From the Desk of a Doctor Newsletter
☕🔄 The Caffeine Reset: Why Your Daily Habit May Be Weakening Its Performance Boost
Caffeine is one of the most reliable ways to improve workout performance.
It can help you run faster, push harder, and produce more power.
But here’s the twist:
Taking it every day may make it less effective.
A new randomized controlled trial (PMID: 39905628) found that daily caffeine use reduced its performance-enhancing effects — but taking 11 days off restored them.
In other words: your body adapts.
The Study
Researchers followed 73 young men who normally consumed very little caffeine.
They were split into four groups:
• Caffeine only
• Caffeine + high-intensity training
• Placebo only
• Placebo + training
The caffeine dose was 3 mg per kilogram of body weight daily (roughly 200–250 mg for many adults) for 8 weeks.
Performance was tested using:
• 🏃♂️ A 3-km endurance run
• 🚴 A Wingate sprint test (short, max-effort cycling)
Testing happened multiple times during the 8 weeks — and again after an 11-day caffeine break.
The Findings 📉
• ⚡ Caffeine improved performance overall
• 📉 But the improvement was smaller in people taking caffeine daily
• ⬆️ Increasing the dose restored performance — but only in trained individuals
• 🔄 After 11 days off caffeine, the performance boost returned fully in everyone
That suggests daily use created tolerance — and short-term withdrawal reversed it.
Why This Matters
Caffeine works by blocking adenosine — a chemical that makes you feel tired.
With regular exposure, your body adjusts. It can increase adenosine receptors, which may reduce how strong caffeine feels over time.
So while caffeine still works, the “edge” may fade with constant use.
Interestingly, a large meta-analysis of 60 randomized trials (PMID: 35536449) did not find consistent evidence of this tolerance effect — so the science isn’t completely settled.
But this new study suggests something important:
Using caffeine strategically may be more powerful than using it constantly.
Takeaway
If you rely on caffeine every day for workouts, you may be getting less of a boost than you think.
Taking about 10–11 days off could reset your sensitivity and restore its full performance benefit.
Sometimes less is more.
— Dr. Myro Figura, M.D.
Read the study:
https://pubmed.ncbi.nlm.nih.gov/39905628/
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About the Author
I’m Dr. Myro, a board-certified doctor and med school educator who somehow ended up with over 6 million followers watching my science videos on
YouTube,
Instagram,
TikTok,
and Facebook.
I’ve published 60+ scientific abstracts and even written a book, but this newsletter is my favorite project. Here I get to share the good stuff — simple, actionable health tips delivered twice a week. Happy to have you here.
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