Sweatr blog
The science behind performing on race day
Guides, deep-dives, and practical advice for runners, cyclists, and triathletes who want to get their fueling right.
How much should you drink during a marathon?
The generic answer is 500ml per hour. The right answer is calculated from your body weight, sweat rate, and how hard you're actually working. Here's how to find your number.
How to Adjust Your Fueling Plan When Race Day Is Hotter Than You Trained For
A step-by-step guide to adjusting your hydration, sodium, and carb plan when race-day heat catches you off guard.
How to Predict Your Race-Day Sweat Loss from Training Data
Use your watch data and training logs to estimate how much you'll sweat on race day — before you even get to the start line.
Dehydrated or Overhydrated? How to Read the Signs Mid-Race
Learn to tell the difference between dehydration and overhydration during a race — and what to do before either one ruins your day.
Caffeine in Your Racing Gels: How Much Helps, When to Take It, and When to Skip It
A practical guide to caffeine dosing and timing in racing gels so you get the boost without the gut bomb.
Sleep Tracking on Apple Watch vs Garmin: What Runners Should Actually Look At
Your watch tracks your sleep, but which metrics matter for running performance and recovery?
How to Find Your Personal Carb Ceiling — Why 90g Per Hour Isn't Right for Everyone
The 60-90g carb advice is too vague. Here's how to find the number that actually works for your body, pace, and race distance.
Your Hydration Plan Worked in April — Here's Why It Fails When Summer Hits
Rising temps change everything about your sweat rate and sodium needs. Here's how to adapt before your next long run.
How Much Should You Drink During a Half Marathon?
A personalised guide to half marathon hydration based on your sweat rate, pace, and race-day conditions.
Do You Even Need Gels for a Half Marathon?
A first-timer's honest guide to whether you need gels, how many, and when to take them during your half marathon.
Sweat Sensors vs Smartwatches: Do You Need Extra Hardware for Personalised Hydration?
Nix, hDrop, and FLOWBIO promise real-time sweat data. Here's what your Garmin or Apple Watch already tells you — and where the gaps are.
Hydrogels, Isotonic Gels, and Traditional Gels: Which One Should You Race With?
A science-backed comparison of the three main gel types to help you pick the right fuel for your next race.
Fueling a 3-Hour vs 5-Hour Marathon: Why One Plan Doesn't Fit All
A 5-hour marathoner needs a completely different fueling strategy than a 3-hour runner. Here's exactly how pace changes everything.
Every Sodium Guide Gives You a Range. Here's How to Find YOUR Number.
Stop guessing between 300mg and 1500mg per hour. Here's how to find your personal sodium needs for running and racing.
How to Build Your Race-Day Fueling Kit: What to Carry, Where to Stash It, and When to Use Each Item
A practical guide to carrying gels, electrolytes, and fluids during a marathon or half marathon — so your fueling plan actually works on race day.
VO2 Max on Your Watch: What It Actually Means and Whether You Should Trust It
Your watch shows a VO2 max number every week. Here's what it's really measuring and when to ignore it.
The 12-Week Race Nutrition Timeline: What to Focus On Each Phase
A week-by-week nutrition countdown for your marathon — from gut training to race morning.
The 16-Week Fall Marathon Nutrition Timeline
A phase-by-phase nutrition plan from sign-up to start line for your fall marathon.
How to Train Your Gut to Handle 90g of Carbs Per Hour
A 12-week protocol to build carb tolerance for race day so you can fuel harder without GI distress.
How to Pick the Right Gels and Electrolytes for Your Race
A practical framework for choosing race-day gels and electrolytes based on your body, your distance, and your data.
What to Do When Your Stomach Turns Mid-Race
A runner's rescue plan for GI distress during a marathon, plus how to prevent it with personalised fueling.
Sodium Loading Before a Marathon: How Much You Need and When to Start
Pre-race sodium loading boosts plasma volume and cuts cramping risk. Here's the exact protocol for the 48 hours before your marathon.
115 Grams Per Hour: What Sawe's Sub-2 Marathon Teaches You About Fueling
Sawe fueled his 1:59 marathon on 115g carbs/hour. Here's what his protocol reveals about building your own race-day fueling plan.
Your Sweat Rate Isn't Fixed: How Fitness, Heat, and Humidity Change Everything
Sweat rate shifts with fitness, weather, and acclimatisation. Here's what changes, why it matters, and how to adjust.
Garmin Now Tracks Your Food — Here's What It Still Can't Tell You
Garmin Connect+ logs calories and macros. It still won't build you a fueling plan. Here's the gap — and how to close it.
Real Food vs Gels: What Should You Actually Fuel With on Race Day?
Gels aren't the only option. Here's how to choose between real food and gels based on your pace, distance, and stomach.
