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The TrainingZones Blog
Guides and science breakdowns on training zones, heart rate, power, and pace, to help you train smarter.
How Apple Watch Calculates Your Max Heart Rate (HRmax)
Apple never publishes the formula. What Apple does say about HRmax and zones, what the community has reverse-engineered, and how to override it.
HRmaxmax heart rateApple Watchheart rate zoneswatchOS
How Apple Watch Calculates VO2 Max (Cardio Fitness)
Apple's Cardio Fitness is the one wearable VO2 max estimate with published independent validation. It underestimates, by about 6.9 ml/kg/min on average.
VO2 maxApple Watchcardio fitnessvalidationtraining
How COROS Calculates Your Max Heart Rate (HRmax)
COROS recommends 207 − 0.7 × age for HRmax, offers three zone models, and analyses your training with lactate-threshold zones whichever one you pick.
HRmaxmax heart rateCOROSheart rate zonesEvoLab
How COROS Calculates Your VO2 Max (EvoLab)
COROS estimates VO2 max from a rolling six weeks of outdoor runs, then feeds it into Running Fitness, Marathon Level and the race predictor.
VO2 maxCOROSEvoLabrunning fitnesstraining
How Every Watch Calculates Your Max Heart Rate (10 Brands Compared)
Garmin uses Tanaka, COROS uses Gellish, Apple publishes nothing, Wahoo skips HRmax entirely. Ten brands, their formulas and zone models, in one table.
HRmaxmax heart rateheart rate zoneswearablescomparison
How Fitbit Calculates Your VO2 Max (Cardio Fitness Score)
If Fitbit shows you a range like 42-46 instead of a number, it has estimated your VO2 max from resting heart rate alone. Here is how to get a real one.
VO2 maxFitbitcardio fitness scoreresting heart ratetraining
How Garmin Calculates Your VO2 Max (and How Accurate It Is)
Garmin's Firstbeat algorithm reads pace against heart rate in short credible segments. Within 3-5 ml/kg/min of a lab with a chest strap, worse without.
VO2 maxGarminFirstbeatcardio fitnesstraining
How Matthew Brennan Trains (Five Vuelta Stages at 21)
Brennan won five stages of the 2026 Vuelta on his Grand Tour debut at 21. Under the sprint sits a track pursuiter's engine. Here is how it works.
cyclingsprintingcritical powertrack cyclingtraining
How Polar Calculates Your VO2 Max (OwnIndex and Running Index)
Polar has two systems: a five-minute resting test that needs no exercise, and Running Index from every run. One of them is much more trustworthy.
VO2 maxPolarOwnIndexRunning Indextraining
How Suunto Calculates Your VO2 Max (Fitness Level)
Suunto labels VO2 max as Fitness Level and gets it from Firstbeat, the same engine behind Garmin's, using running and walking data on specific models.
VO2 maxSuuntoFirstbeatfitness leveltraining
How WHOOP Calculates Your VO2 Max
WHOOP updates VO2 max weekly from GPS running data plus respiration rate, recovery and time in heart rate zones. A wider net than any watch casts.
VO2 maxWHOOPrecoveryrespiration ratetraining
How WHOOP Calculates Your Max Heart Rate (HRmax)
WHOOP starts with the Gellish formula, then adjusts your max heart rate from 24/7 data. It is the only major brand that says it learns the number.
HRmaxmax heart rateWHOOPstrainheart rate zones
How Faith Kipyegon Trains (the 1500m Record-Holder From Kipchoge's Camp)
Faith Kipyegon holds the 1500m and mile world records, trains in Kipchoge's Kaptagat camp under Patrick Sang, and got faster after becoming a mother.
runningmiddle distancemileVDOTtraining
How Johannes Klæbo Trains (Cross-Country Skiing's Bottomless Engine)
Klæbo won all six events at the 2026 Winter Olympics in the most aerobic sport there is. The Norwegian model behind it, and your own I1 to I5 zones.
cross-country skiingaerobic baseintensity zonesendurancetraining
How Kilian Jornet Trains (and Why He Counts Metres, Not Kilometres)
Kilian Jornet measures training in vertical gain, builds a 3 to 4 month easy base every year, and coaches himself by feel. The method and the 2026 season.
trail runningverticalaerobic baseski mountaineeringtraining
How Garmin Calculates Your Max Heart Rate (HRmax)
Garmin estimates HRmax from your age (208 − 0.7 × age), then raises it from new peaks. How auto-detection works, what it drives, and how to set it.
