Cordyceps, Endurance and VO2Max: Clinical Trials Examined One by One, According to Studies

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Cordyceps

A concentrated 4:1 extract of Cordyceps militaris derived from the carpophore, that is to say from the mushroom itself and not from the mycelium, in vegetable capsules. Two capsules per day provide 1,800 mg of extract, to be taken in the morning or 30 to 60 minutes before exercise, in a course of at least 30 days. Vegan, GMO-free, gluten-free, and lactose-free.

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The word cordyceps practically designates four raw materials. The wild cordyceps sinensis, now named Ophiocordyceps sinensis, grows wild as a parasite of caterpillars, at high altitude, and is rare and expensive: the endurance trials identified here use cultivated preparations, or do not specify the origin of the material. The Cs-4 is a sinensis mycelium obtained by fermentation, the preparation used in trials from the 2000s. The Cordyceps militaris is another species, cultivated, of which either the fruiting body, the visible part of the mushroom, or the mycelium is used. Finally, several trials test blends where cordyceps sits alongside rhodiola, other mushrooms, minerals, or caffeine.

These forms are not interchangeable: a result obtained with one does not transfer to another, and each trial described below is presented with its exact form.

Our Cordyceps is a 4:1 concentrated extract of militaris fruiting body, at 1,800 mg of extract per two capsules: none of the trials in this file tested it, and none of their doses are equivalent to it. This file focuses on aerobic performance.

The first controlled double-blind trials on cordyceps and endurance involved cyclists. All three used cordyceps sinensis, in the form of fermented mycelium Cs-4 for the first two, alone or in a formula.

That same year, a trial in Medicine and Science in Sports and Exercise tested a commercial formula in 17 competitive amateur cyclists: three capsules provided 1,000 mg of Cs-4 and 300 mg of rhodiola root extract, plus 800 mg of pyruvate, phosphates, ribose and adenosine, and 200 µg of chromium. After 4 days at 6 capsules then 11 days at 3 capsules, peak VO2max (4.14 vs 4.10 L/min), time to exhaustion (38.5 vs 37.0 minutes) and maximum power (300 vs 291 W) did not differ from placebo. Two weeks of this formula is not enough, the authors concluded.

In 2005, part of the same team measured muscle oxygenation during maximal effort in 8 men, following a formula combining cordyceps sinensis and rhodiola, with the abstract not specifying the dose. Neither muscle oxygen saturation, nor VO2max, nor ventilatory threshold, nor time to exhaustion differed from placebo. This was the only trial in this review to have measured muscle oxygenation.

Change of population, change of results. The pilot trial from the University of California at Los Angeles recruited healthy adults aged 50 to 75 years.

The results concern thresholds, which are decisive for sustaining prolonged effort, but remain fragile: 20 participants, with no published replication since.

In young sedentary individuals, the 2019 Taiwanese trial examined whether cordyceps adds anything to training. Fourteen inactive young adults, 8 men and 6 women, completed 8 weeks of endurance training with a mixture of rhodiola and cordyceps at 20 mg per kilogram per day, or placebo. Training significantly improved endurance capacity and blood glucose in both groups, with no difference between them. Only body composition improved slightly better with the mixture, an effect judged as weak by the authors.

The University of North Carolina trial, published in 2017, is often summarized by its title: Cordyceps militaris would improve tolerance to intense effort. Twenty-eight adults aged 18 to 35 years, 16 men and 12 women, active at approximately five hours of exercise per week, took 4 g daily of a mushroom mixture or maltodextrin. The full text specifies that the mixture contained cordyceps mycelium biomass cultivated on oats, combined with other mushroom species; according to the authors it is militaris, and the 2026 review describes a mixture of six mushrooms with militaris as the main ingredient.

Three cautions are warranted. The three-week phase involved only 10 volunteers, which the 2026 review judges as carrying moderate bias risk. The product was a mixture, from which cordyceps cannot be isolated. And the participants were active but not endurance specialists, with baseline VO2max of 44 to 48 mL/kg/min depending on groups. A second trial on the same mixture, in adults aged 19 to 34 years, is described by the review as favorable at 1 to 2 g daily for 4 weeks (less lactate, higher peak VO2max); not indexed in PubMed, it could not be verified.

Our Cordyceps, extracted from fruiting body only, is neither mycelium cultivated on cereal nor a mixture: the results of this trial are not transferable to it.

At altitude. In 2014, a Taiwanese team followed 18 men during two weeks of training at 2,200 meters. Half took 1,400 mg of Rhodiola crenulata and 600 mg of cordyceps sinensis daily, the other a placebo. Running time to exhaustion improved by 5.7% with the mixture, versus 2.2% under placebo, and hemoglobin increased equally in both groups. The effect cannot be attributed to cordyceps alone, since rhodiola represented more than two-thirds of the mixture.

