On the TomTom runner watch (the older one), press down to bring up the menu, down to highlight sensors then right to select this. Then it will show you a new menu saying Heart press right and then you can turn it on or off.
We don't know whether he watch is the first or second model so it is possible that he could and did turn this off (but you cannot turn off cadence).
Earlier a poster saw a light flashing on the watch that means that it would be the second model, but as he has two watches it is possible that one of the watches would still be the first version and so without the heart rate data. (Assuming you cannot turn off the heart rate on the second version - I do not know if this is true)
According to his Facebook, he received a TomTom in August 2014.
August 13, 2014 Â·
Thank you very much â€ª#â€ŽTomTomBoyâ€¬ Sam Cousins (& Ricky Wood @ Up & Running East Sheen for the intro) for making all the effort to visit, run & supply me with a â€ª#â€ŽTomTomâ€¬ Runner Cardio GPS & Heart Rate Monitor last night.
This device will help Dr Courtney Kipps & his sports / medical science experts @ http://www.iseh.co.uk track my heart rate data & also help me upload my running data much easier.
Alistair Parkes Thanks Sam at TomTom (& also Ricky at Up and Running, East Sheen. We really appreciate use of your "highly accurate, innovative technology" to help us share Robert's heart rate & running information with Dr Courtney Kipps, consultant sports physician at UCL's Institute of Sport, Exercise & Health (ISEH) - who's also the assistant medical director of the London Marathon and medical director of the London Triathlon. See: http://www.iseh.co.uk/consultantdetails/p/9/Courtney-Kipps Through pushing himself to his physical limits, Rob has also become a person of scientific interest to Dr Kipps and his ISEH colleagues, Bruce Paton and Dr Phil Hennis, who are working with Rob to assess his pain thresholds, improvements in VO2 Max and other physiological tests. They will continue to monitor his physical levels throughout his marathon journey.