Lactate readings without context are just numbers
You prick your finger, see "3.8 mmol/L" on your meter. You jot it down somewhere— notes app, spreadsheet, back of your hand. A week later, you can't remember what workout it was from, what power you were holding, or how you felt.
LacTrace turns each measurement into a trace
A trace is your lactate reading linked to the exact moment in your workout— power, pace, heart rate, RPE, all connected. Over time, your traces build a picture of your unique physiology. Not from formulas. From your actual data.
Make every measurement count
From mid-workout entry to post-session analysis, LacTrace captures the full context of every lactate reading. See the full user guide →
Link Traces to Workouts
Tap the exact moment on your workout timeline. LacTrace captures power, HR, pace—everything happening when you took that reading.
Auto-Link During Workouts
Enter lactate mid-workout. When your activity syncs from intervals.icu, LacTrace automatically links your traces to the right moments.
Track Progress Over Time
Compare lactate curves across training periods. See your fitness improvements visualized as your curve shifts right—more power at the same lactate.
Coach & Athlete Sharing
Share your data with coaches or training partners. Coaches can view, add, and edit traces. Training partners get read-only access.
Formal Step Tests
Upload FIT files from structured step tests. LacTrace parses stages, fits curves, and calculates LT1/LT2 thresholds automatically.
Multi-Sport Support
Separate profiles for cycling, running, and swimming. Each sport maintains independent lactate curves and training zones.
Built for serious athletes
Clean, focused interfaces that put your data front and center. Every screen designed for quick insights.
Dashboard
Your lactate curve at a glance with recent traces
Trace History
Every measurement logged with full workout context
Activity Calendar
Synced workouts from intervals.icu with trace markers
Powered by
intervals.icu
Connect your intervals.icu account and let LacTrace handle the rest. Activities sync automatically—no manual uploads, no delays.
- Real-time webhook sync
- Automatic activity linking
- FIT file parsing for precision
- Zero-configuration setup
Requires a free intervals.icu account
Complete Workout
Finish your training session on any device
Instant Webhook
intervals.icu triggers sync within seconds
Traces Auto-Link
Your lactate readings connect to exact workout moments
See your curve shift over time
Compare lactate curves from different training periods. Watch your fitness improve as your curve moves right—more power or pace at the same lactate level.
Multi-Layer Comparison
Overlay up to 5 training periods. Each layer shows traces from a date range with its own fitted curve.
Step Test Integration
Add formal step tests as reference curves. Compare field traces against lab-quality protocols.
Intensity Distribution
See where you spend your training time relative to your lactate thresholds. Zone distribution at a glance.
30 days free. Then choose.
Full access during your trial. Cancel anytime before it ends.
$8/month
$72/year