The three best-powered cordyceps trials found no fitness gain
In three trials of 135 people in all, oxygen uptake, ventilation and anaerobic power sat where placebo left them. Everyone studied was young and already trained.
What the study found
Across three trials and 135 people, no exercise measure moved
The largest gave 96 students a month on Ophiocordyceps sinensis, the wild caterpillar fungus, blended with a second mushroom. VO2max, ventilation and anaerobic power sat where placebo left them. Two more ran Cs-4, a fermented mycelium, one on the maker's own schedule, and matched it.
The caveat · Young and trained, little to gain
Two of the three tested multi-ingredient products, one of them eight ingredients deep, so none of this isolates cordyceps from what it was mixed with. Every participant was young and already trained, which is where there is least room left to improve. The shortest of the three ran fifteen days.
What we don't know
Whether cordyceps improves endurance is unsettled. A pooled analysis reports gains that only just clear chance, while the three best-powered single trials found none, which says more about how thin this research is than about who is right.