HRmaxmax heart rateGarminheart rate zonesVO2max
How Strava Calculates Your Heart Rate Zones
Strava uses 220 − age, falls back to 190 bpm with no age on file, and silently rewrites your zones on your birthday. Here is how to take control.
heart rate zonesStravamax heart rateHRmaxtraining zones
How Wout van Aert Trains (the VLamax Fix Behind His Roubaix Win)
Van Aert won the fastest Paris-Roubaix ever, then two Vuelta stages. The training idea behind it is one number his team spent years lowering: VLamax.
cyclingVLamaxfat oxidationcyclocrossfuelingtraining
How Wahoo Calculates Your Heart Rate Zones (THR, not HRmax)
Wahoo is the one brand that builds zones from threshold heart rate rather than maximum. It seeds THR at 88% of a Tanaka estimate. Here is how to fix it.
threshold heart rateLTHRWahooheart rate zonesSYSTM
How Samsung Galaxy Watch Calculates Your Max Heart Rate
Samsung starts at 220 − age, now layers Galaxy AI personal zones on top, and keeps the setting per exercise type rather than once for everything.
HRmaxmax heart rateSamsungGalaxy Watchheart rate zones
How Enric Mas Trains (Leading the Vuelta a Year After Surgery)
Mas lost half of 2025 to a blood clot and was 32nd at the Giro in May. In September he leads the Vuelta. How the comeback was built, block by block.
cyclingFTPpower to weightGrand Tourtraining
How Nadia Battocletti Trains (Olympic Silver off 90km a Week)
Battocletti has Olympic and world 10,000m silver on 80 to 90km a week, coached by her father. The low-volume, cross-country-built system behind it.
runningcross countryaerobic baseVDOTtraining
How Kasia Niewiadoma Trains (and How She Won on Mont Ventoux)
Kasia Niewiadoma soloed Mont Ventoux to take yellow at the 2026 Tour de France Femmes. The recon, the pacing and the watts per kilogram behind it.
cyclingclimbingFTPwatts per kgtraining
How a Fast Age-Grouper Trains on 8 Hours a Week (With a Full-Time Job)
How a fast amateur trains around a job and a family on eight hours a week: two hard sessions, everything else easy, and why the time limit helps.
trainingpolarizedage groupnutritiontime crunched
How Josh Kerr Trains (and How He Finally Broke the Mile World Record)
Josh Kerr ran 3:42.66 on 18 July 2026 and ended a 27-year-old mile world record. The training and pacing behind Project 222.
runningmiddle distancemileVDOTtraining
How Katie Ledecky Trains (the Most Aerobic Athlete in the Pool)
Katie Ledecky races a pace, not an opponent, on huge aerobic volume held to precise splits. How she trains, and why swimmers set zones by stopwatch.
swimmingcssdistanceaerobic basepace
How Lucy Charles-Barclay Trains for the Heat (and the Hydration Mistake That Cost Her Kona)
The 2023 Ironman World Champion prepares for Kona with a six-week heat block, then lost a Kona lead to a sodium overdose. What long-course athletes get wrong about sweat and salt.
triathlonironmanheathydrationsweat rate
How Mark Allen Trained (and Why He Ran Slower to Get Faster)
Six-time Ironman World Champion Mark Allen capped his heart rate with Maffetone's 180-formula and watched his pace at that heart rate transform. A formula you can run now.
triathlonmaffetoneheart rateaerobic baseMAF
How Michael Phelps Fueled 80,000 Meters a Week (and the 12,000-Calorie Myth)
Michael Phelps never ate 12,000 calories a day. The real number, the 80,000-meter weeks behind it, and what it says about your own calorie needs.
swimmingnutritioncaloriesTDEEfueling
How Sifan Hassan Trains (One Engine, From 1500m to the Marathon)
Sifan Hassan medals from 1500m to the marathon. The range behind it, and how one race result predicts your time at every other distance.
