Running with power: It’s marathon race day. You’ve tapered well, your legs are fresh and you’re ready to go. Last night you went over your pacing strategy and even wrote it on your hand but as you fly into the first few miles, all the adrenaline pumping through your veins makes you feel invincible. You’re running a little quicker than you’d planned but you convince yourself this faster pace is actually ‘easy’ enough that you’ll be able to carry it the whole race. Except you can’t. It’s a big trick. But by the time you realise, you’ve already paid the price.
Somewhere in the second half of the race, even though you’re running just as hard, your pace drops by a minute a mile. The balloons of your pace group flutter by and you brace yourself for the inevitable suffer-fest and a finish time that’s way off your personal best. Sound familiar? Thought so.
That’s because pacing the perfect race is tough, a puzzler that’s probably troubled runners ever since the original marathon man Philippides went all out from Marathon to Athens to announce the defeat of the Persians and collapsed and died on arrival.
We don’t know for sure because this is all stuff of Greek myth, but if Philippides is anything like me, he probably got caught up with how great he felt in the first six miles, went out far too hard and paid the ultimate price. It’s an easy mistake to make and one that thousands of runners have made since Big P left it all out there. But after 2,500 years or so we might finally have a solution.
There’s a new metric in town that promises to reign in the over-eager Out Too Fasts, put an end to the Mile 20 blow ups and lead runners everywhere smiling into the Promise Land of even pacing and personal bests. Welcome to The Running Power Revolution.
Running with power vs feel, heart rate and pace
Until now we’ve had three main methods for pacing a race. Way back before all the running tech arrived on the scene, runners ran on perceived effort (RPE) aka feel. But as we know feel has a flaw, in the race-day excitement it’s all too easy to think those easy early miles will just keep coming.
Then in the early Eighties the first heart rate monitors arrived and we had BPM readings to manage our effort. But there are a whole range of external forces beyond how hard we’re working, that can change your heart rate reading when we run,
These include the temperature, fatigue, stress, caffeine and even incoming illness. Your heart rate is all of these things and a slightly delayed sign of how your body is responding to the work you’re doing rather than the work itself. Therefore it’s also hard to run on a consistent heart rate, particularly on an undulating course.
What happened on the course was a bit of a revelation. I ended up running 1:31, my third fastest half marathon ever but the real surprise was how easy it felt.
Finally, in 2003 the first GPS running watch arrived and we could track the number that most of us are still slaves to on race day – real-time pace. But we all know how that can go. Complicated pace strategies, tricky sums deep into the race and of course, panic if the GPS signal fails.
They’re all useful but none of these are perfect methods for managing effort effectively. Luckily, now there’s another option – power. Long used by cyclists to help guide consistent effort, power has come to running thanks to foot pods such as the Stryd Power pod, RunVi’s smart insoles and Garmin’s Running Dynamics Pod.
I’ve been testing Stryd, a small sensor that weighs just 10g and clips to the laces of your shoes much like a race timing chip. It uses 3D micro accelerometers to measure the smallest movements – three-dimensional acceleration – and then with rapid computer processing and some complex algorithms it turns those readings into a power output number, measured in Watts.
How do I know what power to run at?
With a few benchmark stats (e.g. your most recent 5k, 10k, half or marathon times) or some easy-to-do baseline runs Stryd can calculate your Critical Power. This is the the maximum sustainable power output an athlete can maintain for a period of time.
You can then use Stryd’s race calculator to estimate the target power you will be able maintain for the distance you’re about to race. Whereas a target pace is a estimate of how fast you hope to run to achieve your time goal, the important thing here is that Stryd instead helps you to set a realistic goal, based on your current performance levels, and then tells you how to achieve that by running at a consistent, even effort that’s just below your threshold.
Putting power to the test
In my training runs I’ve tracking power rather than using it as a training guide, that’s a whole other area I’m yet to dig into. But I have run two races using power as my guide. The first was a two-day 100km ultra with 50k each day, the Race to the Stones, the second was the Runthrough Wimbledon Half.
In those tests I’ve found that running on a single number – the power target – has some huge benefits.
For a start having a realistic assessment of your performance potential gives you a confidence that you don’t get running to a target pace. There’s more certainty that you’re physically able to maintain the level of running required, from start to finish, to hit your goal. It’s a useful shift in race psychology with some of the doubts silenced.
The urge to run fast at the beginning of a race powered by the phoney feel goods is also eliminated, as are any concerns about high heart rate or BPM spikes that you can sometimes get during races.
During both races I’ve found myself running with my head up rather than glancing at my watch a lot. I don’t mean that entirely literally but for the first time in 10 years of running, I’m using race markers for a measure of distance, I’m not noticing half miles or increments as you might do glancing more frequently at pace on your watch.
In that sense using power is a bit like running on feel where you have a sense of being in control of the effort at a ‘comfortable’ level but an upper control limit that prevents your brain getting carried away.
Running with power: Half the battle?
The Runthrough Wimbledon Half is a reasonably hilly, trail half marathon. The day I ran this race it was very hot with temperatures ranging from 25-28 degrees. On the morning of the race I wasn’t up for it at all, in fact I wanted to bail out and stay in bed. I felt groggy, heavy and I went into the race thinking it’d just be a steady training run.
But I also thought it’d be the perfect opportunity to see what running on power in a shorter race would be like. So I crunched the numbers in the Stryd app and according to the race pace calculator my half marathon power target was 308 Watts. Because of the hills and the heat, I decided I’d drop that slightly and set off to run at around 295 Watts.
What happened on the course was a bit of a revelation. I ended up running 1:31, my third fastest half marathon ever but the real surprise was how easy it felt. I was in complete control from start to finish, not a single runner passed me on the course and for the final three miles, when I’d usually be really fighting the race, I was able to step up a gear. Because I dropped my power on the hills they felt easy-ish and despite a drop in pace on these inclines, because I wasn’t busting my threshold I had more to give on the flats and so it didn’t cost me over the course of the whole race.
According to Stryd my average power over the whole 13.1 miles was 306 Watts, so I ran a little lower than Stryd’s suggested target but a little higher than my own revised target.
But I also had one of the most enjoyable runs ever. I ran fast and without the suffering that usually comes with it. Could I have suffered a bit more and clocked a better time? Possibly. But I could equally have run faster, suffered more and clocked a worse time, absolutely. There’s a feeling with Stryd that you run the race you deserve not the race you think you deserve. You don’t bank time and you don’t get sucked into a false sense of ease.
Now I’m not saying that power meters have all the answers but I’m definitely intrigued to see what happens when you take it to a flat, city half or full marathon where the consistency of terrain should, in theory at least, make this an even more potent weapon on the battle to run the perfect paced race.
Now read this: Powering my way to back-to-back 50k PBs
