Cold morning sessions keep throwing my wrist HR off — last Saturday at 42°F it spiked into the 170s while the chest strap held steady at 138 on a 90-minute aerobic run. For building endurance and reducing overuse risk by keeping easy days truly easy, I’m leaning chest strap for zone control. Have you seen temperature or sweat affect accuracy, and which tool do you trust on long steady runs?
leaning chest strap for zone control. Have you seen temperature or sweat affect accuracy, and which tool Same here — in the low 40s my wrist jumps into the 170s in mile one while the strap sits about 138 once I wet the electrodes. Quick fix: dampen the strap before you head out and tuck the watch under a sleeve or over a thin glove to warm the sensor; wrist is fine for treadmill or summer easy days, but for 90‑minute aerobic runs I trust the strap.
Short answer from my side: I’m seeing the same pattern — one concrete thing that helped was writing down the exact handoff and timebox it to 15–20 min. Does that match what you’re running into?
Same here in “42°F” temps — my wrist shoots into the 170s in mile one while the strap sits about 138. What helps me is wearing the watch two finger-widths up under the sleeve with a 3–5 min warmup and wetting the chest strap electrodes if it’s dry. I still trust the strap for long aerobic days like your 90‑minute run, but if it chafes, a forearm optical (Polar Verity Sense/Scosche) is a solid middle ground, @OP.
@OP I trust the chest strap on cold starts, and the one thing that fixed early spikes for me was wetting the strap pads (or a dab of electrode gel) before heading out, then tucking it under a base layer so it stays warm. Once I’m 15–20 minutes in and warm, the wrist usually settles and is fine for steady runs.