Indie App Spotlight: Ready to Run shows Garmin runners when heat makes a run risky

Before a run, the useful questions are simple: is the body ready, is the weather safe, and is training on track? A Garmin answers them across half a dozen widgets and the Connect app. Ready to Run, a Connect IQ watch face by Trudelta, puts all three on one screen with a traffic-light colour scheme, so a glance before heading out shows what needs attention that day.

It also shows WBGT, the heat stress measure that sports bodies use to decide when to add drink breaks or cancel events, which no stock Garmin face offers.

How Ready to Run works

TL;DR: Ready to Run splits the face into three groups: body readiness at the top right, goals and performance at the top left, and weather across the lower half. In the Pro version, every reading is coloured red, amber or green, and the hour and minute digits take the average colour of the body and weather groups, so the time itself says whether today is a go.

Body readiness

The top right shows Body Battery, recovery time and the acute-to-chronic workload ratio, which compares the last seven days of running with the previous four weeks.

Goals and performance

The top left shows VO2 max, active MET-hours over seven days and the running day streak. Seven-day distance or seven-day intensity minutes can be shown instead.

Runners who live at moderate or high altitude can show an elevation-compensated VO2 max. Garmin’s altitude acclimation feature does not offer this, and Trudelta argues that it should.

Weather and heat

The lower half shows apparent temperature, the chance of rain, the barometric pressure trend, air quality, UV index and WBGT.

Why WBGT matters for runners

Wet bulb globe temperature combines air temperature, humidity, wind speed and the heat of direct sun into one figure for heat stress on the body. Air temperature alone misses most of that: a still, sunny, humid morning can be far more dangerous than a hotter, dry and breezy one. With extreme heat becoming more common, a reading built for exercise is more useful than the temperature on a weather app.

Ken, who built the face, uses his own rules with it:

• Above about 26°C (80°F) WBGT, he carries a hydration pack or shortens the run.
• Above about 31°C (88°F) WBGT, he takes a rest day or runs on the treadmill.
• With a UV index above 5, he puts on sun protection before going out.

Heat tolerance depends on acclimation, so a runner used to hot, humid weather will feel less strain at the same WBGT than one who is not.

How the colours are set

• VO2 max follows Garmin’s own colour ranges.
• Goals such as seven-day MET-hours, distance and the running streak are green when reached, amber at 70 to 99 per cent, and red below that. Every goal can be changed.
• The colour of the hour digits is the average of the body readiness readings, and the colour of the minute digits is the average of the weather readings.

Compatibility

Ready to Run works on almost every Garmin watch that supports Connect IQ apps, apart from the oldest models, roughly ten years old or more. That covers current Forerunner models and the rest of Garmin’s running range. The colour coding needs the Pro version.

Other apps from Trudelta

• Heat Stress+ gives more detail on risk in hot and cold weather, with guidance on activity and the likely effect on performance.
• Temperature Record records an estimate of core body temperature during an activity, along with WBGT and apparent temperature.
• Health Dashboard is a similar watch face for people who do not run, with an overall fitness rating built from five categories.

Quick answers

What is WBGT?
Wet bulb globe temperature is an international standard measure of heat stress on the body. It combines air temperature, humidity, wind speed and solar radiation, and is officially measured with three thermometers: a dry bulb, a wet bulb and a black globe. Acclimatised athletes feel less heat stress at the same WBGT than those who are not.

What are active MET-hours?
One MET is roughly the energy the body uses at rest. Walking uses about 4 to 5 METs and running 7 or more, depending on pace. Active MET-hours add up the energy used above rest over a period, accounting for both intensity and duration. Ready to Run counts all activity, including movement that was never recorded as a workout.

What is the acute-to-chronic workload ratio?
It compares the distance run in the last seven days with the weekly average over the last four weeks. A value between 0.8 and 1.2 is generally seen as the right range, and above 1.2 suggests the load is rising faster than the body may handle. Trudelta prefers it to Garmin’s Acute Load figure, which has no unit and is hard to read without its trend graph.

Which Garmin watches support Ready to Run?
Almost every Garmin watch that runs Connect IQ apps, except models roughly ten years old or older.

Is Ready to Run free?
Ready to Run is on the Connect IQ Store, and the red, amber and green colour coding is part of the Pro version.

Related reading

• CORE 2 body temperature sensor review
• Garmin Training Load explained
• GMT fixes the Garmin second time zone that goes wrong

Author: Ken, developer of Ready to Run, edited by the5krunner.

If you enjoyed reading this, here is another in the Indie Spotlight series: Runsense is a running coach that asks how the run felt.

Last Updated on 15 October 2026 by tfk the5krunner

tfk the5krunner

tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID