Quite a few takes on HRM's but my view is that I use it to bring myself up to pace- Too often I find myself below working level so will be slower than I could be and I am not working the body as efficiently as I could be to retain the fitmess that I used to have. Also use it so that I do not overdo it on rides so that I can finish the rides with just enough energy to ward off the hints that the grass needs cutting- and it also tells me that I should not have tackled that last hill that hard.
As to warning me that I am about to have a heart attack or the Heart has just stopped- Don't think it will do that, but as a training aid to keep me within my Heart rate parameters It works well.
So Computer- Cadence monitor and Heart monitor. Expensive but look at the Garmon Edge 305. Took me years to get one- and it is far better than anything else I have ever used.
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How long was I in the army? Five foot seven.
Spike Milligan