A bit of an odd question this one, but I thought I'd see if anyone can shed any light on it. I've got a Polar HRM which I use whenever I go out running. I don't use it to stick in certain zones at the moment, just to get a bit of feedback. With marathon training I've done most of my cardio as running outside so haven't been to the gym for a while.

Today I went back to the gym, and went on the treadmill which is Polar ready for a bit after doing some weights. The treadmill picked up a signal from the HRM chest strap because it was displaying something all the way through, but the figure on the treadmill was completely different to the number my wrist unit was showing - consistently 30 - 40bpm higher than the watch said, and at one point it said 206 while my watch said that I was somewhere in the 120s/130s.

I'll go with the reading from my watch as I'm sure I wasn't exercising at the intensity the treadmill said (I was walking, on a hard hill programme), but I'm just confused as to why the readings were so different when they were presumably both picking up the same signal from the same chest strap (no-one else in the gym seemed to be using a HRM so I don't think it was interference).

Very strange.

My first thought was interference from someone else ... but if that's not it, I'd guess that the machine readout is broken. With all the running you do, the numbers on your watch sound right and the 206 sounds way too high. I've certainly gotten some bizarre numbers from gym machines (like 68? 220? )

Strange indeed but I think you're right to go by the watch.

I always end up with interference from other people when I am at the gym using the treadmill HRM readout. I just stick to my wrist monitor which for some reason does not have interference issues even if there are other people near at hand.