The 3 Biggest Nutrition Mistakes Runners Make in the Final 3 Weeks Before a Marathon
Most marathoners sabotage race day before the gun fires. Avoid these three taper-phase nutrition mistakes.
Apple Watch Heart Rate Zones: Are They Accurate Enough to Build a Fueling Plan?
Your Apple Watch heart rate zones shape your pacing — but can they guide your nutrition? Here's what the data actually tells you.
You Can Drink Too Much During a Marathon — Here's How to Stay in the Safe Zone
Overhydration hospitalises runners every year. Learn how to find your personal fluid ceiling and avoid hyponatremia on race day.
How to Fuel a Half Marathon: The Complete Plan by Finishing Time
Your half marathon fueling plan depends on your pace, not generic advice. Here's exactly what to eat and drink by finishing time.
Your Watch Tracks Everything Except What to Eat: How to Turn Wearable Data Into a Race-Day Fueling Plan
Your Garmin or Apple Watch collects training data all day. Here's how to turn those metrics into a fueling plan you can actually follow on race day.
You Bonked at Mile 22 Despite a Fueling Plan — Here's What Went Wrong
Had a fueling plan and still hit the wall? These five mistakes explain why — and how to fix them before your next race.
How to Practise Your Race-Day Nutrition During Long Runs
Stop winging it on race day. Here's an 8-week protocol for testing your fueling plan in training.
Why Your Watch's Sweat Loss Estimate Is Probably Wrong — And What to Do Instead
Garmin and Samsung sweat-loss numbers can be off by 700ml. Here's why, and how to get a number you can trust.
What to Eat After a Marathon: A Recovery Timeline From Finish Line to the Next Morning
Hour-by-hour recovery nutrition after a marathon — what to eat at 0–30 min, 2 hours, dinner, and breakfast, personalised by effort.
Drink to Thirst or Follow a Plan? Warm-Weather Marathon Hydration Without the Cramp or the Hospital
How to avoid both cramping and hyponatremia when race day is hotter than you trained in — the middle path between drink-to-thirst and a rigid plan.
Why Your Energy Gels Make You Feel Sick — And How to Fix It
Gel nausea isn't about the brand. It's about timing, carb load, and a gut that hasn't been trained. Here's the science and the fix.
HRV, Body Battery, Training Load: How to Actually Fuel Off Your Garmin Data
Your Garmin shows HRV, Body Battery, and Training Load every morning. Here's what each one should change about what you drink and eat that day.
Electrolytes for Runners: Which Ones Actually Matter and How Much You Need
Sodium, potassium, magnesium — here's what each one does during a run, how much you lose in sweat, and how to stop guessing your dosage.
What to Eat the Morning of a Marathon: A 4-Hour Countdown from Alarm to Start Line
A minute-by-minute race morning fueling plan — what to eat, when, and how much — so you hit the start line fuelled without a stomach full of regret.
How to Calculate Your Personal Sweat Rate (and Why Generic Hydration Advice Is Failing You)
Your sweat rate is unique. Here's how to measure it at home and turn it into a hydration plan that actually works on race day.
Carb Loading for Your Spring Marathon: A 3-Day Plan by Body Weight
Stop guessing your carb-load. Here's exactly how many grams to eat per day by body weight — and why most runners get it wrong.
How Many Gels Per Hour Do You Actually Need? A Marathon Fueling Plan by Finishing Time
Generic gel advice ignores your finishing time. Here is a per-hour fueling plan for sub-3 to 5-hour marathoners — plus why slower runners need more, not less.
Boston, London, and a Warm Forecast: Adjusting Your Marathon Fueling Plan in Taper Week
Your race plan was built on cold long runs. Here is exactly how to recalibrate hydration, sodium, and gels when the forecast turns warm.
Why Do Gels Make You Feel Sick? How to Train Your Gut for Race Day
GI distress ruins more races than tired legs. Here's the science behind gel nausea and a practical gut training protocol.
Why Do I Cramp During Marathons? The Science Your Watch Can't Tell You
Cramps ruined your race? Here's what actually causes them and how to build a hydration plan that fights back.
Triathlon Nutrition: How to Fuel the Swim, Bike, and Run
A discipline-by-discipline guide to triathlon fueling — what to eat before, how to load on the bike, and why the run leg destroys most nutrition plans.
When to take your first gel during a marathon
Most runners take gels too late, wait too long between them, and end up bonking despite carrying the right number. Here's the timing strategy that actually works.
Are Garmin calorie estimates accurate — and does it matter for fueling?
Your Garmin says you burned 2,400 calories on your long run. The real number is probably different. Here's what the research says, and how to use your data more intelligently.
How to build a race-day nutrition plan from scratch
A practical framework for building your marathon or triathlon nutrition plan — what to prepare, when to test it, and what to do if things go wrong on the day.