From Half Marathons to 100-Milers: Mastering the Art (and Science) of Caffeine

I don't know about you, but I am not ashamed to admit I need coffee to start the day off right!

Caffeine is one of the most well-researched, effective, and widely used performance enhancers in endurance sports. Whether you're running a half marathon or tackling an ultra race, how and when you use caffeine can significantly impact your performance.

This newsletter will break down:

• What the research says about caffeine and endurance performance
• Guidelines for timing and dosing
• Race strategies
• A cheat sheet of common items and their caffeine content

The Science Behind Caffeine for Endurance Athletes

Caffeine has been shown to:

• Decrease perceived exertion
• Increase alertness and focus
• Improve endurance performance by mobilizing fat stores and sparing glycogen

To get the most out of your morning coffee, it takes more than just sipping it before your run. Timing and dosage matter.

Recommended Dosage:

• 3-6 mg/kg of body weight taken before exercise can improve performance.
  • Perspective: for a 150 lb athlete (~68 kg), this equates to ~200-400 mg of caffeine.
• Ingest 30-60 minutes before an event (SEE MORE ABOUT THIS BELOW).
  • If needed, 1-2mg/kg of body weight every 2-4 hours throughout an event to “re-dose”.
• 9mg/kg of body weight is the recommended maximum amount of caffeine in one day.

Timing Matters:

• Fasted state: Peak caffeine absorption is ~60 minutes after ingestion
• Fed state: Peak absorption can be delayed to around ~3 hours

Race Day Example: The 4-5 Hour Marathoner

Let’s say you weigh 150 lbs (68 kg) and you take ~300 mg of caffeine (4.5 mg/kg, the sweet spot between 3 and 6 mg) about an hour before your race. Because you’ve eaten beforehand, your caffeine will likely peak just as the race starts, or shortly after.

To sustain energy, consider this plan:

• Pre-race (1 hr prior): 300 mg caffeine (~4.5 mg/kg)
• 2 hours in: Re-dose with ~100 mg (1.5 mg/kg)
• 4 hours in: Another 100 mg

This keeps your total dose around 7 mg/kg for the day, below the 9 mg/kg daily threshold for most athletes.

Race Day Example: The 100-Mile Ultramarathoner (24+ Hour Finish)

In ultra-distance events, especially overnight, caffeine becomes a crucial tool for maintaining mental alertness. Starting with a lower initial dose allows for more strategic dosing later in the race when fatigue peaks. Below is another example for a 150 lb runner.

Sample Strategy:

• Pre-race: Low dose, 100-150 mg (around 1.5-2 mg/kg) to stay sharp but conserve potency. Starting on the lower end allows you to fuel more consistently throughout the event.
• Every 2-4, or even up to 6 hours: Re-dose with 68-135 mg (1-2 mg/kg)
• Late race or overnight (18+ hrs): Use small 50-100 mg doses for alertness

Even if you reach 10-12 mg/kg over 24+ hours, it’s still spaced out enough to remain safe for most runners.

Starting with a low dose helps maintain alertness and rhythm without using up your total "caffeine budget." Save the bigger doses for when mental fatigue sets in.

Bonus: Some runners taper off caffeine in the weeks before a race to become more sensitive to its effects on race day.

Final Thoughts:

Don’t test this strategy for the first time on race day, practice first!

Chances are, you’re already consuming caffeine in some form before your runs. So, start by taking stock:

• How much are you actually drinking?
• When are you drinking it?
  - Are you chugging a cup on your way out the door?
  - Or are you sipping first thing in the morning but not running until after school drop-off and errands?
• Are you reaching for caffeinated gels at random points in your run without much thought?

If so, it’s time to add some intention to your routine. Start by dialing in what you’re already doing, then layer in additional strategy where needed. Small tweaks may make a big difference in how caffeine supports your performance.

Quick Reference: Popular Caffeinated Products

GU Energy Gels: 35-70 mg
Clif Blocks: 50 mg
Maurten Caf 100 Gel: 100 mg
Nuun Energy Tablet: 80 mg
8oz Coffee: 90-120 mg
Caffeine Gum: 50 mg
Caffeine Pill: 100-200 mg
12oz Coca-Cola: 34 mg
12oz Coca-Cola Energy: 114 mg
Bang Energy Drink: 300 mg

If you are interested in using caffeine to boost your performance, physically and mentally, use this as a guide to spread your intake across the race in 1-2 mg/kg increments.

Sis, if you are reading this, maybe you can bring me a shot of espresso at the 18-mile mark this weekend 😉

Bottom Line:

Caffeine can boost performance in endurance events from half marathons to 100+ milers, but timing, dose, and context matter. Use it with intention, train with it, and learn how your body responds.

Now I want some coffee!

-Adria