Consistent issue with HR spiking after approx 7 to 10 minutes on 935

My very fit and competitive 12-year old runner experiences a consistent issue where her Garmin 935's HR data show a dramatic bump up at around 7 to 10 minutes into what is an otherwise easy (5/10 effort) long run, and then stays high. It does not correspond to her perceived effort at all. Any ideas? This is happening both when worn by itself as well as when using a chest strap.

At the same time, the Performance data doesn't kick in until right after this big bump. Is that by design? 

Parents
  • I'm convinced that its the HR sensor being tricked by arm movements/cadence. I've got several runs where my heart rate will jump to a value suspiciously similar to my cadence at the time, and then either self correct or continue to the end of the run. Tightening the strap seems to help - stopping the watch moving in my wrist. It's is annoying because it has impacted my reported VO2 max - because the watch has recorded a HR 170-180 when it was actually 130-140 for an easy run.

Reply
  • I'm convinced that its the HR sensor being tricked by arm movements/cadence. I've got several runs where my heart rate will jump to a value suspiciously similar to my cadence at the time, and then either self correct or continue to the end of the run. Tightening the strap seems to help - stopping the watch moving in my wrist. It's is annoying because it has impacted my reported VO2 max - because the watch has recorded a HR 170-180 when it was actually 130-140 for an easy run.

Children
No Data