It's 4:47am on race morning. The coffee in the host hotel lobby is burnt. My wetsuit is half-on. And I'm doing math in my head: 70 kilos, 3 milligrams per kilo, that's 210mg, which is two cups of coffee I'm not going to drink because the last time I did that before an Ironman I spent the first 20 minutes of the swim worried about something other than swimming.
This is the post I wish I'd had when I started racing.
I'm Rodrigo. I'm the founder of Drizz, and I'm a triathlete — sprint, Olympic, and 70.3, with two full Ironman finishes and two DNFs that taught me more than the finishes did. Both DNFs ended the same way: throwing up at mile 18 of the run because my gut had given up on me three hours earlier. Caffeine was part of the problem. It's also now part of the solution.
Direct answer: how much caffeine should a triathlete actually take?
The consensus from the International Society of Sports Nutrition and the American College of Sports Medicine is 3–6 mg of caffeine per kilogram of body weight, taken roughly 30–60 minutes before the start of performance, with the option to redose during long events.
For most triathletes that translates to:
- Sprint / Olympic (under 3 hours): one dose, 3–4 mg/kg, 45 minutes pre-race.
- Half Ironman / 70.3 (4–6 hours): initial dose pre-race, optional second dose at T2 before the run.
- Full Ironman (9–14+ hours): split into 3 doses — pre-race, T1, T2 — staying at the lower end of the range each time so total intake stays under ~6 mg/kg.
The scariest mistake is loading the front end with 400mg of caffeine and a pre-race espresso "for good measure." That's how you end up surveying every porta-potty on the course.
The rest of this post is what I've learned actually executing this plan over the last six years of racing. It's also why I built Drizz Energy Drops the way I did — because every off-the-shelf option for race-day caffeine had a problem I needed to solve.
Table of contents
- Why caffeine works for endurance — the actual mechanism
- The pre-race dose: timing, food, and the bathroom math
- T1 and T2: where most triathletes get it wrong
- Why drops beat gels for long-course racing
- GI distress: the unsexy reason most Ironmans end early
- Sprint vs Olympic vs 70.3 vs Ironman: dose templates
- What I actually carry in transition
Why caffeine works for endurance — the actual mechanism
Caffeine is one of the most-studied legal performance aids in sport. It works through a few pathways simultaneously: it blocks adenosine receptors (so you perceive less fatigue), it increases the release of catecholamines like adrenaline, and there's published research in the Journal of Applied Physiology suggesting it may improve neuromuscular performance and reduce perceived exertion in the back half of long events.
Translation for race day: caffeine doesn't make you faster. It makes hard feel less hard. In a 12-hour Ironman, that's the difference between a 4:30 marathon split and a 5:15 marathon split.
The other thing worth knowing — caffeine was removed from the WADA prohibited list in 2004. It's currently on the monitoring program but not banned. USA Triathlon and Ironman follow WADA. You can race on caffeine without issue.
The pre-race dose: timing, food, and the bathroom math
Here's where I see new triathletes mess up. They've read that caffeine peaks in blood plasma around 45–60 minutes after ingestion, so they take their dose at 5am for a 6:30am start. Then they eat their oatmeal, drink 24oz of water, drink another coffee out of nerves, and by the time the cannon fires they've had 350mg of caffeine and are in line for a porta-potty 12 deep.
My rule: one caffeine source, one time, 45 minutes out. Not two. Not three.
For a 70kg athlete, 3 mg/kg = 210mg. That's roughly:
- 2 squeezes of green tea caffeine drops (130mg)
- Plus the residual caffeine from one normal cup of morning coffee (~95mg)
- Total: ~225mg, hitting peak right around the gun
If you're sensitive to caffeine, start at 2 mg/kg and build from there in training. The cardinal rule of triathlon nutrition — and I cannot say this loud enough — is nothing new on race day. Test every dose, every form, every timing combination in training first.
T1 and T2: where most triathletes get it wrong
For sprint and Olympic distance, you dose once and you're done. For 70.3 and full Ironman, the math changes because caffeine has a half-life of roughly 5 hours according to the Mayo Clinic. Your pre-race dose is fading by the time you hit T2 of an Ironman.
Here's what works for me at 70kg:
T1 (swim → bike, ~1:05 into the race): I leave a small flask in my T1 bag. One squeeze (65mg) of green tea caffeine drops into a 750ml bottle of plain water on the bike. Sip over the first hour of riding. No sugar load — the carbs are coming from my bike nutrition separately.
T2 (bike → run, ~6:30 into a full Ironman): This is the make-or-break dose. One more squeeze, this time straight into a small handheld flask of water that I carry for the first 5 miles of the run. After that I'm on course nutrition.
