Archers' heart rate on TV: Bornand 2013 paper

The paper tells how the sensor came about that World Archery used in 2012 to show archers' heart rates on television during competition. It is not a study with data: the observations on heart rate are the engineers' impressions, because the signals were not recorded. They include one archer who, in a match of four three-arrow ends, went from about 60 beats per minute to 80 after the second end, 100 after the third and 120 after the fourth; heart rates that jumped when the opponent made a poor shot; and readings below 50 but also a few above 100. All athletes but one agreed to wear the sensor.

The federation had ruled out any hard object on the torso, the arms or in the hands, so an ultra-wideband radar with an antenna on the chest, which gave good results, was dropped. The solution chosen was a photoplethysmographic sensor, which reads changes in blood volume in the tissue using near-infrared light, strapped below the knee with an elastic bandage, with a battery and two radio links, one for the television production and one for the person fitting the sensor. It was tested in Nîmes in February 2012 and used at the World Field Championships in Val d'Isère and at the World Cup Final in Tokyo in September 2012. The prototype was built in four months from off-the-shelf parts.

There is no sample, no comparison with an electrocardiogram to show how well the sensor measured, and no recording: the authors state that they did not save the data and so could not replay the measurements. All the observations on the archers, including the idea that some looked pale in the morning because of their mental preparation techniques, are the authors' anecdotes or guesses.

For an archer the paper's value is historical: it explains where the heart rates shown on screen during live coverage of major events come from, and why the sensor sits on the leg rather than the chest. That heart rate climbs during a match and reacts to the opponent's shots is plausible and in line with other studies, but here it was observed by eye, without data, and the paper says nothing about how heart rate relates to score.