Long-distance runners. The 2024 Japanese trial is the longest: 22 university runners aged 18 to 24 years took 1,800 mg daily of Cordyceps militaris mycelium extract for 16 weeks, in six 300 mg capsules, or placebo. Time over 5,000 meters improved in both groups, with no difference between them. The differences were in blood markers: ferritin, reflecting iron reserves, increased with the extract while it decreased under placebo, hemoglobin and hematocrit increased slightly more at 8 weeks, and creatine kinase, a marker of muscle damage, was lower at 16 weeks. Hemoglobin, hematocrit and ferritin remained within normal ranges, with no difference between groups in absolute value, whereas creatine kinase exceeded normal levels at baseline in both groups. The capsules came from a company to which one of the authors is affiliated.

The figure of 1,800 mg is found on our Cordyceps label, but the coincidence ends there: the trial used mycelium extract, our product a 4:1 fruiting body extract.

Two marathoner trials, known through a meta-analysis. The 2025 meta-analysis describes two trials not indexed in PubMed. In the first, 12 trained runners of approximately 37 years took 3 g daily of cordyceps sinensis for 2 weeks, in a crossover trial: time to exhaustion, VO2max and second ventilatory threshold improved, with effects comparable to those of sodium bicarbonate. In the second, 22 amateur marathoners, 13 men and 9 women, took 2 g daily for 12 weeks: the 5 km time improved at the twelfth week, with no change in VO2max or thresholds.

Swimmers and runners. The 2026 review reports two other trials not indexed in PubMed: in 180 swimmers aged 16 to 18 years, 8 g of boiled militaris each evening for 7 weeks was associated with higher power output over 30 seconds; in 48 runners aged 16 to 35 years, 1 g of fresh ground fruiting body infused in black tea, with or without 10 g of whey protein, for 3 weeks reportedly maintained oxygen saturation at 93 to 95%, versus 60 to 75% in other participants, with faster times over 200 m and 5 km. An oxygen saturation of 60% in healthy runners would be highly unusual, and these figures require confirmation.

Among the five militaris trials retained by the 2026 review, none had tested a dose shorter than seven days. Two crossover trials explored single dosing, with results concerning other outcomes than aerobic performance.

A 2024 crossover trial with biopsies tested 1 g of Cordyceps sinensis, preparation not specified in the abstract, before interval exercise in 14 young adults: infiltration of necrotic cells in muscle, +284% three hours after exercise, was attenuated, and the arrival of stem cells earlier (+51%). This is data on muscle repair, not on endurance.

A single dose thus does not appear to change aerobic capacity, like the ineffective week of the 2017 trial; favorable results came from courses of 2 to 12 weeks. Taking our Cordyceps in the morning or 30 to 60 minutes before exercise, in a course of at least 30 days, is a brand usage recommendation, not a trial result.

The 2025 meta-analysis published in Frontiers in Nutrition pooled 14 randomized trials in 528 athletes, all mushroom types combined. For sinensis, it retained only three trials, at 2 to 3 g daily: the null trial in cyclists from 2004 and the two marathoner trials described above. The pooling shows an advantage in endurance at the margin of significance, across two trials (p = 0.05), and significant gains in ventilatory threshold (p = 0.03) and peak VO2max (p = 0.04), with low heterogeneity. The authors note that 13 of 14 trials were favorable, raising concerns about publication bias.

The 2026 narrative review devoted to militaris identified five published trials between 2017 and 2024, totaling 321 participants aged 16 to 35 years, at doses of 1 to 12 g daily for 1 to 16 weeks. None had low overall bias risk, four of five were not registered, none used a standardized preparation with measured active ingredient contents, and two involved blends. The authors judge the data insufficient to formulate recommendations.

The evidence level is an editorial assessment based on sample size, study design, and tested preparation. Trials known only through reviews are not included.

The most widespread argument holds that cordyceps increasesATP, the molecule that supplies energy to muscle. This stems largely from a 2001 study in mice: 7 days of Cs-4 mycelium aqueous extract at 200 or 400 mg per kilo per day increased liver ATP by 12.3% and 18.4% and decreased inorganic phosphate, measured by magnetic resonance. These values returned to baseline one week after stopping. This was in liver, not muscle, and in mice, not athletes.

<<<36>>> Cordycepin cordycépine, or 3'-deoxyadenosine, is the other lead. Its structure closely resembles adenosine, allowing it, according to the 2026 trial authors, to activate AMPK, an energy sensor that stimulates mitochondria. In mice, 20 or 40 mg per kilo of cordycepin for 28 days increased weighted swimming endurance and raised ATP and glycogen via the TIGAR, SIRT1, and PGC-1α pathway—the pathway for generating new mitochondria. Another team found increased endurance in mice in 2025. In rats, 200 mg per kilo of sinensis mycelium for 15 days multiplied swimming endurance by 1.79 without training, and by 2.9 with training, by activating AMPK, PGC-1α, and glucose and lactate transporters.

