There is a new landing page on the Navigator – called In a Nutshell – that gives a quick overview of your essential Crickles information from the last four weeks. It’s in the form of three blocks. The first shows you your aggregate cardiac stress score over the period:

The question of how much exercise is optimal is largely a matter of judgement and part of the value of Crickles lies in determining a cardiac stress measure in a credible and consistent way so that you can meaningfully compare your volume of exercise with that of your peers. The big number at the top of this block – 3,019 here – is the sum of your cardiac stress score over the past four weeks. The colour of the block – red in this example – indicates how this value (3,091) compares with that of other Crickles users who are closest to you in age. This is also explained in the sentence at the bottom – in this example the value of 3,091 is “Higher than most age group peers”. The bars in the block show your cardiac stress score for each day, as indicated here by the hover tip over 29th October.

More information on the derivation of these values can be found on the CSS Factors, Relative CSS, Timeline, CSS by Sport and Activities pages.

The second block gives you information about the level of heart rate that you sustain during exercise, summarised in the Threshold Heart Rate number at the top (158 beats per minute in this example):

This threshold rate is determined by looking at your heart rate over different time windows – although it’s termed Lactate Threshold Heart Rate (LTHR) Crickles knows nothing about your actual blood lactate levels – and is expressed as an estimate of the highest heart rate you have sustained or could sustain for an hour. This changes adaptively over time along with your exercise. The chart on the block shows how your threshold heart rate has changed over the past four weeks. Again, the block colour and the text at the bottom indicate how your current threshold heart rate compares with that of your age group peers.

To drill into this further, the LTHR FTP page shows you the chart more clearly over a longer time horizon. Also, if you sort the Activities page by descending Intensity, any activities for which Intensity is over 100 will be where your threshold estimate increased. The HR Zones page shows you proposed training zones derived from your current threshold heart rate.

The final block draws attention to any unusual heart rate readings of particular kinds over the past four weeks. Often or usually it will look like this:

Occasionally though you may see something like this:

If you see the message shown here then there was something suspicious about your heart rate reading on the identified date(s) suggestive of a faulty strap. Alternatively, you may be alerted to one or more “irregular” activities. This is detecting a different pattern of irregularity in the heart rate readings. It is reasonably common to see one of these now and then; it is less common to see more than one in a four week period. For example, at the time of writing 3% of athletes on Crickles had two or more activities flagged as irregular in the last four weeks. This is not in any way a medical diagnostic and the pattern detected would not per se be judged medically significant. Moreover, the absence of irregular readings does not imply in any way a clean bill of cardiac health and if you are concerned about your heart health you should seek medical advice and not rely on Crickles as a proxy. Nonetheless, a high number of irregular readings is associated with a higher reported incidence of heart rhythm issues.

Details of probable strap issues and irregular patterns can be found on the Activities page. If you want to see the heart rate curve that triggered one of these readings, you can do so on the Charts page, if you have access to it. If you have completed the Crickles survey and want to see more information on how your frequency of irregular readings compares to that of others with and without arrhythmia, you can find this on the Irregularity page.

You may notice that the default date range on all pages for which date range is present has been changed from the past six weeks to the past four weeks. This is in part to make it easier to compare the information on the In a Nutshell page to the more detailed information offered by those pages.

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