Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| Caffeine (Anhydrous) | EAAs (Essential Amino Acids) | |
|---|---|---|
| Category | Training Compounds | Training Compounds |
| Standard Dose | 100-400mg daily (1-3mg/kg bodyweight for cognitive; 3-6mg/kg for athletic performance) | 6-12g per serving |
| Timing | 30-60 min before exercise or cognitive demand. Avoid within 8-10 hours of bedtime (half-life: 5-6 hours, but CYP1A2 polymorphisms cause wide variation). Morning preferred. | Intra-workout (sipped during training) or immediately post-workout. Can also be used between meals to maintain elevated MPS throughout the day. |
| Cycle Duration | ongoing with periodic tolerance resets (1-2 weeks off every 8-12 weeks) | ongoing during training periods |
| Evidence Level | strong_human | strong_human |
Caffeine is a methylxanthine that primarily acts as a competitive adenosine A1 and A2A receptor antagonist. By blocking adenosine's inhibitory effects on neural activity, caffeine increases alertness, reduces perceived exertion, and delays fatigue. Downstream effects include: increased dopamine, norepinephrine, and acetylcholine release; enhanced calcium release from sarcoplasmic reticulum (direct muscle contraction enhancement); increased fat oxidation via enhanced lipolysis (HSL activation through cAMP/PKA pathway from PDE inhibition); and central drive enhancement (reduced RPE). Caffeine also inhibits phosphodiesterase (PDE), raising intracellular cAMP.
100-400mg daily (1-3mg/kg bodyweight for cognitive; 3-6mg/kg for athletic performance)
30-60 min before exercise or cognitive demand. Avoid within 8-10 hours of bedtime (half-life: 5-6 hours, but CYP1A2 polymorphisms cause wide variation). Morning preferred.
ongoing with periodic tolerance resets (1-2 weeks off every 8-12 weeks)
The 9 essential amino acids (leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine) cannot be synthesized endogenously and must be consumed. Leucine is the primary mTORC1 activator (via Sestrin2 and CASTOR1 sensors), triggering p70S6K and 4E-BP1 phosphorylation to initiate muscle protein synthesis (MPS). The remaining EAAs are required as substrates for the actual protein synthesis — leucine signals the process, but all 9 EAAs must be present to complete it. EAA supplementation achieves comparable MPS stimulation to whey protein with fewer total calories.
6-12g per serving
Intra-workout (sipped during training) or immediately post-workout. Can also be used between meals to maintain elevated MPS throughout the day.
ongoing during training periods
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