Arm

Having a watch with an Heart rate (HR) monitor is fantastic until you realise it’s counting 20 BPM too high, and then it’s far less interesting because it’s reporting a moderate workout as heart.

Plenty of heart rate monitors come as chest straps and that’s great if your workout starts and ends somewhere where it’s okay to strap on a heart rate monitor. In winter it’s also about convenience. It is complicated to remove five layers, to put the HR monitor on, and then start an activity.