Apart from the inaugural Clogher marathon on Saturday, there is another event taking place at the weekend with roughly the same number of competitors. The 40th London Marathon has an early start on Sunday morning with elite women scheduled to set off at 7.15.
The device, which makes an audible alert when the wearer is too close to others, will be worn by the 100 elite competitors and 500 event coordinators.
The race, 19 laps of a closed course in St James’s Park, screened from public view, is the first major marathon since the Covid-19 pandemic, organisers say.
The fourth-fastest woman in the race, 21 year old Ethiopian star Degitu Azimeraw, has been forced to withdraw after failing a Covid-19 test. She ran the second-fastest debut marathon time for a woman when winning in 2:19.26 in Amsterdam last October.
There will be no mass participation on Sunday.
However, 45,000 runners will run the race virtually, logging their runs on a dedicated app.