mg of magnesium and the full B-vitamin complex provide the enzymatic cofactors. 15 mg of vitamin C and 27.5 mg of sodium round out the formulation.

What is not in the formula matters as much. No mega-dose caffeine. No proprietary blend. No high-dose beta-alanine, since beta-alanine has weak endurance evidence. No isolated BCAAs at acute doses, since the pre-exercise window is not where they matter most. No artificial sweetener load designed to mask a chemistry-set ingredient deck. The full label breakdown is in the Pre-Activity Shot ingredients article.

 

We did not design against the pre-workout category. We designed for the endurance use case and ignored the category. The result happens to look natural because plant matrices delivered better kinetics for the multi-hour use case. The category convention is the consequence, not the goal.

OLEUS Performance Lab

 

What does the clinical research show?

The OLEUS formula was evaluated in a placebo-controlled trial with 28 cyclists from a Switzerland-based World Tour professional cycling team. The protocol involved a multi-day endurance test, comparing the oleuropein-based formula against a placebo across sustained power output, perceived exertion, and recovery markers. The riders taking the formula showed +25% sustained power output over the test period compared to the placebo group.

The trial tested the integrated formula, not isolated ingredients in test tubes. The result is what an endurance athlete cares about: sustained performance over a multi-hour, multi-day effort, in trained athletes, against placebo. More than 5,000 endurance athletes across Belgium, the Netherlands, Switzerland, and beyond now use the OLEUS system as their pre-activity standard.

 

Frequently asked questions

 

Is it dangerous to take a high-caffeine pre-workout before a long run?

Dangerous overstates it for most athletes. Counter-productive understates it. Doses in the 300 to 400 mg range over a 3 to 5-hour effort reliably cause some combination of GI distress, accelerated dehydration, anxiety-grade overarousal, sleep disruption later in the day, and a hard post-effort crash. None of these is dangerous in the clinical sense, and all of them compromise performance. The 3 to 6 mg per kg range exists because the research shows benefits taper above it and side effects climb.

 

Does beta-alanine help endurance athletes?

Modestly, for some specific contexts. The strongest evidence is for events lasting 1 to 4 minutes at high intensity, where the carnosine buffer that beta-alanine builds up over weeks of supplementation reduces acid accumulation. For events over 60 minutes, the evidence is weaker. For most endurance athletes whose A-races are longer than that, beta-alanine takes up label space that could be allocated to compounds with stronger endurance evidence.

 

What is wrong with proprietary blends?

The structure hides individual doses inside a sum. A "2,500 mg Endurance Blend" with seven ingredients tells you nothing about how much of any one ingredient you are getting. The first ingredient by weight takes up most of the 2,500 mg, and the last ingredients may be present in symbolic amounts. The structure exists because it lets manufacturers list expensive actives on the label at sub-efficacious doses without disclosure. A transparent formula lists every dose individually.

 

Can I take a regular pre-workout for endurance training?

You can, but you are using a tool designed for a different job. The compounds that matter for short-burst gym performance (high-dose caffeine, high-dose beta-alanine, aggressive sweetener loads, sometimes creatine and BCAAs) overlap only partially with what serves a multi-hour endurance effort. A formula calibrated for endurance will outperform a gym pre-workout for endurance use, and vice versa.

 

How is the OLEUS Pre-Activity Shot different from a traditional pre-workout?

Five differences. Caffeine is moderate (80 mg from Guarana) rather than mega-dose. Active compounds are plant-matrix sourced for slower-release kinetics. Every dose is printed on the label, no proprietary blends. The formulation prioritises endurance-specific mechanisms (Oleuropein for mitochondrial support, L-citrulline for blood flow, Acetyl-L-carnitine for fat oxidation) rather than gym-session mechanisms. And the GI tolerance is designed for multi-hour efforts rather than 45-minute sessions.

 

The bottom line

The natural versus synthetic framing is the wrong question. The right one is: does the ingredient have evidence for endurance, at the dose in the product, with the GI tolerance to last hours? Most pre-workouts on the shelf fail at least one of those tests because they were not built for the endurance use case. The OLEUS Pre-Activity Shot was.

 

Sources

1. Goldstein, E.R., Ziegenfuss, T., Kalman, D., Kreider, R., Campbell, B., Wilborn, C., Taylor, L., Willoughby, D., Stout, J., Graves, B.S., Wildman, R., Ivy, J.L., Spano, M., Smith, A.E., Antonio, J. (2010). International Society of Sports Nutrition position stand: caffeine and performance. Journal of the International Society of Sports Nutrition, 7(1), 5.

2. Suzuki, T., Morita, M., Kobayashi, Y., Kamimura, A. (2016). Oral L-citrulline supplementation enhances cycling time trial performance in healthy trained men. Journal of the International Society of Sports Nutrition, 13, 6.

3. Bailey, S.J., Winyard, P., Vanhatalo, A., Blackwell, J.R., Dimenna, F.J., Wilkerson, D.P., Tarr, J., Benjamin, N., Jones, A.M. (2009). Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. Journal of Applied Physiology, 107(4), 1144-1155.

4. Trexler, E.T., Smith-Ryan, A.E., Stout, J.R., Hoffman, J.R., Wilborn, C.D., Sale, C., Kreider, R.B., Jäger, R., Earnest, C.P., Bannock, L., Campbell, B., Kalman, D., Ziegenfuss, T.N., Antonio, J. (2015). International Society of Sports Nutrition position stand: beta-alanine. Journal of the International Society of Sports Nutrition, 12, 30.

5. Wolfe, R.R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? Journal of the International Society of Sports Nutrition, 14, 30.

6. Jeukendrup, A.E. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33.

7. OLEUS placebo-controlled trial, 28 cyclists, Switzerland-based World Tour team, multi-day endurance protocol. Data on file, OLEUS Performance Lab.

This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.