Constantin: monitor effort drift against your session average

[Łukasz Szmigiel]

Constantin

Constantin helps you compare how you are moving right now against your workout average. It shows three focused workout views: drift, pace, and heart rate.

Compatible with UI2 Suunto devices, including Suunto 9 Peak Pro and newer.

Press the watch’s upper button to move to the next view. Hold the upper button to move back to the previous view.

Drift View

The drift screen shows both metrics side by side on a single combined chart.

The left panel plots two series:

• pace deviation from your session average (top)
• heart rate deviation from your session average (bottom)

Each series stays centred on its own baseline. Moving above the baseline means ahead of average for pace, or above average for heart rate.

The right panel shows a status word and the current delta value for each metric. Pace shows AHEAD (faster), STABLE, or FADE (slower). Heart rate shows HIGH, STABLE, or LOW. Values are coloured green or red when outside the stable range, and white when stable.

Pace View

The pace screen shows:

• current pace (mid)
• average pace (bottom)
• the difference between current and average pace (top)

A green difference means you are faster than your average pace.
A red difference means you are slower.
Small differences within 10 seconds per kilometre stay white.

The graph shows the recent trend of your pace difference over roughly the last 60 seconds. It is designed to show whether you are moving closer to or further away from your workout average, without overreacting to brief stops or missing pace samples.

Heart Rate View

This view shows:

• current heart rate (mid)
• average heart rate (bottom)
• the difference between current and average heart rate (top)

Heart rate values are shown in beats per minute.

A green difference means your current heart rate is below your average.
A red difference means it is above average.
Small differences within 5 bpm stay white.

The graph shows the recent trend of your heart-rate difference over roughly the last 60 seconds, so you can see whether your effort is drifting above or below your workout average.

Graph Behavior

The graph scale adjusts dynamically.

On the pace and heart-rate views, the dot marks the latest chart point. The line shows recent changes in the difference between your current value and your workout average.

On the drift view, the dotted AVG lines represent the reference baseline for each metric. The pace and heart-rate lines show recent deviation from those baselines in one combined view.

Numbers update every second. The graph adds a new point every 10 seconds, based on the recent valid data collected during that period.

At the beginning of a workout, graphs may take a short moment to appear while the watch collects enough valid pace and heart-rate data.

Workout Summary

After the workout, Constantin can add these values to the exercise summary:

• Pace AVG: your average pace for the workout
• HR AVG: your average heart rate for the workout
• Pace VAR: the average percentage variation between your current pace and average pace during the workout
• HR VAR: the average percentage variation between your current heart rate and average heart rate during the workout

The VAR values are unsigned percentages. A lower VAR means your pace or heart rate stayed closer to the workout average. A higher VAR means it fluctuated more.

How To Use

Start your workout as usual, add Constantin as a SuuntoPlus app, and use it during the activity to quickly check whether your current effort is above or below your session average.

Values may show -- until the watch has enough valid speed or heart rate data.

Contact

For questions or feedback, contact: constantin@szmigiel.design

Changelog

1.39 (2026-05-06)

• Improved stability when using Constantin during a workout, especially when switching screens or running it alongside other SuuntoPlus apps.
• Pace and heart-rate charts now focus on the most recent minute, making short-term changes easier to read at a glance.
• Charts handle stops and missing pace samples more gracefully, avoiding misleading spikes during run-stop-run sessions.
• Refined chart appearance with clearer trend lines and less visual clutter.

1.25 (2026-05-04)

• Fixed a crash when opening the Constantin screen during an active workout.
• Reduced UI memory pressure when running alongside other SuuntoPlus apps; replaced multiple chart canvases with a single shared canvas.