Core feature
Lactate curve, eight thresholds, in one click
Paste your step-test values — we draw the curve and surface LT1, LT2, OBLA (2.0–3.5), IAT, D-max, log-log in parallel. No spreadsheets, no formulas.
Try calculating lactate thresholds for free — no sign-up neededTry demo
For coaches & athletesLactate testing app
Lactate testing app
and training platform
Run the test, get LT1 and LT2 by six methods, and turn them straight into zones. Then use them: rides, runs and swims arrive on their own from Strava, Garmin or Apple Health, you read load and form, laps and peaks, and next week goes back out to the watch — all of it anchored to numbers you measured, not a percentage of a guess.
LT1 / LT2Zones & PDF reportCalendar & plannerLoad & form
LT2 Threshold
340 W
Zone 2 Power
187–255 W
Form (TSB)
+12 · Fresh
Cycling · Running · Triathlon · SwimmingLT1, LT2, OBLA, IAT, D-max, Log-logGarmin · Strava · FIT · Apple HealthForm & Fitness · TSS · Zone distributionRace planning · Live workouts · iOS appCoach & athlete workspace
Explore what LaChart can do
Tap a category to jump straight to features — testing, planning, integrations, coaching and more.
For whom
Lactate testing for cyclists, runners & triathletes
From the first home lactate test to a full coaching workspace — LaChart fits the way you train.
Three workspaces · one app
Athlete, coach & tester workspace
LaChart adapts to how you use it — train yourself, manage athlete lactate tests, or run tests for clients. Same data, three completely different shells.
For athlete
Train yourself. Tap your numbers.
A calm dashboard built around today. Form and fitness at a glance, threshold trend over months, every interval ready for a lactate sample. Mobile-first.
- Form ring · TSB — fresh, optimal, productive, overreaching, in plain English.
- Today's training — above the fold — open, do, log lactate, done.
- Tap any interval — to log a blood sample — your curve learns.
- Threshold trend — over weeks — LT1 and LT2 moving right.
- Native iOS app — bottom tabs, swipe between sports, Apple Health sync.
Fresh
Fitness
59
Fatigue
31
LT1
374W
2.7 mmol · 146 bpm
LT2
418W
4.2 mmol · 160 bpm
Daily TSS · this week27.4 — 3.5
M97
T109
W101
T103
F93
S14
S·
418W
+ 12 W over 8 tests
Time
16h 42m
TSS
517
Distance
369 km
Sessions
13
Home
Test
Cal
Train
What's inside
Six things you can do today in LaChart
The features paying users use most, with real screenshots from the app — not stock illustrations.
● Garmin● Strava● FIT files● Apple Health
Auto-syncEvery workout flows in automatically
Connect once. Rides, runs and swims arrive with power, HR, pace and laps — pre-categorised by intensity.
Platform features
From first sample to race day
28 features, grouped by what you're actually trying to do. Open the part that matters to you, or read every feature in detail →
How it works
Anatomy of a lactate test in LaChart
From raw step-test values to a branded PDF, structured workouts and a tracked curve — five steps, one platform.
Enter test values
Stage power / pace + blood lactate + HR. Step or ramp protocol — any test design.
Eight thresholds calculated
LT1, LT2, OBLA (2.0–3.5), IAT, D-max, log-log, LTP1, LTP2 — in parallel, instantly.
Zones auto-generated
5 training zones with power / pace / HR ranges, tailored to cycling, running or swimming.
Plan structured workouts
Drag intervals at your new zones onto any day of the calendar. Run them live from the app.
Branded PDF + curve history
Export a polished PDF (your logo on Coach plan). Each new test overlays on the curve so progress is visible.
Core feature
Lactate Curve Generation
Enter your test values — power, heart rate, lactate, pace — and instantly generate the lactate curve. Calculate all critical thresholds in one interactive graph.
- Step or ramp protocol — any test design
- LT1, LT2, OBLA, IAT, D-max, log-log calculated in parallel
- Baseline adjusts for individual resting lactate
LT1 & LT2OBLA 2.0–3.5IATD-maxLog-log
Zones
Train inside your zones, not someone else's
Your zones are derived from your last lactate test — power, pace and heart rate side by side. Update the test, zones update everywhere.
- 5-zone or Seiler 3-zone models
- Power, pace and HR per sport
- Auto-updates when a new test is recorded
Progress tracking
Historical test comparison
Overlay multiple lactate tests to visualize your progression. Watch your LT1 and LT2 move to higher intensities as your fitness improves.
