Taking caffeine before exercise may make the experience more enjoyable, but it does not cause muscles to grow larger or stronger over time.
Evidence from Studies
Supporting (2)
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Six weeks of caffeine supplementation enhances muscle thickness without augmenting strength gains—a randomized controlled trial
The study found that taking caffeine made muscles grow a bit bigger, but didn’t make people stronger. This contradicts the claim that caffeine doesn’t help muscles grow.
Caffeinated chewing gum produces comparable strength and power gains to capsules with fewer side effects in resistance-trained men
This study found that caffeine, whether chewed in gum or swallowed in a pill, helped people lift heavier weights and generate more power during exercise. That means caffeine does help with strength, which contradicts the claim that it doesn't.
Contradicting (2)
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Are Caffeine’s Effects on Resistance Exercise and Jumping Performance Moderated by Training Status?
This study found that caffeine helped people lift more weight and do more reps in the short term, which contradicts the claim that caffeine doesn’t improve strength. It didn’t measure how much people enjoyed working out or long-term muscle growth.
This study found that people who took caffeine before working out got stronger than those who didn’t, which goes against the claim that caffeine doesn’t help with strength. It didn’t study whether people enjoyed exercise more, but it did prove caffeine helps build strength.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.