This was my HR plot from my 945 (with HRM-Tri strap) last week. No idea why the HR suddenly jumps after 5 minutes, it was definitely under-reading in those first 5 minutes as that run was a relatively steady state effort.
This probably happens every one in 50 runs at a guess.
They make even more money on the
ink catridgesHR straps.Some people don't care for perfectly accurate HR records. Wrist based HR is 'good enough' for most people.
(My HR strap occasionally gives duff info too. Nothing is perfect.)