So Many Metrics for Runners!

img_8951This morning, 57.7 percent of me was water. My resting heart rate was 57. And I averaged 184 steps per minute on my run.

Fitness tracking and wearables are a huge market, and you might even have a device on your holiday wish-list. Pretty likely when I mentioned resting HR, you thought about checking yours on the device on your wrist.

I’m a data junkie: most of my training is heart-rate based, and I have a Garmin Forerunner 35 plus a Garmin Index Smart Scale. But a lot of that data is logged, recorded, archived … and never used for anything.

So what the heck do all these numbers mean, and which ones matter? I talked to two guys named Matt who helped me sort through the data I’m collecting to help make me and YOU better runners.

Matt Ebersole is the coach of Personal Best Training, based in Indianapolis but with clients across the country. He’s been coaching for 25 years, and works with runners of all levels, from 6-hour marathoners to Olympic Trials Qualifiers. He also has the dubious distinction of being my coach. For this piece, we’re just going to call him “Coach”.

I also talked to Matt Fitzgerald, author of “How Bad Do You Want It” and “80/20 Running,” among other books and articles. He also coaches and writes for a number of running and triathlon publications. He gets to be “Matt”.

“I believe that many of the health and fitness metrics that runners are now able to monitor with wearables, apps, and other technologies CAN be useful,” Matt said, “Whether they actually ARE useful depends on how they are used.”

Heart Rate

If you wear a FitBit or other activity tracker, you probably have this data. If you record it frequently, it can be a great tool. An uptick in your resting heart rate can indicate you’re not fully recovered, or that you’re overtraining.

“But as with most numbers, people don’t pay attention to it until something is wrong,” Coach said.

Matt said his favorite app for monitoring training stress and recovery status is HRV4, which measures heart rate variability rather than just resting heart rate. The app uses the camera on your phone to measure your heart rate, so no sensors or straps are needed. (Current generation phones include both a camera and a light emitting diode, which can be used for reflection based bio-optical imaging. The technique is called photoplethysmography, or PPG.)

“What distinguishes it from similar offerings is that it is supported by reliable guidance on how to use the information you’re gathering about your body in order to train more effectively,” Matt said.

Iron Levels

Coach said knowing your iron levels, both ferritin and hemocrit, is really useful especially for female runners. Again, you need baseline data to make the most of this for comparison.

“I have some women who train well at 35-40 [nanograms per milliter (ng/ml)], but some who are over 100,” Coach said. “It makes me wonder what those women could do if they were at 100, too, though.”

This wide range points to the need to get your levels checked when things are going well — during a recovery phase, for example. Then, if you’re feeling run down in a period of heavy training, a check of your iron levels can be compared to past data.

“Ideally, we’d track that every two weeks or once a month,” he said. Obviously that’s not feasible for most people, but worthy of routine checking.


Measured in steps per minute, cadence is a way to measure the efficiency of your form. But before we say anything else about it, know this: any changes to your cadence should come from strength training and stretching — not by just trying to take more steps.

While it varies by person and pace, around 180 steps per minute is a general target. More and more running watches track cadence, but it’s also pretty easy to do with just a timer. For 30 seconds, count the number of steps you take on one foot, then multiply by four. If you’re bored on the treadmill, that’s a great place to check your cadence, and you can see how it increases at higher speeds.

Coach said a dip in cadence can be a predictor of injury, because it can show a runner is slipping back into old habits. Fewer steps per minute is typically an indicator of overstriding, and also increases impact forces on your legs and decreases forward momentum.

Matt is more hesitant. “Research has consistently shown that virtually any attempt to increase or decrease one’s cadence from what is natural worsens running economy. That’s because runners naturally adopt the cadence that is most efficient for them.” Cadence can change beneficially — “but it has to happen naturally as part of the subtle stride evolution that unfolds as runners keep running.”

If you’re really interested in understanding biomechanics and injury prevention, pick up a copy of Jay Dicharry’s “Anatomy for Runners.” It’s the one my physical therapist uses in her work, and it has a place on my nightstand.


img_8948Salty Running is very conscientious about discussing weight, and running isn’t a thing we do to be thinner around here. However, not weighing enough can hinder your training. Coach said one of his runners always runs poorly when she drops under a certain weight. As soon as she tells him she’s struggling, that’s what he has her check.