- Compare multiple test curves on one chart
- Track zone shifts over training seasons
- Visualize threshold improvements
- Export comparison PDF reports
Form & fitness
Read your fitness, fatigue and form at a glance
CTL, ATL and TSB tracked every day. A plain-English status word — fresh, optimal, productive, overreaching — so you always know what today's training should be.
- Auto-updated from every Strava or FIT activity
- 14-day, 6-week and 3-month views
- Plan race peaks around predicted form
Training log
Every interval, with a lactate dot
Open any training and tag any interval with a blood sample. Empty dots are tap-to-log. Every sample feeds back into your curve and your zones.
- Power, HR, cadence and pace per interval
- Auto-detected laps from FIT and Strava
- "Ready for lactate" filter surfaces untagged sessions
Calendar
Your whole training week, month, season
An interactive calendar of every workout — completed, planned, with lactate, without. Click any day to see the session, intervals and zones.
- Color-coded by sport and intensity
- Strava and FIT activities appear automatically
- Daily TSS bars track weekly load
PDF reports
Professional test reports in seconds
Branded PDF with your lactate curve, HR overlay, color-coded zones, threshold table, previous-test comparison and training recommendations.
- Curve + HR overlay on a single page
- All thresholds (LTP1, LTP2, OBLA, IAT)
- Stage-by-stage results table
- Personalised training recommendations
The science
LT1, LT2, OBLA & D-max — four lactate threshold methods
LaChart calculates lactate thresholds using OBLA, D-max, IAT and Log-log — the four most-cited methods in exercise science. Use them side by side or stick to your federation's standard.
OBLA
Onset of Blood Lactate Accumulation
Fixed at 4.0 mmol/L. The power output at which your blood lactate first reaches 4 mmol/L on a graded test.
LT₂ = pace @ 4.0 mmol/L
Dmax
Geometric inflection
The point where your curve bends most sharply from the line connecting baseline lactate to peak. Independent of fixed values.
LT₂ = max perpendicular distance
IAT
Individual Anaerobic Threshold
Takes your individual baseline lactate and adds 1.5 mmol/L. More accurate for highly trained athletes with low resting values.
LT₂ = baseline + 1.5 mmol/L
Log-log
First-rise inflection
Plots log(lactate) vs log(intensity). The first clear break in slope marks LT1 — the aerobic threshold.
LT₁ = first slope change
Learn
Blood lactate testing — the science explained
Long-form guides on blood lactate testing protocols, threshold detection methods (LT1, LT2, OBLA, D-max), and what your lactate curve actually means for training zones.
Protocol · 14 min
How to do a lactate test at home
Equipment, step protocol, blood-sampling technique, and the four mistakes that ruin a test.
Read article →Reading · 11 minRead your lactate curve step-by-step
Spot LT1, LT2, the curve shape clues, and the red flags that mean re-test.
Read article →Zones · 9 minLT1 vs LT2 — what they mean for training
The physiological difference, why both matter, and how to build zones from each.
Read article →Concepts · 10 minFTP vs LT2 — are they the same?
Usually yes, sometimes no. When they diverge and which one to actually train against.
Read article →Methods · 11 minOBLA, D-max, IAT, log-log compared
Why no single threshold method is perfect — and why LaChart uses an ensemble of all of them.
Read article →Algorithm · 12 minHow LaChart calculates LT1 / LT2
Inside the 8-method ensemble, isotonic regression, and the noise-detection guards.
Read article →Integrations
Strava & Garmin integration for lactate tracking
Connect Strava, upload Garmin/Wahoo FIT files, or enter data manually. Every workout and lactate value flows into one platform.
Strava
Auto-sync activities, full interval detection, power graphs and HR zones.
FIT files
Garmin, Wahoo, Polar, Suunto — every device supported.
Manual entry
Log any workout in 30 seconds — even ones without a head unit.
Used by
Lactate testing used by cyclists, runners & triathletes
★★★★★
"The first lactate app that doesn't feel like Excel. I do my own home tests every 4 weeks and the curve drops into my training within seconds."
★★★★★
"I coach 14 triathletes. The athlete switcher and the "ready for lactate" filter saved me two hours a week. Status dots are pure gold."
★★★★★
"I switched from spreadsheets after my first test. Seeing LT1 and LT2 land on the same chart — with the previous test underneath — is a game changer for steady-state work."
Just launchedGet the app
LaChart for iPhone is here
Free on the App Store. Today's training, Form / Fitness / Fatigue home-screen widget, Apple Health sync, push notifications, and on-device lactate recording. Android is next.
