Cordyceps sharpened reaction time, not peak oxygen use

Cordyceps militaris is marketed heavily as an endurance and energy mushroom, yet the neuroprotective claims behind it come largely from chronic preclinical models rather than from humans taking a single dose. Exhaustive exercise is a useful stress test for the brain as well as the body: reaction time and inhibitory control shift measurably around maximal effort. Whether an acute dose can influence cognitive or physiological responses in that window had not been characterised in people. This crossover trial set out to test exactly that, with a single pre-exercise dose and objective measures on both sides.

Twelve recreationally active young men (mean age 21.6 years, VO2max 38.6 ml/kg/min) took part in a randomised, double-blind, placebo-controlled crossover trial with a 7-day washout between conditions. On each visit they ingested either 1 g of standardised Cordyceps militaris extract or a cornstarch placebo 30 minutes before a maximal cycling test to exhaustion. Cognitive performance was assessed with the Stroop task, capturing reaction time and accuracy. Physiological measures included oxygen uptake, blood glucose, blood pressure and heart rate, taken before exercise and three minutes after it.

Stroop reaction time showed significant main effects of both condition and time, with faster responses overall on Cordyceps. Both conditions improved from pre- to post-exercise, by 148.92 ms on placebo and 104.67 ms on Cordyceps, and the condition-by-time interaction was not significant. There was no difference between conditions before exercise, but reaction time after exercise was faster on Cordyceps (963.92 ms versus 1034.33 ms, d = 0.88). Accuracy stayed above 99% in both conditions with no difference. Resting oxygen uptake was higher on Cordyceps (0.37 versus 0.24 L/min) while peak exercise oxygen uptake, glucose, blood pressure and heart rate were unaffected.

This is a first human characterisation of acute effects, and it lands somewhere between the marketing and the null. The cognitive signal is real within the trial but modest in structure: because the interaction term was non-significant, the supplement appears to shift reaction time generally rather than change how exercise itself affects cognition — the authors' own reading. The higher resting oxygen uptake is intriguing but unexplained here, and it did not carry through to peak aerobic capacity, which is the outcome most buyers care about. Twelve young men, one dose, one session leaves nearly everything open.

If you have seen Cordyceps sold as something that raises your aerobic ceiling, this trial found no change in peak oxygen uptake. What it did find was a small cognitive edge on a reaction-time task, in a dozen young men, on a single occasion. Accuracy was already near-perfect in both conditions, so there was little room for the supplement to show anything there. Treat this as an early signal worth watching rather than a reason to expect either sharper thinking or better endurance from a jar of powder.