Laktic
Today's threshold paces, adjusted for the heat.
Enter a race PR. Get LT1, Sub-T and LT2 paces slowed for the temperature and dew point at your track. Coaches: your whole roster on one board.
How it works
Three inputs. Today's paces.
Enter a race PR
1500m, 1600m, mile, 3000m, 3200m or 5000m, plus training age for mile-type PRs. The engine converts it to a 5K equivalent.
Get the conditions
One tap pulls temperature and dew point for your track from Open-Meteo, or type them in yourself.
Read the paces
LT1, Sub-T and LT2 by rep length, plus Easy, Long Run and Steady, each slowed by the day's heat score.
Features
Built for the track in August.
Heat score
Temperature plus dew point. Under 100 nothing changes; from 100 to 180 the paces slow by a rising percentage.
Zones and rep lengths
Every zone has 1–3, 4–6 and 7–10 minute rep paces. Short reps carry less of the heat penalty than long ones.
Roster and workout board
Add the team once. Pick a zone and rep length and every athlete's pace is on one board, ready to print.
Share a board link
The roster travels inside the link, nothing is stored on a server. Assistants open it on the web or in the app.
Light and dark
Follows your phone, or pick one. Dark keeps the board readable on the infield at dusk.
Sync across devices
Works without an account. Sign in only if you want the roster on your phone and laptop at the same time.
Why I built it
A coach's note
I've coached high school runners through professionals, and almost every pace calculator I tried had the same two problems. They only targeted LT2, and they overshot it: the paces came out faster than what athletes actually showed in the field by effort, RPE, and lactate testing. The more I learned about threshold training, the clearer it became that the value is in the whole band, from LT1 up to LT2, and especially in the Sub-T effort just under LT2 that Marius Bakken calls the golden zone: the best return if you run a single threshold system.
So this calculator does a few things the others don't. It builds paces for the full band, not just LT2. It corrects for mile and 1600m PRs, which high school coaches usually have and which predict threshold far too fast; a training-age buffer scales them down for an aerobic system that is still developing. It adjusts for rep length, because threshold pace for one-minute reps is not threshold pace for ten-minute reps; the accumulation of time matters. And it handles summer in the Northeast: an 80-degree day with high humidity turns a threshold session into something closer to VO2 work. The heat model reads live weather and dials the paces back so you don't have to guess.
It comes from the research, from field testing, and from feedback from athletes and coaches. The goal is simple: train smarter, adjust for distance, heat, and rep length, and always stay on the safe side.
Travis Mahoney, Laktic
Pace engine: Track and Road Performance
The zones
LT1, Sub-T, LT2, and where today's workout sits
The app turns one race PR into a 5K equivalent, then places every zone relative to it. Here is what each one means and how to use it.
Easy and Long run
Conversational. Below LT1.
Most of the week lives here. Easy runs and long runs sit under the aerobic threshold, so recovery keeps up with the volume. In heat these slow the least in percentage terms, but they still slow.
LT1
Aerobic threshold. Comfortably hard, full sentences.
The first point where lactate rises above resting levels. Steady work here builds the aerobic engine with a low cost. Long reps and steady runs are the natural fit.
Sub-T
Just under LT2. Controlled and repeatable.
Bakken's golden zone. Most of your threshold volume belongs here: fast enough to drive adaptation, slow enough to repeat two or three times a week without digging a hole. If you run one threshold system, run this one.
LT2
Lactate threshold. Roughly one-hour race effort.
The fastest pace lactate stays stable at. Valuable in small doses, easy to overshoot, and the zone most calculators aim for exclusively. Use it for shorter reps and specific race prep, not as the daily default.
Rep length and heat
Same zone, different pace.
One-minute reps at threshold are faster than ten-minute reps at threshold; the app shows 1–3, 4–6 and 7–10 minute ranges for every zone. Then today's heat score slows each one. Pick the zone, pick the rep length, and the board does the rest.
Guidance, not a lab test. Use effort and lactate readings to confirm, and use judgment on hot days.