Cyclists go faster with moderate caffeine dose, meta-analysis shows

Can caffeine make you faster? A new meta-analysis suggests, at least within the realm of a cycling time trial, the answer is yes. 

The new research was published yesterday in the Journal of the International Society of Sports Nutrition. It was the work of a group of researchers associated with universities and institutes in China and Australia. 

There is renewed interest in ergogenic sports aids in the runup to the Paris Olympic games. Caffeine is of interest as it has long been accepted as a sports nutrition and focus-enhancement ingredient that poses no doping concerns. 

Caffeine controversies 

Caffeine ingestion has long been considered safe, even at somewhat higher doses. A concern was raised back in 2012 when a teenager died after drinking two large Monster Energy beverages in relatively quick succession. The fact that the young woman was found during an autopsy to have suffered from an undiagnosed underlying medical condition did not forestall a U.S. Congressional hearing on the labeling and marketing of caffeinated energy drinks to underage consumers. The upshot of the affair was an IOM report in 2014 on the issue, which did not spark FDA action on new caffeine labeling regulations.  

And again in 2016, concerns were raised when pure powdered caffeine and concentrated liquid caffeine products began to become widely available on the internet. FDA banned the sale of those products, citing concerns that the powdered product in particular was so potent that a single teaspoon could constitute a lethal dose. 

Cycling time trials are of special interest among events in which a caffeine-fueled performance boost can be expected. The real-world event, so to speak, is very similar to the laboratory conditions of a cycling ergometer test. Cyclists traverse the course individually and must manage their energy expenditure and power output in the absence of the external motivation of rivals to chase. 

Studies winnowed down to a pertinent few 

The researchers combed through more than 1,700 studies and, after applying their exclusion criteria, they were left with 15 studies to include in their analysis. Exclusion criteria included studies conducted under extreme conditions (high heat or high altitude), studies that used caffeine gum instead of capsules or tablets as the delivery form because of different uptake profiles, studies that provided energy drinks during the tests, etc. 

The researchers were also looking specifically for studies that measured overall time in the time trial tests and mean power output as their endpoints.  

While all the studies were of small size (several studies included more than one trial), the overall number of subjects included in the meta-analysis came to more than 220. 

The included studies used a range of dosages, from 1 milligram per kilogram of body weight up to a high of 6 mg/kg. For a 72 kg (158 pound) racing cyclist, those caffeine doses would equate to a range of 72 mg up to 432 mg. 

Small effect sizes add up to big results 

The authors said the expected effect sizes were quite small but were nevertheless significant. Cutting the time needed to complete a given time trial circuit by as little as 2% could be the difference between finishing in the top 10 or getting a spot on the podium, they noted. The men’s and women’s time trial course in Paris is 32.4 km, a distance the men’s winner could be expected to cover in about 37 minutes. 

The authors concluded that a moderate dose of caffeine, in the 4-6 mg/kg range (288-432 mg), was optimal. That provided a significant performance boost over the lower range, which showed little effect. 

“This systematic review and meta-analysis showed that a moderate dosage (4–6 mg/kg) of caffeine, identified as the optimal dose range, significantly improves the time trial performance of cyclists. Contrastingly, a low dose (1–3 mg/kg) does not yield the same improvement. These findings could provide a basis for cyclists and coaches to devise more effective caffeine supplementation strategies,” they noted. 

Individual differences 

A big caveat, however, is that caffeine absorption is different among different people due to genetic factors. A trainer would need to gather data on an individual cyclist before devising an optimal supplementation strategy, the authors counseled. 

“When tailoring personalized supplement regimens, it is essential to consider individual athlete differences (i.e. gender, dietary habits, and genetic types) to maximize caffeine’s ergogenic effects,” they concluded.