runningmarathonmiddle distancerace predictiontraining
How Alex Yee Trains (the Runner Who Wins Triathlons)
Alex Yee won Olympic gold with the fastest run off the bike in the field. How he built a triathlon around that weapon, and how to pace a run on tired legs.
triathlonrunningrunning powerthresholdtraining
How Cole Hocker Trains (One Engine, From the Mile to the 5000)
Cole Hocker is Olympic 1500m champion, world 5000m champion and the second-fastest indoor miler ever. How one number predicts your pace at every distance.
runningmiddle distanceVDOTtracktraining
How Courtney Dauwalter Trains (No Coach, No Plan, No Heart-Rate Monitor)
The best ultrarunner alive trains by feel: no coach, no plan, no heart-rate data. Why it works for her, and what a heart-rate cap gives the rest of us.
ultrarunningtrail runningaerobic basetraining by feeltraining
How Léon Marchand Trains (Phelps's Coach, and a Stopwatch Instead of a Heart Monitor)
Marchand trains under Bob Bowman, the coach who made Michael Phelps, on pace and short rest rather than heart rate. Why swimmers set zones from a stopwatch.
swimmingcssthresholdpacetraining
How Mathieu van der Poel Trains (One Engine, Three Sports)
Van der Poel is world champion on the road, in cyclocross and on gravel. How one engine spans three disciplines, and why he isn't sure cyclocross helps his road form.
cyclingcyclocrossFTPpowertraining
How Primož Roglič Trains (the Ski Jumper Who Started Cycling at 22)
Roglič was a pro ski jumper who started cycling at 22, then won four Grand Tours. What the late switch teaches about starting a sport as an adult.
cyclingcritical powerlate starteraerobic basetraining
How Remco Evenepoel Trains (the Ex-Footballer With a Legendary Engine)
Evenepoel came to cycling from football and won Olympic time-trial gold. His power-based method, why his famous VO2max is disputed, how to estimate yours.
cyclingtime trialVO2maxpowertraining
How Demi Vollering Trains (and How She Won a Second Tour de France Femmes)
Vollering cut her racing from 29 days to 18, bet on training blocks over race days, and won the 2026 Tour de France Femmes. The method, and what to steal.
cyclingthresholdcritical powerfuellingtraining
How Elite Rowers Train (20 Hours a Week for a 6-Minute Race)
A 2k rowing race lasts six minutes, yet elite crews train 15 to 30 hours a week and spend around 80% of it easy. Why that works, and what to do on the erg.
rowingaerobic baseconcept2intensity distributiontraining
How Kristian Blummenfelt Trains (and What He Eats While Doing It)
Kristian Blummenfelt runs the Norwegian method in three sports: lactate-guided thresholds, obsessive measurement, and a carb intake that rewrote the rules.
triathlonNorwegian methodlactatefuellingtraining
How Marianne Vos Trains (and What Overtraining Cost Her)
Vos has won at the top of cycling for two decades. The most useful part of her career is the year she lost to overtraining, and what she changed afterwards.
cyclingovertrainingrecoveryaerobic basetraining
How Eliud Kipchoge Trains (and Why He's Still Out There at 41)
Kipchoge never runs a session flat out. The 80/50 week behind the greatest marathon career ever, and why it has him racing seven continents at 41.
marathoneasy runningaerobic baserunningtraining
How Jakob Ingebrigtsen Trains (and What the Achilles Injury Exposed)
Ingebrigtsen's week: two double-threshold days, every rep capped by a lactate meter. The injury blind spot it missed, and the post-surgery comeback.