Download on theApp StoreComing toGoogle Play
Requires iOS 16 or later · Free · Premium features unlock with your existing account.
Inside the iPhone app
Real screens, not mockups
Every shot below is from the build that's live on the App Store right now — dashboard, lactate testing, planning, calendar and analytics.
Calendar
Planned & completed sessions in one view.
Analytics
Week-by-week load, volume by sport, trends.
Dashboard
Form, Fitness, Fatigue + week TSS at a glance.
Lactate test
LT1 / LT2 with last test details and full training zones.
Live recording
Capture stages, lactate + HR right on the bike.
Per-interval data
Power, HR and lactate side-by-side per lap.
Lap power chart
Smart lap detection works on Strava + FIT.
Plan workouts
Zone-aware builder with TSS preview.
Free · No sign-up
Have 30 seconds? Try it on your own data
Drop your step-test values into the free Lactate Calculator. You'll see your curve, LT1, LT2, OBLA, IAT, D-max and matching training zones in real time — no account required.
- Eight threshold methods calculated in parallel
- Power, pace and heart-rate zones tailored to your sport
- PDF export included — save and share immediately
Already on LaChart? Sign in →
No sign-up
Pricing
Start free. Go Pro when you're ready.
Your first three lactate tests, your curve and your zones are free — long enough to watch a threshold move. Athlete adds unlimited tests, the full history behind them, and a calendar that pushes structured workouts to your Garmin. Coach does all of it for a whole roster. Both start with 2 weeks free. Cancel anytime.
🎁 Coaches: 2 weeks free — no charge today
Run your full roster of athletes on the Coach plan free for 2 weeks. Cancel anytime before it ends and you pay nothing.
Free
€0/ month
- ✓ 3 lactate tests
- ✓ Garmin & Strava sync
- ✓ Add lactate values to intervals
- ✓ Connect with your coach
- ✓ Basic analytics
Athlete
€6.99/ month
🎁 Start with 2 weeks free
Test as often as you train, and keep every curve to compare against.
Plan the week and push structured workouts straight to your Garmin.
Lactate testing
- ✓ Unlimited lactate tests
- ✓ Full test history — compare every curve
- ✓ Population comparison
- ✓ PDF export of test reports
Training platform
- ✓ Push structured workouts to your Garmin
- ✓ Plan your week in the calendar
- ✓ Sessions prescribed from your lactate test
- ✓ Start trainings from the app & smart trainer
- ✓ Load, form and fitness over the full history
- ✓ Priority support
Coach
€14.99/ month
🎁 Start with 2 weeks free
Test your whole roster and send each athlete a report with your name on it.
Plan their weeks and push every session to their watch.
Lactate testing
- ✓ Unlimited athletes
- ✓ Unlimited PDF report generation
- ✓ PDF branding — your logo, title & address
Training platform
- ✓ Push each athlete’s session to their Garmin
- ✓ Plan workouts for your athletes
- ✓ Coach dashboard & overview
- ✓ Everything in Athlete
FAQ
Lactate testing — common questions
Everything you need to know about blood lactate testing, LT1/LT2 thresholds, and LaChart. Can't find it? Email us.
What is lactate threshold and why does it matter?+
Lactate threshold is the intensity at which lactate accumulates in your blood faster than it's cleared. It's the single most useful number for endurance training because it sets your tempo / threshold / steady-state ceiling — and it shifts as you train. LaChart finds it from a graded test in 60 seconds.
How accurate is the calculator vs a lab?+
LaChart uses the same OBLA / Dmax / IAT / Log-log methods sport-science labs use. Accuracy depends on your sampling protocol — same protocol in and you get lab-comparable thresholds.
Do I need to register to use the calculator?+
No. The free calculator runs without an account. A free account adds saving, history, comparison and PDF export.
Which sports does LaChart cover?+
Cycling, running, swimming and triathlon. Power-based for bike, pace-based for run / swim, HR overlay on every chart.
Can I generate a PDF report from my lactate test?+
Yes. After a test you can download a branded PDF with the lactate curve, HR overlay, all thresholds (LTP1, LTP2, OBLA, IAT), the five training zones, stage-by-stage results, a comparison with your previous test and personalised training recommendations.
Is my data exportable?+
Yes. Every account can export training history (CSV) and individual tests (PDF). We don't lock your data in.
Run your first blood lactate test — it's free
No credit card. No downloads. Enter your lactate test values and see your LT1 & LT2 thresholds in seconds.
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