The heart rate vs power graph is a tool that is utilized to estimate your physical work capacity (PWC). PWC simply refers to the power produced at a given heart rate. The key portion of the graph is the diagonal line drawn that represents the probably power you can create at each heart rate level, based on data from the ride. This rate varies slightly from ride to ride, as efficiency level and physiological and environmental conditions affect your heart rate, but should improve as you gain fitness.

The ride points themselves are graphed and broken into time windows (color coded) in order to best understand how heart rate is affected by fatigue. In addition to viewing the individual points, this graph can be fully customized to manipulate how the data is displayed by changing values for time windows split by color, data averaging window size, and other aspects of the graph. 

Graph customization options:

  • Min X and Y axis: Adjusts the axes of the graph to create a better scale. I.e. if the lower portion of the graph is empty, adjust the y-axis up to a value just below where the plotted points begin.
  • Time Window: This allows you to manage the time buckets that the ride is split into. Once you have done this you can toggle in different time splits in the top right corner of the graph by simply clicking on the series name.
  • Window size: This is the rolling average window size used for heart rate and power. A smaller window results in more data points, while a larger window will create less.
  • Smoothing: Power and heart rate can jump around, so by altering the smoothing you can view your data with less spikes to give it a simplified appearance. In this example the smoothing is set to 10 sec. This means that we accumulate rolling average values every 10 seconds, and only write values to the graph for every 10 seconds.
  • PWC BPM: This allows you to set the physical working capacity estimate for a given heart rate. This will be shown on the graph, as well as listed at the top, where the numbers in parentheses represent the standard deviation for each axis.
  • Power: This allows you to tune the range of power values to be included in the graph, such as by eliminating very low or 0 values in power or high power values from sprints
  • Cadence: This allows you to tune the range of cadence values to be included in the graph and PWC formula, i.e. discard any values where the cadence < 50 RPM.
  • HR Delay: Heart rate doesn’t instantly change the moment you increase/decrease your power output, rather there is a slight delay. This is referred to as heart rate lag. To compensate for this lag you can alter the graph so that heart rate is more closely aligned with power output. For example, the default heart rate delay is set to 45 sec.
  • Connected: Toggle this box to connect the data points into a line.  The dots will be connected in a linear formation based on time of the ride, showing the progress of the ratio of HR to power throughout the ride. The point in which the power decreased in relation to heart rate is where you hit your peak work capacity.