An extract of militaris slightly increased grip strength in animals, with little effect on fatigue markers. Conversely, in mice, exercise alone or sinensis alone protected the liver in an acute liver failure model, but not their combination, which the authors consider antagonistic; this model is very far removed from athletes.

The transition to humans remains the weak link: the two direct human measurements, muscle oxygenation and VO2max after single intake, showed no change.

Rhodiola appears in most blends tested with cordyceps, and has its own trials, which are more numerous.

A 2025 meta-analysis gathered 26 randomized trials in 668 healthy participants, with an average age of 22 years. Rhodiola rosea improved VO2max (effect size of 0.32 on 11 trials, a small effect), time to exhaustion (0.38 on 7 trials) and time trial (−0.40 on 5 trials, meaning shorter time), and reduced creatine kinase and lactate. VO2max gains were more pronounced beyond 600 mg per day, and the authors call for caution due to trial heterogeneity.

In 18 participants, 3 mg per kilo of rhodiola one hour before a time trial of approximately 9.7 km on a bike gained 0.4 minute and reduced perceived effort. Conversely, in 26 students, 600 mg per day for 4 weeks did not modify endurance capacity, while shortening reaction time. Its effects remain modest, more pronounced in acute intake, and absent from certain trials.

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Rhodiola (extract)

An extract of Rhodiola rosea root standardized to 1% salidrosides, in capsules. Two capsules per day provide 640 mg of extract, preferably in the morning, with a large glass of water.

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Our Rhodiola provides 640 mg of extract standardized to 1% salidrosides: this product has not been tested in these trials, whose extracts and standardizations differ. It is not recommended during pregnancy and breastfeeding, and requires professional medical advice if taking antidepressants.

Training. A meta-analysis of 28 controlled trials in 723 adults aged 18 to 45 years quantifies the VO2max gain at 4.9 mL/kg/min with continuous endurance training and 5.5 mL/kg/min with high-intensity interval training, compared to no exercise. Intervals perform slightly better, by 1.2 mL/kg/min on average. The gain from training alone, 4.9 to 5.5 mL/kg/min across 723 participants, is on the same order as the best result obtained with a mushroom blend, +4.8 mL/kg/min in 10 volunteers. The foundation remains moderate-intensity volume.

Caffeine. According to the position of the International Society of Sports Nutrition, aerobic endurance is the type of effort where caffeine provides the most consistent benefits, from moderate to large, at 3 to 6 mg per kilogram, most often 60 minutes before, or 210 to 420 mg for 70 kg. Very high doses, such as 9 mg per kilogram, multiply side effects without being necessary. See our article on caffeine before exercise.

Nitrates. A meta-analysis of 80 studies in Medicine and Science in Sports and Exercise finds a clear but small effect of dietary nitrates (0.17), in young and active men. It is not found in highly trained endurance athletes, with a VO2max of at least 65 mL/kg/min (0.02), nor in studies conducted exclusively in women.

The framework below is practical advice inspired by these principles; it does not reproduce the protocol of a trial.

In case of stagnation, consider iron, recovery and possible overtraining, and complement aerobic work with strength training.

Performance trials have not reported notable adverse effects, but they lasted at most 16 weeks, in small populations in good health. Documented risks relate to product quality and interactions.

Heavy metals. In Taiwan, two cases of lead poisoning were linked to a cordyceps powder containing up to 20,000 ppm of lead, with blood lead levels of 130 and 46 µg/dL, which returned to normal after discontinuation, with chelation therapy for the symptomatic patient.

Coagulation. An extract of militaris mycelium enriched in cordycepin slowed platelet aggregation in rats and clot formation in mice, without modifying coagulation time: animal data, which justify caution with anticoagulants or antiplatelet agents.

Immunosuppressants. In 202 kidney transplant recipients, 1 g of cordyceps sinensis three times daily was associated with lower doses and concentrations of cyclosporine between 2 and 6 months after transplant. After a transplant, it should never be taken without the approval of the medical team.

Doping control. For an athlete subject to testing, the documented risk in studies comes mainly from contamination of supplements. An analysis of 66 at-risk sports supplements purchased online found undeclared doping substances in 25 of them, or 38%, including stimulants and anabolic steroids. The athlete remains responsible for what they ingest, according to a leading review. The 2026 review on militaris even reports cases of products sold as cordyceps that contained anabolic steroids instead.

Athletes subject to testing verify the composition of any supplement with their federation before taking it, including our Cordyceps. Our guide to products banned in sport details the procedures.

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