Week 3: Heart rate training diary – HR starts making sense

While one PB got smashed, a poor performance inspired a moment of clarity…
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New to the diary? Let me bring you up to speed: I'm working on a training plan with Fitbit's ambassador and former Olympian Greg Whyte on how to use heart rate information to become a better runner. My big question is simple: it's all well and good having a heart rate monitor on your arm, but how do you use it to actually get fitter?

Last week you might recall being a bit of a false start with the heatwave that engulfed London – but as the temperatures eased, this week has been much better.

I decided to repeat week two of the training schedule this week, since my original attempt was ruined by the heatwave. This was because week three ramps up significantly, and I want to make sure my legs are prepared. And it was a week full of learnings…

PBs and me

The first run was a 45 min at LT, including 20 mins at AT2 (check that box over to the left for translations), which I have now worked out to be approximately 165bpm and 175bpm respectively.

Learning from the week before, I hit the road at 175bpm early on, and tried to scale back to 165bpm after 20 minutes. At 45 mins I still felt fresh and opted to carry on to 10K to see how my PB stacked up: 52:52 was the final time, a big PB and a win for heart rate training, too.

Looking back at my heart rate data, I found two interesting parts. Firstly, from the end of the run I now believe that my AT2 HR is closer to 180bpm, so I could have gone harder in the first 20 mins. I also found it very difficult to get my heart rate down to sub-170bpm after the initial blast. On the graph below you can see a dip in pace, yet very little change in heart rate. I'll be catching up with Greg about why this was.

Week 3: Heart rate training diary – HR starts making sense

Curiously, though pace dipped off after the initial 20 mins heart rate didn't

Going with intervals

Next up was five sets of 2 x 200 sprint intervals. The least said about this the better. I hate sprint intervals with a passion. The first few sets were easy and the two minute rest breaks seemed like an eternity, but four sets in and the rests seemed fleeting.

It was hard going and the run left me stiff in my hamstrings, something that took effect in the last run of the week: a 5K race. This 'race' had to be done in my local park, and was a solo run against the clock. I was sure it would be a PB yet it was over a minute slower than my best. My heart rate also escalated through the run gradually and I had little left at the end. The tiredness of four runs in a week certainly played into the time, and left me wondering how I'd cope next week with much more time on my feet.

Week 3: Heart rate training diary – HR starts making sense

Greg Whyte has been building a plan, and guiding me on heart rate

The breakthrough

But it was my second 45 minute run at at LT (165bpm), which was to cause the biggest revelation of the week. This is my base level marathon pace run, and the third of this dairy – it's the run that's going to be the focus of my MISO cycle comparison in week six, and the best indicator of my improving fitness.

But there was an issue: the week before the same run was hillier, yet I was 20 seconds per mile slower this week at the same heart rate. Why? The slower run was in the morning, could that be it? Was it what I ate the night before? Or drank?

And this is where heart rate training comes into its own. I had a revelation.

By training with heart rate, I could find the answers to these questions. Because heart rate is the constant, if I set up a spreadsheet (stay with me here) of my runs, I could try and find a correlation between when I was hot and when I was not. And that's how you really start to use heart rate for your training.

Week 3: Heart rate training diary – HR starts making sense

9:40 average pace was a whole 20 seconds slower than last week at LT

So I set one up. It's probably the geekiest thing I've ever done when it comes to fitness, but was it possible to ascertain the foods, times and preparation that correlated with my fastest runs? Well, perhaps by the time my first MISO cycle end in week six, I'll have the answers. I'll share it next week when it has a little more data.

But I'm now closing in on establishing my heart rate zones: 165bpm is LT, 175bpm is AT1 and 180bpm for AT2. My sprint intervals got me up to 190, which is a few beats shy of MHR. Getting a feel for these heart rates has taken a few weeks, but knowing the levels is helping to pace my training, giving me confidence about long runs and making my sessions more efficient. And if this spreadsheet thing works out, I may understand what powers my good runs, too.

So it's all good. But next up I have to tackle week three's gruelling schedule. Check in next time to see how I get on.

Check out our heart rate training series:

Week 1: Getting assessed

Week 2: Feeling the heat

TAGGED Sport Running

How we test

James Stables


James is the co-founder of Wareable, and he has been a technology journalist for 15 years.

He started his career at Future Publishing, James became the features editor of T3 Magazine and T3.com and was a regular contributor to TechRadar – before leaving Future Publishing to found Wareable in 2014.

James has been at the helm of Wareable since 2014 and has become one of the leading experts in wearable technologies globally. He has reviewed, tested, and covered pretty much every wearable on the market, and is passionate about the evolving industry, and wearables helping people achieve healthier and happier lives.

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