For anyone looking at running with power, here’s a brief summary of my move away from focusing on pace and how it went on my marathon run at Challenge Roth.
In a nutshell, I have switched for some time now to running with power rather than pace or HR measures. I was one of the first to grab a Stryd Pod three years ago now, though only really committed to it during my recent 18-week marathon training in advance of the Challenge Roth Triathlon. Why? Simply put, keeping a consistent energy output, regardless of all other external factors such as wind, hills, temperature, humidity, etc. is, when you stop to think about it, way more logical, to not say way easier, than attempting to hold a constant pace or monitoring the constant fluctuations of one’s heart rate. Yes, this means my pace with fluctuate regularly during any race — most especially on a hilly course, but this in no way means my race time objectives are in jeopardy … in any way.
Ok, so the basics are simple really. As one’s running fitness increases over time with training, one should, of course, be able to run faster, and longer. No big reveal there. So what do people do? They “up” their pace zones accordingly and start running faster paces in training. The problem with this is that pace is greatly affected by EXTERNAL forces applied to a runner (heat, humidity, hills/elevation gain, wind, etc.) If one wants to keep the same pace going up a hill as running on flat terrain, an increase in energy output would be required. The brain might be thinking it’s the same pace, but the body needs to work harder. Period. If one always ran in a vacuum, in optimal cool-ish weather, with no wind on perfectly flat terrain, I suppose attempting to hold a constant pace could be argued as useful and doable. But the reality is that matches get burned way too easily when attempting to hold the same pace as hills or headwinds arise. Yet, we keep the same pace. Why? Simply put: the ego is afraid to miss our time target. That, and we’ve never been told otherwise. And because we did not have reliable tools to measure power output before.
In comes running power pods (just like with cycling power meters). Here again, as one’s running fitness increases over time, (calculated as “Critical Power” (CP) with the Stryd Pod), one’s ability to push or “output” more power increases. NOT pace, but the power one can generate. For example: if I push 250 watts on a hill, my pace will be slower than if I push the same 250 watts on a flat road. Same energy output (250 watts) that I know I can hold without busting, just a variable pace, given the external forces vary (incline in this case.) But does our little brain ever hate it when pace varies! In my case, my body can hold 250 watts claims my Critical Power (CP) measure. No worries there, so no stress. No panting and groaning, no burning of matches. I let those pacers run past me uphill, as I keep my power nice and even, despite my pace slowing on the hill. But guess who I see again later in the race, running on empty tanks, slowly reeling them in as their pace slows? Yep, those same runners who blew by me going uphill.
Were I to try to keep the same pace when a hill arrives, I’d likely go well over my power output goal, to say, 350 watts. Just for the sake of arbitrarily holding a steady pace/speed metric. Makes absolutely no sense! Power output is an INTERNAL metric that, when held constant, is easy to hold. Again, my running fitness score (CP) tells me so, based on past training. Pace, on the other hand, when held constant, despite external forces against you (elevation gain, wind, etc.), is literally a crap shoot. When you keep to your targeted and known output of energy you know you can hold (watts), you will end a race distance (say a marathon in my case a couple of weeks ago), exactly on an empty tank. With no gas left. Not too little, not too much left. Just right on empty. Which is exactly how races should be paced … uh, I mean how energy should be expended on a run. No “rats, I could have run harder” feeling at the finish line and no wall hitting at km 30, 35 or 40, having burned too much power output by holding an arbitrary pace number obstinately, regardless of external forces/conditions. But wait, one could simply run slower paces when going uphill or facing harsh winds, right? True. That would be akin to managing your power output though wouldn’t it? With a Stryd Pod, you can keep an eye on your watts though, not ballpark your pace, hoping for the best.
When I run more in training and basically become a stronger runner, my CP score goes up in the Stryd app. Automatically. Very cool by the way. So when Stryd tells me my CP has increased to, say, 300 watts, it basically is telling me I am a stronger runner. Period. I then enter in the online “Race Calculator”, the time I want to achieve for any given race (and here, I entered the Challenge Roth Marathon course GPX file, with elevation gains therein, the race day temperature and humidity) and it tells me simply, OK Marc, just hold, for example, 267 watts constantly throughout the race and you’ll finish it at the exact time you are seeking. Flats? Hold 267 watts, please. Hill coming up? Hold 267, please (here, my pace takes a hit of course, making the hill easier to run). Running downhill for a bit? You guessed it, hold 267 (and yes, my pace will get faster there for a bit). I can even play around with the numbers. I want to run a particular course, with an estimated elevation profile, temperature, humidity and even sea level elevation at a faster time? Stryd will tell me how many watts I’d need to hold. More than 86% of my CP? Then it’s on me if I blow up in the latter stages of the run. Stryd recommends a wattage (86% of your CP), but you’re always in charge. Intuitively too much, based on recent runs and/or injuries – like it was the case for me at Roth? Then I scaled it down from the suggested 261 watts to 250 watts (closer to 80% of my CP). I even planned on lowering it to 240 and then 230 watts if my planar fasciitis was too painful (yes, in comes Perceived Rate of Exertion (PRE) and common sense, for one should never forgo gut instincts ever). What was cool is that the Race calculator told me what my finishing times would be if I were to hold an average wattage of 250, 240 or 230. Again, cool.
But does it work? At Roth, I saw runners desperately trying to hold their pace going up hills and when the sun started baking us on the dirt path by the canal. In virtually all cases, I passed them by soon enough, either on the downhill portion of a hill or later in the race, as they ran out of matches and started walking the latter hilly portions of the course, or slowed drastically even on flats. Or started walking … you guessed it… as I kept to my power target. I never once looked at my pace. Ever. I had my 250 watt target to hold and that was the only metric on my watch’s screen I set and looked at regularly. Sure, I was slightly disappointed in the early going, that I had to slow down, as I felt that I could have easily held 280 watts for almost the entire first 10K, but trust the system I did. I slowed and held my 250 watts. And again, disappointed slightly when hills came up and my 250 watts looked like a light jog sometimes compared to others holding constant paces, but I controlled my ego and passed those same pace speedsters, running on fumes later.
How did I end my first ever marathon distance in my life? Right on empty, as I crossed under the finishing arch. Not even close to bonking at 35K.
Aside from owing most of my first marathon training journey to my loving partner who trained by my side for 18 weeks, keeping a constant eye all race on my energy output, to not go too quickly, too slowly, bonk or finish with too much gas left in the tank, allowed me to race what for me, was a perfect race. How could anyone ask for more? I started running just a couple of years ago, having never run any distance at all really and despite injuries that kept me sidelined until race day at 59 years of age, I feel like I ran a perfect race. No bonking. Felt tired of course, but great after and recovered quickly the next day. My time might be far from elite status you might say and you’d be correct, but I could not be more thrilled. It was even a Boston Qualifying Time for me next year I was told.
As for time estimates using the Stryd Race Calculator, is it just a gimmick? Can its algorithms really estimate a race-finishing time with any precision? Well, Stryd estimated (by +/- 5 minutes) that if I held an average of 248 watts throughout the race (slowing on hills to not bust too early and speeding up a bit on downhills), I would complete the race course, with its inclines as per it’s GPX file, at 28 degrees Celsius that day, at 50% humidity, at an average of 354 metres of elevation above sea level, in the time of 3:46:52. How does that compare to my actual finishing time? 3:47:54.
Yeah, I think it works.
For more information from Stryd on How to Predict the Finishing Time of Your Next Race with Stryd, check out this video.