Norwegian methoddouble thresholdlactateIngebrigtsenrunningtraining
How Jonas Vingegaard Trains (and Why He Rode the Giro First in 2026)
Vingegaard's training rests on measured thresholds, few race days and years of patience. The method, the 2026 Giro-Tour change, and what to copy.
thresholdftptraining loadcyclingtraining
How Tadej Pogačar Trains (and Why He Got Heavier in 2026)
Pogačar's training: a mountain of easy Zone 2, a small dose of very hard work, gym strength, and a deliberate 2026 weight gain for the Classics.
zone 2polarized trainingpower to weightcyclingtraining
Rowing UT2: What It Is and Why It Builds Your Engine
UT2 is rowing's easy aerobic base band. What it means, the heart rate and stroke rate to hold, how it fits the UT2–AN system, and how to row it well.
rowingUT2aerobic baseheart rate zonesconcept2
Beyond the Numbers: Special Training Intensities, Part 1 (Fatmax to Sweet Spot)
Fatmax, MAF, Zone 2, Tempo and Sweet Spot are named training intensities between the numbered zones. What each one is, where it sits, and when to use it.
training zonesfatmaxsweet spotzone 2tempo
Beyond the Numbers: Special Training Intensities, Part 2 (Threshold to Sprint)
Threshold, sub-threshold, Critical Power, VO2max and the anaerobic top end: the named training intensities at the hard end and what each one trains.
training zonesthresholdVO2maxcritical powernorwegian method
Heart Rate Reserve: Better Zones with the Karvonen Method
What heart rate reserve (HRR) is, the Karvonen formula that turns it into training zones, why it beats plain %HRmax, and how to measure the two inputs.
heart rate reserveKarvonenheart rateresting heart ratetraining zones
How to Actually Train Zone 2 (and Not Waste It)
A practical guide to Zone 2 training: session length, weekly volume, how to stay in the zone, the gray-zone trap, and how to tell it's working.
zone 2zone 2 trainingaerobic basepolarized trainingendurance
Why Your LTHR Zone 2 Is Higher Than Your %HRmax Zone 2
Switched your watch to LTHR zones and Zone 2 jumped 20–30 beats? Nothing is broken. Why %HRmax and LTHR zones differ and why Zone 2 means three things.
heart rate zonesLTHRzone 2HRmaxGarmin
LT1, LT2, and LTHR: The Lactate Thresholds Explained
What LT1, LT2 and LTHR mean, where they sit on the lactate curve, and how aerobic threshold, anaerobic threshold, OBLA, MLSS and VT1/VT2 map onto them.
lactate thresholdLT1LT2LTHRtraining zones
The Best Free Power Zone Calculator (and How to Use It)
Enter your FTP and get all seven cycling power zones in watts, free, no email or account. How the calculator works and how to estimate FTP inside it.
power zone calculatorFTPpower zonescyclingtraining zones
The Coggan Power Zones: All 7 Levels Explained (% of FTP)
Andrew Coggan's 7 power zones, each as a percentage of FTP: the watts range, what it trains, how it feels, and how to set yours from an FTP test.
coggan power zonesFTPpowercyclingtraining zones
What a Training Zone Calculator Actually Does (and How to Use Yours)
A training zone calculator turns your max heart rate, threshold, FTP or race time into personal easy, tempo and hard ranges. Which input to use and how to act on it.
training zonesheart ratepowerpacezone calculator
Managing Training Load: TSS, CTL, ATL and the Numbers That Actually Matter
How to monitor endurance training load: normalised power, TSS, ATL/CTL/TSB, the acute:chronic workload ratio, and why load is feedback, not a target.
training loadTSSCTLACWRmonitoringovertraining
The Norwegian Method: Double Threshold Training, Explained
What the Norwegian method is, the science behind lactate-guided double-threshold training, where it falls short, and who uses it, from Ingebrigtsen on.
Norwegian methoddouble thresholdlactateIngebrigtsentraining philosophiesthreshold
VDOT Explained: How Jack Daniels Turns One Race Into Every Training Pace
What VDOT is, how Jack Daniels' Running Formula turns one race into easy, marathon, threshold, interval and repetition paces, and where it misleads.
VDOTJack Danielsrunningpacetraining zonesVO2max
What Heart Rate Zone Should You Train In?
Which heart-rate zone to train in and when: most time easy in Zone 2, a controlled dose at threshold, a little in Zone 5. Plus how to find your zones.
heart ratetraining zoneszone 2polarized trainingLTHR
Zone 2 Heart Rate, Explained
What Zone 2 training is, why it builds your aerobic base, how to find your own Zone 2 heart rate with the talk test, LT1 or MAF, and how much of it to do.
zone 2heart rateaerobic baseMAFtraining zones
The 30/15 Interval: The Cult Session That Actually Delivers
Rønnestad's 30/15 intervals: 3 sets of 13 x 30 seconds on, 15 off. What the studies found, how to run one, and why the last set hits max heart rate.
intervalsVO2 maxcyclingRønnestad
What's a Good FTP (and Watts per Kilogram)?
