I’m doing timed intervals on the treadmill (C25k). My watch is consistently showing my heart rate spiking a few minutes after I begin my first run interval (running pace stays the same). I’d expect my heart to increase more gradually. What is happening?

I’ve been repeating the same timed intervals workout on the treadmill for a few weeks now. For each workout, my watch is consistently showing my heart rate increase when I start running, but then it’s showing an additional steep spike a few minutes later. Since I’m on a treadmill, I can control my speed and I know my running pace stays the same when the spike occurs). Does anyone know why this is happening?

Top Replies

gaijin over 1 year ago in reply to 4810551 +1

4810551 said:
I know I’ll be getting a chest strap monitor for the holidays, so I guess I should just ask for it early and start wearing it now.

This^

All Replies

0 4970335 over 1 year ago

You're experiencing "cadence lock", the heart rate sensor is sensing pulsing from your footstrikes rather than your heartbeat.

Try to repositioning the watch, maybe higher on the wrist or the other arm. Maybe wear it tighter?

0 4810551 over 1 year ago in reply to 4970335

Huh, thanks! I just read up on it, and I’m sure that’s what’s happening. But just so I completely understand, is the HR before the spike what is accurate? And everything after the spike is likely what is the false info?

I know I’ll be getting a chest strap monitor for the holidays, so I guess I should just ask for it early and start wearing it now.

0 gaijin over 1 year ago in reply to 4810551

4810551 said:
I know I’ll be getting a chest strap monitor for the holidays, so I guess I should just ask for it early and start wearing it now.

This^

0 Andrew over 1 year ago in reply to gaijin

OHR is improving, but agreed can't beat an hrm if accuracy is needed.