Heart rate tracking is the great obsession of the wearable age. Most new devices can manage it, we obsess over its accuracy, but what exactly is the point of it? Other than gaining a bit of extra data from our workouts, why bother using a heart rate monitor at all?
We're told by the likes of Garmin and Fitbit that heart rate is the smarter way to train, but just what does that entail?
Essential reading: Best heart rate monitors
That's what this diary is all about. As I train for the Reigate Half Marathon in September, I've enlisted the help of Fitbit ambassador and former Olympian Greg Whyte. Whyte runs a high performance centre for elite athletes in Central London, and he's going to be helping decipher my data.
Aside from doing all the hard work, I'm also going to be testing heart rate tech and techniques to the limit as I prepare for the race. Does it work? Is it useful to my training? And just what effect does that training have on my heart?
So, this being week one of the diary, I'd better reveal a bit about myself. After being somewhat of a reluctant runner for a while, in the last year I've caught the bug. Not full blown running flu, but definitely a heavy cold.
I'm running the best I've done in years; injury free and feeling fit, it's time to kick on. Having struggled to break a two-hour half marathon (two 2:01s and a 2:03), I'm determined to make September's Reigate Half the best ever. But why stop at 1:59? That's well within reach. That's why I've set myself the near impossible task of gunning for a 1:45, and I need Greg Whyte to help me.
For week one, I went off to Greg's lab in central London. While I had more varied runs in my Strava, I wanted to make sure he had the most up-to-date data set possible to look at. Due to the amount of recent interval work I'd been doing, I didn't have a steady run from the last month, so I got up at 6.45 and ran a lap of the park immediately before the meeting.
But what would Greg see in my running data? Here's what he had to say:
"It's a nice run, pacing at 5.23/km which is good, in the 8/min miles. You have a peak at 176bpm but it's that average of 161bpm really that's important. That's what we're interested in because it's a snapshot. Take off the first few minutes and you have a square wave, and shows that you've held a pace that is comfortable and therefore a good snapshot of a single session."
Not so technical
I was kind of expecting Greg to get super technical about the data – or struggle from the lack of detail within the Fitbit graphs. But he was coming at things from a much more general standpoint, and what he was saying made sense. What he was looking at was my threshold heart rate – the effort in which you could run 26.6 miles.
"What you're interested in is target heart rates. Are you in the target zone? To do that you need to have a session outcome predetermined. So if it's a steady run at marathon race pace, then it's about making sure you achieve that.
"Then it's about profiling and looking at that session over time," he said.
"Have key sessions that you monitor, repeat every six weeks and see if your response has changed."
Greg went on to explain how you monitor those key sessions:
"What's critical is average pace. With heart rate, your marathon pace heart rate, which is threshold, doesn't change over time. What you're hoping is that you're running faster in that time. The average pace is all important.
"Heart rate is the global measure of effort. It says what you're doing. The external measure is how fast you're running, but those factors are affected by environment: how hot is the weather, how tired is your body. All those things affect your pace."
Essential reading: From couch to 5K with wearable tech
Greg said that it takes around six weeks to make a physiological change in your body, so if you want to see improvement, it's best to plan in key sessions to profile in that time. In professional sport that's called a MISO cycle.
"Sometimes it's complex, but it's about goals. In terms of the big goal, that's completing your race or event. At worst you want a three month run in, or even 12 months for a marathon. Then you set intermediate goals, which you're trying to achieve, and that's your MISO cycle."
So where do I go from here? Well, I know that 161bpm is my marathon race pace. Greg was drawing me up a plan to get in training for the half marathon, which I can then break down into smaller cycles. For now all I have to do is start running.
Read more next Monday to find out just how hard applying all this fantastic theory to real life training can be.