The reason I split it: a single 200mg hit at hour 6 doesn't give you anything. You're already past peak from the morning dose, your gut is compromised, and dumping that volume of liquid in is asking for trouble. Spacing the caffeine across transitions keeps blood plasma levels in the sweet spot from start to finish.
Why drops beat gels for long-course racing
I'll be honest about why I built Drizz the way I did. Caffeinated gels have two problems for triathletes:
- They're a sugar bomb. A standard caffeinated gel has ~25g of carbs plus the caffeine. By hour 7 of an Ironman, you've already absorbed 60g/hour of carbs from your other fueling. Adding more concentrated fructose to a gut that's running on 20% of normal blood flow is how you end up at mile 18 like I did.
- The dose is locked. A gel has whatever the manufacturer put in it — usually 50mg or 100mg. You can't take 30mg. You can't take 130mg. You take their dose or you don't.
Drops solve both. 65mg per squeeze means I can do 1, 2, or 3 squeezes depending on how the day is going. Zero sugar means the caffeine isn't packaged with carbs my gut doesn't want anymore. And a 60ml bottle weighs nothing in a transition bag.
I'm not saying gels are bad. Gels are tools, and they work great for some people and some races. But for the caffeine portion of my race plan specifically, separating caffeine from carbs has been the single biggest GI improvement I've made.
For the broader nutrition picture and how athletes from other disciplines time their caffeine, I've written about pre-workout dosing in more detail here.
GI distress: the unsexy reason most Ironmans end early
Research published in Sports Medicine found that 30–50% of endurance athletes experience GI symptoms during long-course racing. The mechanism is well understood: during sustained high-intensity exercise, blood is shunted from the gut to working muscles. Gastric emptying slows. Anything sitting in your stomach — gels, sports drinks, that pre-race banana — ferments.
Caffeine itself can be a contributor. It increases gastric acid secretion and, in some people, acts as a mild laxative. Combine it with the high-carb concentration of gels and you've stacked the deck against your gut.
What's worked for me:
- Lower total caffeine. I used to chase 6 mg/kg. Now I sit at 3–4 mg/kg total across the day.
- Separate caffeine from carbs. Drops in plain water for the caffeine. Gels and bars on a separate clock for the calories.
- Smaller volumes more often. Better to sip 100ml every 15 minutes than dump 500ml at once.
- Practice it. Every long ride and every long run is a nutrition rehearsal. I know exactly how my gut responds to my plan because I've tested it 50 times.
This isn't medical advice. If you're getting GI distress in training, talk to a sports dietitian. They'll save you years of guessing.
Sprint vs Olympic vs 70.3 vs Ironman: dose templates
Here's how I break it down for a 70kg / 154lb athlete. Scale up or down for your weight at 3–4 mg/kg total.
Sprint (under 1:30):
- Pre-race: 200mg, 45 min out
- In-race: nothing
- Total: 200mg
Olympic (2:00–3:00):
- Pre-race: 200mg, 45 min out
- T2 (optional): 65mg
- Total: 200–265mg
70.3 / Half Ironman (4:00–6:00):
- Pre-race: 130–200mg, 45 min out
- T1: 65mg in bike bottle
- T2: 65mg in run handheld
- Total: 260–330mg
Full Ironman (9:00–14:00):
- Pre-race: 130mg, 45 min out (lower than you'd think — long day ahead)
- T1: 65mg
- Mid-bike (~hour 4): 65mg
- T2: 65mg
- Mid-run (~mile 13, optional): 65mg
- Total: 260–390mg, spread across 12 hours
Again — these are templates from my own racing and conversations with my training partners. Not prescriptions. Your body, your training, your race.
What I actually carry in transition
For full transparency, here's my current Ironman setup:
- Pre-race: 1 Drizz Energy Drops bottle in my morning bag, 2 squeezes into a 16oz water bottle 45 minutes before the gun.
- T1 bag: Travel-size flask of water with 1 pre-mixed squeeze, taped to my bike bottle.
- Bike special needs: Backup bottle with 1 squeeze pre-mixed, in case the first goes overboard on a rough road.
- T2 bag: Handheld with 1 squeeze pre-mixed, swapped for course cups after mile 5 of the run.
The whole caffeine plan fits in one 60ml bottle that lives in my transition bag for the entire weekend. It's TSA-legal carry-on, which matters when I'm flying to Kona or to a destination 70.3.
That's the plan. It's not magic. It's not a secret. It's just what's worked for me after enough mistakes that I started tracking them.
If you're a triathlete who wants to dial in caffeine without the sugar crash, start with the protocol above and a single bottle. Test it on long training days. Tweak until it's yours.
What would your race-day plan look like if you stopped guessing?
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