The hard part of your week, done right.

15 min warm-up, then 30 min as hard and as even as you can. Heart rate and pace of the last 20 minutes are your threshold.

Every test is checked. Heart rate missing for over 30 s, a pause or a pace that fades at the end make it not valid, and your threshold stays the same. A start that is too fast gets a warning.

You see the new result next to the previous one and save it yourself.

Already know your threshold, for example from your Garmin? Enter heart rate and pace by hand on the watch or in the phone settings. Connect IQ apps cannot read the value your Garmin measures.

Heart rate only, your workouts then go by heart rate.

8 × 1 km, 6 × 6 min or 3 × 10 min, with 60 or 90 s rest.

Each one starts with a 15-minute warm-up and ends with a 5-minute cool-down.

A pace band and a heart-rate cap for every format, set from your threshold.

The start screen suggests today's format and rotates through all three; pick another one any time.

Outdoors with GPS or on a treadmill. Pace in min/km or min/mi, as set on your watch.

Early in a rep the app watches your pace, later your heart rate, because heart rate lags behind. Too fast? SLOW DOWN with two long vibrations.

It never nags you for running slowly. On hills, trust heart rate.

3 short vibrations = rep, 1 long = rest, soft ticks count down the end of the rest. Vibration only, no beeps.

A rep counts when its heart rate in the last minute stayed under the cap and its pace was not faster than the band. A fast rep with a good heart rate does not count, because the point is not to run faster.

A bar for every rep against your heart-rate cap, average heart rate in % of threshold, time, distance and rep pace.

Saved to Garmin Connect as a run or treadmill run, with a lap for every rep and rest and with threshold heart rate, reps in control, rep count, format and rep number as extra fields.

At most 3 sub-threshold days in 7, and not two days in a row. The method works through the rest between workouts. The guard only suggests; you can still run.

Same pace, lower heart rate? After several workouts in the same format the app notices and suggests a new test, because your threshold has likely moved.

A gentle reminder to test again 8 weeks after the last test.

History of workouts and tests. Glance: your threshold, the next SubT and this week's count.

If the app or the watch restarts during a workout, you can pick it up again.