For endurance performers, the Holy Grail in nutritional terms would be a food or supplement that somehow managed to boost oxygen uptake and thence energy production. Claims like these have been made on behalf of two herbal supplements traditionally used in Chinese and Ayurvedic medicine – cordyceps sinensis and rhodiola rosea.
Indeed, the first of these gained world attention in 1993 following the success of Chinese female runners, who achieved records in 1,500m, 3,000m and 10,000m events and attributed their success to a cordyceps-rich diet.
Were they deluding themselves? That’s the question a team of US researchers set out to answer with a study of the effects on oxygen uptake in 17 amateur competitive cyclists of a commercial formula containing cordyceps and rhodiola as its primary ingredients.
The subjects, all male, performed a staged cycling test to exhaustion before and after a 14-day period of supplementation with either the active ‘adaptogen formula’ or a matched placebo. During the cycling tests, they were monitored for a range of performance variables, including peak oxygen uptake, power output, heart rate and time to exhaustion.
The result? The researchers did not observe any statistically significant difference between or within treatment groups for any of these variables. ‘Therefore,’ they say, ‘it appears that this commercial product confers no ergogenic effect when ingested over a 14-day treatment period.’
They acknowledge a number of limitations with their study: firstly, they did not have the product independently analysed; secondly, they were unaware of the precise quantities of the active ingredients present in the supplement; thirdly, and perhaps most crucially, it was possible that they did not allow the cyclists to ingest the product for long enough to exert an ergogenic effect, even though they were following the manufacturer’s recommendations.
‘Whether this formula will prove to have a benefit to exercise when ingested over longer periods has yet to be determined,’ they conclude.
Med Sci Sports Exerc, vol 36, no 3, pp504-509, 2004
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