The Power Massager Pro has a built-in temperature sensor allowing you to obtain baseline personal data pre, during and post treatment!  Locate the thermometer sensor icon on the under side of the grip. Press trigger to turn on the Power Massager Pro, then press front of device against your skin and press and hold the temp icon for 3 seconds and release.  It will measure and report on the LED screen the temperatures of the area measured. Optimal muscle temperature is above 90 degrees F and when the warmup tip you're using during therapy no longer feels warm, you are approaching optimal muscle temperature for safe workout or recovery!