💪 Caffeine Pre-Workout Dose-Response Simulator

No Caffeine — The Unstimulated CNS Baseline

Every dose-response curve starts from a true zero-caffeine baseline.

• 85%: Habitual caffeine users (US) (consume it daily)
• ~5 h: Average adult half-life (range 1.5–9.5 h)
• Baseline: Resting CNS arousal (no adenosine blockade)
• Unblocked: Adenosine receptors (normal fatigue signaling)

Adenosine and natural fatigue signaling

Adenosine builds up and quietly signals the brain to feel tired.

Why baseline matters for the curve

Every performance gain later is measured against this resting line.

Individual variability before any dose

Genetics already shape baseline alertness before caffeine enters at all.

Low Dose (1–3 mg/kg) — Mild Stimulation Onset

A small dose nudges alertness up with barely any downside risk.

• 70–210 mg: Typical low dose (70 kg) (about one cup coffee)
• +2–5%: Performance boost range (endurance tasks)
• Mild gain: Reaction time change (small but measurable)
• Minimal: Side-effect risk (rare mild jitteriness)

Adenosine receptor blockade begins

Caffeine starts occupying adenosine receptors, delaying the fatigue signal slightly.

Early performance and alertness gains

Vigilance and simple reaction time improve first, before strength or power.

Why low doses feel safest

Blockade is partial, so overstimulation and anxiety symptoms stay very rare.

Moderate Dose (3–6 mg/kg) — The Effective Zone

This range delivers the strongest reliable performance-per-milligram payoff.

• 210–420 mg: Typical moderate dose (70 kg) (roughly 2–4 cups)
• +5–12%: Performance boost range (peak efficiency zone)
• 3–6: ISSN recommended range (mg per kg bodyweight)
• Strong: Alertness gain (consistent across studies)

Peak receptor occupancy and output

Most adenosine receptors are now blocked, maximizing the alertness payoff.

Endurance and strength performance gains

Time-to-exhaustion, power output, and perceived exertion all improve together.

Why sport science favors this range

Most benefit arrives here, before side effects start eating into it.

High Dose (6–9 mg/kg) — Diminishing Returns

Extra milligrams buy little extra performance but much more jitteriness.

• 420–630 mg: Typical high dose (70 kg) (exceeds daily guidance)
• +3–8%: Performance boost range (plateaus or dips)
• Elevated: Jitteriness/anxiety risk (common above 6 mg/kg)
• 400 mg/day: FDA single-dose caution (general healthy-adult limit)

The curve bends over, then falls

Near-total receptor saturation means extra dose adds risk, not benefit.

Overstimulation undermines fine motor control

Tremor, racing heart, and anxiety can actively hurt skilled performance.

Where the safety margin narrows

GI distress, insomnia, and palpitations become noticeably more common here.

Chronic Daily Use — The Curve Flattens and Shifts

Regular use blunts the same dose into a smaller, later effect.

• Upregulates: Adenosine receptor count (brain adds more receptors)
• 1–4 days: Tolerance onset (of consistent daily dosing)
• ~40–60%: Performance benefit retained (after weeks of daily use)
• 1–2 wk: Recommended reset period (abstinence restores sensitivity)

Receptor upregulation drives tolerance

The brain grows more adenosine receptors to compensate for constant blockade.

Same dose, smaller and later effect

The curve's peak drops and shifts right, needing more for less.

Cycling and resetting sensitivity

A short break restores much of the original dose-response curve.