What counts as a good FTP and a good watts-per-kilogram, with ranges from beginner to pro, why W/kg beats raw watts on climbs, and how to test yours.
FTPwatts per kgpowercyclingpower-to-weight
Friel's Heart-Rate Zones: 5, 7, and Why Every Platform Numbers Them Differently
Joe Friel's LTHR zones explained: the 5-zone model, the 5a/5b/5c split that makes it 7, how intervals.icu renumbers them, and how to test your LTHR.
heart rateLTHRFrieltraining zonesintervals.icu
How to Find Your Lactate Threshold
What lactate threshold is (LT1 vs LT2), why it anchors your zones, and how to find it: a 30-minute LTHR field test, race or power methods, or a lab test.
lactate thresholdLTHRthresholdtestingtraining zones
Finding Your Maximum Heart Rate
What max heart rate is, why the 220 minus age rule is shaky, and how to estimate or field-test yours. Includes a six-formula calculator.
heart ratemax heart ratetraining zones
How to Set Your Training Zones (and Actually Use Them)
How to find your heart-rate, power and pace zones: pick the right anchor, test it with a field test, then train by it with a polarized week.
training zonesheart rateFTPpace
How Rémi Bonnet Trains (2,194 Metres of Climbing an Hour)
Bonnet climbed 1,000m in 27:21 on a 50% gradient. Vertical ascent rate is the honest number in uphill sport, and here is how to work out your own.
ski mountaineeringskimoverticaluphilltraining
How Fitbit Calculates Your Max Heart Rate (HRmax)
Fitbit estimates HRmax with 220 − age, then personalises your zones using heart rate reserve. That second step is why its zones look wrong to runners.
HRmaxmax heart rateFitbitheart rate zonesheart rate reserve
How Harald Østberg Amundsen Trains (a Crystal Globe, No Olympic Medal)
Amundsen won the overall World Cup, then finished 4th, 6th and DNF at the 2026 Olympics. Season-long form and one-day form are different training problems.
cross-country skiingpeakingconsistencytraining loadtraining
How Quentin Fillon Maillet Trains (Eight Olympic Medals, Every Format)
France's most decorated Olympian has medalled in every biathlon format, from a 23-minute sprint to a 50-minute individual. That range is a threshold story.
biathlonthresholdLTHRpacingtraining
How Suunto Calculates Your Max Heart Rate (HRmax)
Suunto defaults to 220 − age and then draws unusually narrow zones on top of it, which is why the same run lands in a different zone than on a Polar.
HRmaxmax heart rateSuuntoheart rate zonesintensity zones
How Gesa Krause Trains (a Third European Title, Eight Years Later)
Krause won European steeplechase gold at 34, eight years after her last one and three years after her daughter was born. The zone lesson inside.
steeplechasemax heart ratelongevityrunningtraining
How Sturla Holm Lægreid Trains (Shooting Straight at 170 bpm)
Five medals in five races at the 2026 Olympics, none of them gold. Biathlon is decided by how fast your heart rate falls, and that is a trainable number.
biathlonheart rateheart rate recoverycross-country skiingtraining
How Polar Calculates Your Max Heart Rate (HRmax)
Polar still defaults to 220 − age and draws five zones as clean 10-point bands of it. What that costs you, and how to replace it per sport.
HRmaxmax heart ratePolarheart rate zonesPolar Flow
How Jessie Diggins Trains (Twice a Day, and Why She Calls Food Fuel)
America's most decorated cross-country skier trains twice a day, six days a week. The reason she talks about fuelling is the reason the volume is possible.
cross-country skiingfuellingenergy availabilitytraining volumetraining
How Therese Johaug Trains (What a Comeback at 36 Actually Returns)
Johaug unretired at 36, took three silvers and a bronze at the 2025 Worlds, then stopped for good. What came back, and what did not, is the useful part.
cross-country skiingaerobic baselongevitycomebacktraining