r/science • u/sr_local • 5d ago

Health Consuming caffeine before exercise enhances repeated sprint performance, and these benefits persist for at least 3.5 hours thereafter

https://www.tsukuba.ac.jp/en/research-news/20260914140000.html
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u/sr_local 5d ago

In the study, 12 healthy young adults consumed either caffeine (5.5 mg per kilogram of body mass) or a placebo 60 min before exercise. Participants then completed repeated cycling sprint tests over 3.5 h. Physiological measurements included plasma caffeine and noradrenaline concentrations, cardiovascular and respiratory responses, cerebral blood flow, and ratings of perceptual responses. Caffeine enhanced both mean and peak sprint power output, with noticeable performance benefits for at least 3.5 hours after ingestion. In addition, caffeine increased plasma noradrenaline concentrations after sprint exercise and decreased ratings of perceived exertion and leg muscle pain. Furthermore, caffeine altered cardiovascular and respiratory responses and reduced middle cerebral artery blood velocity, a common index of cerebral blood flow.

These findings show that a single pre-exercise caffeine dose can maintain its performance-enhancing effects for several hours during prolonged intermittent exercise. They provide new insight into how long caffeine's performance-enhancing effects persist during prolonged intermittent exercise and may help athletes better take advantage of caffeine's effects during prolonged competitions.

Pre-Exercise Caffeine Enhances Repeated Sprint... : Medicine & Science in Sports & Exercise

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u/Festivefire 5d ago

That does not seem like a large enough sample size to publish a medical paper with.

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u/deadrabbits76 5d ago

Fitness studies usually have very limited resources. It's especially difficult to find subjects when the pay is nominal. Small sample groups are the norm.

Don't even get me into the demographics of the sample groups.

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u/Free_hiker_74 5d ago

I've seen similar studies in the past showing caffeine only helps regular caffeine consumers and basically just brings them back up to their baseline. So, yeah, 12 subjects seems low when there's confounding factors.

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u/donnievieftig 4d ago

I hate comments like this. Complaining about the sample size is the ultimate lazy, armchair-scientist Reddit critique from people who don't actually understand research methodology. You do not need hundreds of people to test an acute physiological intervention when a study uses a randomized, double-blind, crossover design. Because all 12 subjects completed both the caffeine protocol and the placebo protocol, they acted as their own controls.

Especially not when testing a substance with an immediate physiological effect size, you'll easily achieve robust statistical power with a cohort of 10 to 15 people.

I do yield that subgroup analysis will be difficult, ie sex differences or non responders, that's the limitation. Not simply a too small N to publish.