The short version
- Twenty-two trained male cyclists took 3g a day of CordyMax Cs-4 for five weeks and saw no change in VO2peak, ventilatory threshold or time trial performance.
- In 20 healthy adults aged 50 to 75, Cs-4 at 1g a day for 12 weeks raised metabolic threshold by 10.5% and ventilatory threshold by 8.5%, with no change in VO2 max in either group.
- The only trial that moved VO2 max used a mushroom blend rather than isolated cordyceps, and only ten participants completed its three-week arm.
- Cordyceps is not a stimulant, and in the trials where it did anything the change appeared over weeks in threshold and time-to-exhaustion measures rather than as an acute lift.
- That same trial found no significant effect on any measure after one week, which is how long many people give an ingredient before concluding it does nothing.
In 2004, twenty-two trained male cyclists at Brigham Young University took 3g a day of CordyMax Cs-4 for five weeks. Their VO2peak did not move. Their ventilatory threshold did not move. Their time trial did not move. The paper's title says it out loud: cordyceps supplementation does not improve endurance exercise performance.
That is the study cordyceps marketing never links to, and it is the right place to start — because the honest version of this ingredient is a small file with results pointing in different directions depending on who was taking it.
The older-adult trial
Chen and colleagues, 2010, in the Journal of Alternative and Complementary Medicine: twenty healthy subjects aged 50 to 75, double-blind and placebo-controlled, taking Cs-4 at 333mg three times daily for twelve weeks, with maximal incremental cycle ergometry and breath-by-breath analysis before and after.
Metabolic threshold — the intensity above which lactate starts to accumulate — rose 10.5%, from 0.83 ± 0.06 to 0.93 ± 0.08 L/min (p < 0.02). Ventilatory threshold rose 8.5%, from 1.25 ± 0.11 to 1.36 ± 0.15 L/min. Neither threshold changed significantly in placebo.
And then the sentence that matters: there were no changes in VO2 max in either group. The authors call it a pilot study, in twenty people.
So if you have seen "cordyceps raises VO2 max" attributed to this trial — and you will have — whoever wrote that did not read it. What moved was the intensity at which the wheels start to come off, not the ceiling on maximal oxygen uptake. Those are different physiological things, and the second one is the one printed on the label.
The trial that did move VO2 max, with asterisks
Hirsch and colleagues, 2017, in the Journal of Dietary Supplements: 28 participants, mean age 22.7, randomised, double-blind, placebo-controlled, taking 4g a day of a mushroom blend containing Cordyceps militaris or maltodextrin for one week. Ten volunteers continued for two further weeks.
After one week: nothing. No significant time-by-treatment interaction for VO2max (p = 0.364), ventilatory threshold (p = 0.514), time to exhaustion (p = 0.540), peak power (p = 0.134), average power (p = 0.398) or percent drop (p = 0.823).
After three weeks: VO2max improved significantly in the mushroom group (p = 0.042, +4.8 ml/kg/min) but not in placebo (+0.9). Confidence-interval analysis also showed improvements in time to exhaustion at one week (+28.1 s) and at three weeks (+69.8 s).
Three asterisks, all load-bearing. Only ten people completed the three-week arm. It was a blend, so you cannot attribute anything to cordyceps specifically. And a 4.8 ml/kg/min gain in three weeks is a large aerobic change by any standard, which in a group of ten should raise your eyebrow rather than your expectations.
How to read a file like this
Lay the three side by side. Nothing in trained endurance cyclists over five weeks, in the cleanest design of the set. Threshold improvements but no VO2 max change in untrained older adults over twelve weeks. VO2 max and time-to-exhaustion improvements in young adults after three weeks, in ten people, using a blend.
The most defensible reading is that the trained cyclists had the least headroom and the tightest methodology, and they got nothing — while the signals appear in people further from their ceiling, over longer durations, in smaller samples. Whether cordyceps does something meaningful for someone who is not already aerobically trained is a genuinely open question, and three small trials cannot close it. We are not going to resolve it in a blog post, and neither is anyone else's.
What cordyceps is not
It is not a stimulant. There is no caffeine in it and it does not behave like caffeine. If you take it expecting the lift of a pre-workout forty minutes later, you will conclude it does nothing — and by that standard you will be right. Whatever cordyceps does in these trials, it does over weeks, in threshold and time-to-exhaustion measures, not in how switched-on you feel this afternoon.
What we'd actually tell you
If you are a trained endurance athlete looking for an edge, the best-designed study in this set says no, and we would rather you spent the money on coaching.
If you are a desk worker who wants a non-stimulant option and is willing to run a twelve-week experiment on yourself, the doses that produced any signal were roughly 1g a day of Cs-4 — 333mg three times daily — or 4g a day of a militaris-containing blend. Give it the full duration. One of the two positive trials found literally nothing at week one, which tells you how quickly people quit and conclude the wrong thing.
And decide up front what would count as a result: a longer easy run at the same heart rate, a higher wattage held for twenty minutes, one extra interval at the same perceived effort. Pick the measure before you start. "I think I feel a bit better" is not a measurement, and it is the reason people stay on things that are doing nothing for them.
Good questions
Will cordyceps give me a lift like a pre-workout?
No. There is no caffeine in it and it does not behave like caffeine. If you take it expecting something forty minutes later you will conclude it does nothing, and by that standard you will be right. In the trials where cordyceps did anything, the change showed up over weeks in threshold and time-to-exhaustion measures.
Does cordyceps raise VO2 max?
One small trial says yes and two say no. In 20 older adults over 12 weeks, Cs-4 raised metabolic and ventilatory thresholds but VO2 max did not change in either group. In 22 trained cyclists over five weeks, nothing moved. Only a three-week arm of ten people, taking a blend rather than isolated cordyceps, showed a VO2 max gain.
Is cordyceps worth it if I already train seriously?
Probably not. The best-designed study in this file gave 3g a day of CordyMax Cs-4 to 22 trained male cyclists for five weeks and found no change in VO2peak, ventilatory threshold or time trial performance. Trained athletes have the least headroom. We would rather you spent the money on coaching, and we would rather say so plainly.
What dose of cordyceps was actually studied?
Roughly 1g a day of Cs-4, given as 333mg three times daily, or 4g a day of a Cordyceps militaris-containing blend. The blend matters, because nothing in that trial can be attributed to cordyceps specifically. Duration matters too: the trials ran twelve weeks and three weeks, and one of them found literally nothing at week one.
How will I know whether cordyceps is doing anything for me?
Decide what would count as a result before you start, and write it down. A longer easy run at the same heart rate, a higher wattage held for twenty minutes, one extra interval at the same perceived effort. Thinking you feel a bit better is not a measurement, and it is the reason people stay on things that are doing nothing.
Sources
- Parcell AC, Smith JM, Schulthies SS, et al. Cordyceps Sinensis (CordyMax Cs-4) supplementation does not improve endurance exercise performance. Int J Sport Nutr Exerc Metab, 2004. View study
- Chen S, Li Z, Krochmal R, et al. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects: a double-blind, placebo-controlled trial. J Altern Complement Med, 2010. View study
- Hirsch KR, Smith-Ryan AE, Roelofs EJ, et al. Cordyceps militaris improves tolerance to high intensity exercise after acute and chronic supplementation. J Diet Suppl, 2017. View study
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
