Signs of Arrhythmia in heart rate data
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The research
Since its first release Crickles has had a measure called Regularity that is calculated on all activities with heart rate data. This measure serves two purposes:
- In some cases the heart rate data indicates an obvious recording error. In such cases Regularity is reported as Check_Strap. Sometimes this can be fixed by simply changing the battery in the heart rate strap, if it’s a chest strap, or sometimes the strap itself may need replacing.
- In other cases there are jumps in the heart rate readings that are not obviously just errors and that are classified as Irregular or Unclear.
Some years ago we found from analysis of data of users who also completed a short heart health survey that a high occurrence of irregular readings in cyclists was correlated to a very high degree of statistical significance with heart rhythym issues such as atrial fibrillation. Mark, the Crickles cardiologist, has observed that this is consistent with the fact that ectopic beats, though not intrinsically worrisome, can sometimes presage the onset of arrhythmia.
A full description of this methodology and the findings is now available on the Research menu of this website here.
The technique for flagging irregularity described in this paper, which is used in Crickles, is a method that is extremely cheap to compute. Subsequent to this paper, the post-graduate mathematicians Jack Buckingham, Andrew Nugent and Yi Ting Loo at Warwick University analysed more sophisticated approaches to irregularity measurement. Their research corroborated the association between irregularity and arrhythmia. While they didn’t improve upon the predictability of the Crickles measure, they did lay out the matter extremely elegantly for future researchers. This paper is now also available on the Research menu here.
If it is indeed feasible for cyclists to get a pre-symptomatic warning of a potential propensity to arrhythmia obtained entirely from rides that they are already uploading to Crickles this could be a valuable pormpt to see a GP or cardiologist.
It goes without saying that the regularity indicator is not a medical diagnosis and an absence of irregular readings is certainly not a clean bill of cardiac health nor a guarantee of reduced risk.
Seeing your Regularity info on the Navigator
The easiest way to see the Regularity readings for your activities on the Navigator is on the Timeline page. Here, each activity point has a dot in the centre for any value of Regularity other than Regular. If it’s Irregular the dot is blue, if it’s Check_Strap the dot is black and if it’s Unclear the dot is grey. The value of Regularity is also shown on the tooltip. Here’s an example of an Irregular activity:
The Regularity value for each activity is also given on the Activities page. Remember, Regularity can only be derived for activities where heart rate data is available.
A count of Regularity values over all the activities on the Timeline page is shown at the top left :
While those experienced in modelling can in principle apply this count table to the model described in the Detecting Arrhythmia paper, Crickles does not currently translate the counts to a risk rating. The classic version of Crickles had an Irregularity page that addressed this; a revised version of this page may be reintroduced if there is user interest and I can think of way to make the presentation of data more intuitive.
Helping Crickles quickly for free
To take this research forward we need to know which Crickles users have been diagnosed with a heart rhythm problem and which have not. You can tell us this on the Profile page, where the question of whether you have had a diagnosis of an irregular heart rhythm defaults to Don’t know -
To tell us whether or not you have actually had a heart rhythm issue please hit the Edit Profile button and replace Don’t know with either Yes or No. Seasoned Crickles users who have previously completed the short heart health survey should find that this is pre-populated. In future we may add fields for capturing additional information comparable to that from the survey but for now if you could complete this Yes or No field it would be most helpful.