If you do not have a smart trainer or a power meter, you can configure the app to report Virtual Watts, provided that your trainer is compatible. Virtual Watts is a calculated estimate of power exerted based on the speed from a speed sensor and a known power curve for a given trainer.
The accuracy of the reported power will depend on the accuracy of the power curve for your trainer.
For more information on how Virtual Watts are calculated: Virtual Watts
Generic Power Curves
If your trainer is not available on the Virtual Watts power curve selector in the app, please try the generic power curve that best matches your trainer (magnetic or fluid). There are some trainers where this still might not work very well. If you're using rollers, please select a set of rollers that best matches the rollers that you currently own.
Choosing a Level or Setting
If your trainer has different levels or settings, be sure to select one that matches the supported power curves in the app. (App setting and trainer setting should match). If you're running out of gears and not getting enough resistance, choose a higher setting. If you're getting too much resistance, choose a lower setting.
Ensure your wheel size is correct
Check that you've chosen the correct wheel size in the Virtual Watts settings in SYSTM, and also in the sensor's settings in its parent app. Choose the actual wheel size that you have on your bike, no matter what trainer you're using.