Control Training Intensities
A power meter is the only device to take a direct measurement of intensity (rate of energy output). Heart Rate and GPS speed provide an in-direct sign of intensity, and have some limitations. Whilst using stroke rate as an sign of intensity is inherently flawed. For this reason, a power meter is the best tool for controlling and monitoring training intensities.
A power meter delivers real time intensity measurement, without lag. Power values are not influenced by environmental conditions, meaning intensity values can be compared from day-to-day.