Runner on a hot day


Did you know that environmental conditions can have a big impact on your running intensity?

Most runners know it, but don’t take action to acknowledge it or to adjust their training.

If you use a Power Meter to set your training intensity, SuperPower Calculator for Sheets (SPCs) can adjust your Critical Power (CP) and/or your planned training or target race power for differing Temperature, Humidity and Altitude.

The impact of weather conditions

It’s harder to run on a hot day.

It’s harder to run when it’s humid.

And worst of all? Running on a hot, humid day at a higher altitude than you’re used to.

A real-life scenario: One of the runners I coach is based in Houston, Texas. Compared to conditions in February and March, Houston in late-April/May and through the summer is hot throughout the day and more and more humid from early afternoon into late evening. The runner was starting to struggle to complete workouts in May that he had no problem with earlier in the year. So we adjusted his CP (set in cooler, less humid conditions) for the changed environment – a 10W change that resulted in the workout targets being achievable once more.

Bottom line – it’s possible to take heat, humidity and altitude into account if you run using a Power Meter.

Stryd's Race Power Predictor

In April 2019 the Stryd team released the race power predictor.

This calculator enables you to enter a power (wattage) along with from and to environmental conditions (heat, humidity and altitude) and calculates a converted percentage and a converted power (wattage).

You can use it to convert your Critical Power (CP), or to convert a training or racing target power to account for different environmental conditions compared to those in place when you set your CP or target power.

Other ways to take account of the weather

Stryd’s calculation has been built into:

Still out in the cold ...

It’s possible to take heat, humidity and altitude into account.

But so far, I’m not aware of any research into the impact of direct vs. indirect sunlight (it may be harder to run in direct sunlight).

Do you know of any research or calculations that account for direct sunlight? Join the discussion (Facebook link below).


Feedback? Questions?

Join the discussion in the from1runner2another Facebook group.