Caffeine
Adenosine receptor antagonist. The most consumed psychoactive substance worldwide. Well-established ergogenic aid.
Evidence by Outcome
Alertness
Significant improvement in reaction time and vigilance
Endurance Performance
2-4% improvement in time-trial performance
Strength
3-5% increase in 1RM
Fat Oxidation
10-30% increase in fat oxidation rate
Cognition
Improved attention, working memory, reaction time
Dosing Guide
100-200mg
4 mg/kg
30-60 min before desired effect. Avoid within 8-10h of sleep.
CYP1A2 genetics affect metabolism speed (fast vs slow metabolizers). Tolerance develops; consider cycling.
Safety Profile
Possible Side Effects
- • Anxiety
- • Insomnia
- • Increased heart rate
- • GI discomfort
- • Dependence
Contraindications
- ⚠ Anxiety disorders
- ⚠ Cardiac arrhythmias
- ⚠ Pregnancy (limit 200mg/day)
Known Interactions
L-Theanine smooths caffeine's jitteriness while preserving alertness. 1:2 ratio optimal.
Source: Nutritional Neuroscience, 2008
Early studies suggested caffeine blunts creatine's ergogenic effect, but more recent evidence is mixed. Likely fine for most people.
Source: J Int Soc Sports Nutr, 2017
Caffeine increases magnesium excretion. Heavy coffee drinkers (>3 cups/day) may need higher magnesium intake.
Source: Magnesium Research, 2011
Ashwagandha reduces cortisol while caffeine raises it. May partially counteract each other's effects. Consider timing: ashwagandha PM, caffeine AM.
Source: Pharmacological reasoning
If concerned about interaction, separate by 1-2 hours. Take creatine at a different time of day than your coffee.
Source: Practical recommendation
Classic energy drink combination. Taurine may attenuate caffeine's cardiovascular effects while preserving cognitive benefits.
Source: Amino Acids, 2014