A unique situation, what to do?

Hey everyone.

Last week (Thursday to be precise) I went for my usual 10k tempo run at the gym (8.6mph). As per normal, I wore my Garmin and my HRM.

Started off ok, and after about 10 - 15 minutes I noticed that, although my legs were feeling like they were in a tempo run, my heart rate was showing that I was barely pushing past 150bpm (75% of my theoretical max). I pushed on to 3 miles, expecting it to level out at about 165 (as it normally does) but instead it stayed at 150 the entire time.

I put it down to a discrepency on the day and went out on the Friday for a 5 mile run. At no time during that run (I was doing about 7.2 - 7.4) did my heart rate get above 145. My long run on Sunday (12.25 miles in 1hr 38, my fastest by 90 seconds or so) resulted in an average of just 144. 

I'm certaintly not complaning about this whatsoever (hell, I can run faster nowimage) but I'm a bit concerned about the harder efforts. I'm worried now that I need to push harder  on my tempo runs and speed work to get the aerobic benefit, however if I run too hard then my legs will just burn out. However, if I stay at the speeds I am now then I won't be improving any quicker and will eventually end up chasing my tail. 

 Does anyone have advice for a confused Duck?


  • How did the runs feel - sometimes failure to get your heart rate up can be an indication of overtraining - but if you felt fine on the run then it's probably not that.    Are you sure your HRM doesn't need a new battery?
  • I'm pretty sure it's not the battery - only got the monitor in August so unless there's a problem with it then I'm sure it's not that. I did check my resting heart rate to see if I was overtraining, but it's no higher than normal.

    In terms of how I feel, I feel fine - like I'm on a recovery run most of the time when I run at the pace I normally do (about 7.2 on easy/normal runs).
  • The strap can kind of fail in this way - especially if the rubber seal-ring is leaking sweat in - I have the same problem currently, and I haven't fully diagnosed the fault, but I've found internal corrosion but have yet to try a new battery or belt. Try scrubbing salt off the back, check the internals in the battery compartment, etc.
  • Thanks Steve, just had a look in the battery casing and at the battery/intenals it/themselves, and it looks perfectly normal - no discoloration or moisture on the battery or the contacts at all.

    I'm making a tendency to do the classic heart rate test - 2 fingers to the neck etc - and the readings (both on the Garmin and my very rough estimate) do seem to match. This is very confusing - I try to run to heart rate as often as possible, so if I was running to a malfunctioning monitor I reckon I would be feeling a little tired/burnt out by now, but I'm feeling just normal and this has been happening for a week and a half or so. 

  • (OK in my case the battery had discharged itself by a faulty seal and a bit of sweat getting in - a new battery fixed it. It was odd that in its death throes the old battery could pulse enough to show 30-50% of max, but no more.)

    In general all I can add is: if you perceived exertion or leg effort feels too high in relation to heart rate, it's because you haven't recovered enough from the previous session or you are generally overtraining or piling on the load too quickly.

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