Validity and reproducibility of commercial cycling power meters in hot and cold environmental temperatures

Power meters are a training tool used to help cyclists improve performance by objectively monitoring intensity.  Some power meters are well established and validated, whereas others are relatively new.  Most power meters have been tested for validity and reliability in laboratory and field settings of similar conditions; however, the reproducibility of these power meters across different temperatures has not been established.  Purpose :  To examine the potential differences of the CompuTrainer, PowerTap, Stages, and Vector power meters in hot and cold compared to a room temperature environment.  Methods: Recreationally trained male (n=7) and female (n=3) participants each completed three incremental cycling trials in hot (33°C), cold (7°C), or room temperature (RT, 20°C) conditions.  The power meters were placed on a standard road bicycle and power output was logged and recorded.  Results: The CompuTrainer was higher in the room temperature trial compared to the cold and the hot, but not between the hot and cold trial.  The PowerTap was not different in RT and cold, but was lower in hot compared to RT and compared to cold.  The Stages was not different between RT and cold, but was lower in the hot compared to RT and compared to cold.  The Vector was not different between RT and cold but was lower in the hot compared to RT and compared to cold.  Conclusion: These data indicate that environmental temperature may affect the reproducibility of power meters.  It is important to recognize the potential differences between temperatures when choosing a power meter.