A major advantage of Crickles is the consistency of the Cardiac Stress Score (CSS) across different types of sport or activity. If you don’t wear a heart rate monitor Crickles still gives you a meaningful CSS value – and not zero – that is consistent with the activities for which you did wear a heart rate monitor. For the most common types of activity (running and road cycling) when you don’t have a heart rate monitor Crickles now estimates CSS using a machine learning algorithm that tracks very nicely to the CSS you’d get if you did use a heart rate monitor.

Also, if when cycling you sometimes use a heart rate monitor, sometimes use a power meter and sometimes use both, the CSS values you get do not swing wildly according to how you were instrumented on each day.

This consistency is crucial for aggregating CSS over many activities, as shown on the front page of the Navigator. It is equally essential when calculating Fitness/Fatigue curves.

There is a new report called CSS by Sport that leverages this consistency in a new way. It looks like this:


The left hand chart breaks down your CSS by Sport, or activity type. The period over which this is summed is defined by the Date range in the side panel, which defaults to the past six weeks. You can change this to be any period for which Crickles has your activities.

The right hand chart shows the hourly rate at which you accrued CSS during activities over the same period.

In the example shown, the athlete incurs more CSS per hour when running than cycling but nonetheless generated a lot more CSS over the period while cycling due to the number of hours in the saddle. This is detailed in tooltips that appear when you hover over the bars. For example, hovering over the Run bar in the left hand chart shows this:


We see that there were nine runs in the period, the total CSS from these was 451 and that this comprised 10% of the athlete’s CSS in this period.

Hovering over the Run bar of the right hand chart shows this:

This shows that in the period while running the athlete was generating 83.5 units of CSS per hour and ran for 5.4 hours. Hovering over the Ride bar would show a lower hourly rate (actually 74.9) but a far higher number of hours (47.1).

The CSS by Sport report is (only) interesting as and when you engage in multiple different types of activity.

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