Summary
Eric Trexler from Stronger by Science talks about how he's handled the identity crisis of not training during quarantine, drawing on Buddhist philosophy about the impermanence of self. The conversation shifts into practical territory with caffeine -- how it works, optimal dosing, tolerance management, and why it remains one of the most reliable performance supplements available.
Key Points
- Caffeine improves both strength and endurance performance by blocking adenosine receptors, reducing perceived effort, and increasing pain tolerance.
- Optimal caffeine dose for performance is 3-6 mg per kg of bodyweight, taken 30-60 minutes before training.
- Caffeine tolerance builds within 1-2 weeks of daily use; cycling off for 7-10 days fully restores sensitivity.
- Low doses (1-2 mg/kg) still provide cognitive and mood benefits even in habitual users, making caffeine useful for focus on non-training days.
- Avoid caffeine after 2pm (or 8+ hours before bed) to prevent disruption of slow-wave sleep, even if you feel you fall asleep fine.
- Your identity is not fixed: periods without training (like quarantine) are opportunities to explore who you are beyond your gym routine.
Key Moments
Caffeine is a solid B-tier supplement for all training types
Eric Trexler explains that caffeine benefits endurance, strength, and power performance across a large body of research. It is essentially as effective as anything that is not creatine.
"Caffeines are really special supplement in the sense that its effects are pretty positive across the board."
Effective caffeine dosing requires at least 3mg per kilogram
The research-backed caffeine dose for performance benefits is 3 to 6 milligrams per kilogram of body mass, which translates to roughly 300mg or more, significantly higher than a typical cup of coffee.
"The dosage range for performance benefits is usually between three to six milligrams per kilogram of body mass, which is actually quite high."
Caffeine genetics affect anxiety but not performance benefits
Trexler explains that regardless of CYP1A2 or ADORA2A genotype, everyone can get performance-enhancing effects from caffeine. However, certain genotypes may experience exaggerated anxiety side effects from large doses.
"The most up-to-date research indicates no matter what you've got in terms of the CYP 1A2 gene or the adora2a gene, you can get a performance enhancing effect from caffeine."
Caffeine timing and dosing comes down to common sense
After deep-diving into caffeine research, Trexler concludes that practical advice boils down to common sense: if you feel terrible after your dose, take less, and if you sleep poorly, consume it earlier in the day.
"As someone who's been into the deepest depths of the caffeine research, I'd like to say I come out with something more valuable in common sense, but, you know, there's some little interesting tidbits here and there."
