Chen S., Li Z., Krochmal R., Abrazado M., Kim W., Cooper C.B. Effect of Cs-4 (Cordyceps sinensis) on exercise performance in healthy older subjects: a double-blind, placebo-controlled trial. Journal of Alternative and Complementary Medicine. 2010;16(5):585–590.
Rationale
Cordyceps sinensis has long been used in traditional Chinese medicine as an "adaptogen" for fatigue. A standardized preparation, Cs-4, is made from fermented mycelium and is registered as a medicine in China. Data on healthy elderly people's aerobic measures were scarce before this work; previous studies concerned animals or patients with chronic disease.
Methods
A randomized double-blind placebo-controlled prospective pilot study (UCLA, USA). Included 20 healthy non-smoking volunteers aged 50–75 leading ordinary lives, not taking supplements. Participants were randomized to Cs-4 (333 mg × 3 times daily, ≈1 g/day total) or placebo for 12 weeks. Primary outcomes: metabolic (lactic-acid) threshold and ventilatory threshold on a cycle ergometer with breath-by-breath analysis. Secondary: VO2max, gas-exchange measures, exercise tolerance.
Results
All 20 participants completed the protocol. In the Cs-4 group the metabolic threshold (the point above which lactate begins accumulating) rose 10.5% — from 0.83 ± 0.06 to 0.93 ± 0.08 L/min (p < 0.02). The ventilatory threshold (the point where unbuffered H+ stimulates ventilation) rose 8.5% — from 1.25 ± 0.11 to 1.36 ± 0.15 L/min (p < 0.05). The placebo group showed no significant changes. VO2max changed in neither group. No adverse events were recorded.
Conclusions
A 12-week Cs-4 course in healthy elderly people significantly improves metabolic and ventilatory thresholds without affecting maximum oxygen uptake. The authors interpret the effect as "economization" of aerobic work: the same workloads can be performed with a smaller anaerobic contribution. This is the first such effect documented in a western population for Cs-4 in supplement form.
Worth noting
The main methodological limitation is the small sample (n=20), typical of pilot studies; at n=10 per arm individual variation is hard to exclude. Still, the metabolic-threshold effect (+10.5%) is clinically meaningful, comparable to the effect of 8 weeks of moderate-intensity aerobic training in the elderly. The absence of VO2max change fits the "economization, not peak power" hypothesis and agrees with other work (Xiao 2004 on VO2max, Park 2017 on anaerobic threshold). This distinguishes Cs-4's effect from classical ergogenic aids (caffeine, creatine), which typically affect peak power.