How does my weight setting affect my running power?
When training with power, it is vital to understand that running power devices (like Stryd, Garmin, Polar, or Suunto) do not measure absolute power (watts) directly in the way a bicycle power meter does. Instead, their sensors measure accelerations and forces to estimate your relative power, or 'watts per kilogramme' (W/kg).
Consequently, to display absolute power (watts), the device multiplies this W/kg estimate by the body weight you have configured in its companion app or user profile.
Why this matters for Artemis 3
Like all current running power devices, the Artemis 3 engine works internally using relative power (W/kg). It then converts this to absolute power (watts) for display.
When analysing a run, the power data received by TrainAsONE is in absolute watts, so TAO has to convert this back to relative power. Commonly, the weight used during the recording (to convert from relative to absolute on the device) is stored along with the recording, which TAO uses for the calculation. If not, TAO reverts to the weight in your TrainAsONE user profile. (Note: For Stryd users, there is an additional 'Stryd weight' setting in TrainAsONE that you can manually keep in sync with the weight entered into the Stryd platform).
Because the reported absolute watts are directly tied to this weight, changing your weight setting will change your power numbers for the exact same physical effort. If you update your weight, your historical absolute power data will suddenly be on a different 'scale' than your new data. While Artemis 3 is designed to adapt, frequent or large changes to your device weight setting can disrupt your power reporting and targetting in the short term.
Device-Specific Advice
Because of this mathematical relationship, how you manage your weight setting should depend on the device ecosystem you use:
Stryd Stryd officially recommends that you set your weight once and keep it constant. You should avoid updating your weight for minor, day-to-day fluctuations. Only update your Stryd weight setting if you experience a significant and permanent change in body mass (e.g., greater than 5%), and be aware that doing so will shift your baseline power numbers.
Garmin, Polar, Suunto, and COROS These watches calculate running power using the body weight stored in your general user profile. Many runners like to update their weight frequently in these apps (often via smart scales) for health and fitness tracking.
You must be aware that frequent weight updates will cause your running power numbers to constantly shift, even if your actual fitness and running form remain completely unchanged. For the most stable and consistent power data in TrainAsONE, you may want to consider limiting how often you update your weight in your profile, or at least be mindful of the artificial fluctuations these updates will introduce to your power data.