Xiao Y., Huang X., Zhu J. Randomized double-blind placebo-controlled clinical trial and assessment of fermentation product of Cordyceps sinensis (Cs-4) in enhancing aerobic capacity and respiratory function of the healthy elderly volunteers. Chin J Integr Med. 2004;10(3):187–192.
Rationale
Cordyceps sinensis (CS) is a traditional Chinese remedy for "replenishing strength," preserving health and reducing fatigue. Due to the scarcity of wild material, a fermentation product from a specific mycelial strain (Cs-4, Paecilomyces hepiali) was developed. The authors assessed whether Cs-4 improves aerobic performance in healthy elderly people in a randomized double-blind placebo-controlled format.
Methods
Design — randomized double-blind placebo-controlled clinical trial. Population: 37 healthy elderly Chinese volunteers. Intervention: Cs-4 at 3 g/day in capsules or identical placebo capsules for 6 weeks. Performance testing before and after via cycle ergometry with a symptom-limited stepwise protocol. Endpoints: maximum oxygen uptake (VO₂max) measured by metabolic cart, and anaerobic threshold (VO₂θ) identified by two independent observers from VCO₂–VO₂ and VE/VO₂–time plots.
Results
After 6 weeks of Cs-4, VO₂max in the active group significantly increased from 1.88±0.13 to 2.00±0.14 L/min (p=0.050), and anaerobic threshold VO₂θ from 1.15±0.07 to 1.30±0.09 L/min (p=0.012). Neither measure changed in the placebo group. Adverse events are not reported in the annotation.
Conclusions
The authors conclude that the results confirm the Chinese notion that Cs-4 can improve oxygen uptake, aerobic capacity, respiratory function and fatigue resistance in elderly people under physical load.
Worth noting
A frequently cited work on VO₂max and aerobic power in the elderly, but it cannot be extrapolated without caveats. First, Cs-4 is cultivated Paecilomyces hepiali mycelium, not wild Cordyceps sinensis (Ophiocordyceps sinensis) from Tibet — the data apply to this specific commercial product (Jinshuibao) and do not transfer to any supplement labeled "Cordyceps." Second, the sample is very small (n=37) and apparently consisted only of ethnic Chinese volunteers; generalization to other populations requires caution. Third, the active group's VO₂max rose by ≈0.12 L/min at p=0.050 — a borderline value that might not survive multiplicity correction in other methodological contexts. Finally, the effect was shown over 6 weeks, and the annotation gives no data on persistence after discontinuation; nor are there clinically meaningful endpoints (subjective fatigue, tolerance of daily load, fall frequency) — only ergospirometric measures.