He also shared what I think is a genius, forehead-smacking idea: set your scale’s “0” to an arbitrary number — it’s not your actual weight that matters, it’s the trends in increases and decreases. Some fluctuation is normal, but trends one way or the other can explain other training issues, injuries, or illnesses.


I know I should get 8-9 hours of sleep per night, but if I don’t use an alarm that shows how many hours I have until it’s time to wake up, I won’t get enough. Same for having it logged via my Garmin. It just takes staying up a little later and getting up a little earlier and suddenly it’s Saturday long run day and I’ve had six hours of sleep the two nights before.

So for me, sleep tracking is a reliable way I can make sure I’m logging enough hours. It can also point to issues you might be having, like if you wake up frequently.

Remember, sleep is when your body recovers from training and fitness gains are made. If you’re not sleeping adequately, your training may be for naught. Sleep deficit can also weaken your immune system.

And two things that don’t matter at all

  • Pace on easy days. Coach said some runners focus on this as a measure of fitness — the faster you can run on easy days, the more fit you are. He recommends using heart rate as a key indicator for easy days and not worrying about pace at all.
  •  GPS and the Strava effect. To some extent, this phenomenon has existed as long as we’ve had any sort of watch. “I’ve even found myself doing this coming back from knee surgery,” Coach said. “I look down at my watch and feel like I have to speed up or I’m going to kill my average pace.” Accept it: nobody cares. (But it’s okay if you run three laps around the parking lot so you finish on a round number. No shame in that game!)


No matter what metrics you track, the most important part to remember is to be consistent and to have a baseline. Without a lot of data and without a measure of what your “normal” is, all of these metrics are much less reliable indicators of, well, anything.

What metrics do you track? Which ones do you find the most useful?

Started running in my early 20s and ended up running my first marathon 15 months later. Managed to break 3 hours in my 12th marathon. Pilates instructor passionate about the importance of your powerhouse in running and the mind/body connection. One husband, zero kids, mama to one Australian Shepherd.

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  1. Great post – thank you. I’ve already ordered the anatomy book you recommended and downloaded the HRV app – I know tracking that is important, but didn’t realize there was an app! I’ve just recently REALLY started paying attention to heart rate during easy runs, after training with a coach that basically ran me into the ground and spending the whole spring and summer injured. I am on my own now, and am trying to be hyper aware of indicators of injury/overreaching/etc. so I can address them before they become full-blown issues.

    Side note: I’ve been following your coach’s blogs, too, and he is full of good info – I’ve run IMM a couple of times, and followed a canned plan of his for the half a couple years ago and ran my best half ever. I was going to use his plan for the full this year, but see above re: injury. Giving it a go this spring, though.

    1. The book is great! Let me know what you think about HRV, too. I’ve had a great year working with Ebersole — in some ways the opposite of the coaching situation you described. I think a lot of us would describe him as overly cautious, which is exactly what most of us runners need! This year if you registered for IMM early enough, you had access to some generic plans he put together, too. Do you have a spring full in mind?

      1. I did get his canned plan for IMM full – I registered for IMM on New Year’s, so I got a SUPER DUPER discount. I was SO bummed (and angry) that I couldn’t run it. My spring full is the Albany (GA) Snickers marathon. Seems to be well-organized and has a high BQ percentage (but that doesn’t matter for me this time – lost too much fitness over the summer).

  2. This was really helpful, thanks! My cadence is really high (like 200 during a race) and someone told me I should lower it. But I wouldn’t even know or care what it was if my Garmin didn’t measure it.

    1. Might be worth it to count by hand sometime and compare — my Garmin seems to count a little higher than I think is accurate. 200 during a race doesn’t seem too crazy, especially since it’s using the accelerometer on your wrist to determine cadence, and in the late stages of a race, my arms do whatever they want!

  3. I love this, especially as a numbers nerd. I track a lot of things in my running ahead training log. I track my sleep each night. My runs. My time spent cross training. My time spent strength training. I also track the time I spend foam rolling/stretching, getting massages, seeing a chiro, PT etc. etc. I don’t use a lot of the information on a daily basis even though I track it. I tend to use it when something feels off, a string of a few less than great feeling runs etc. Then it’s so easy to look back and see if I have been lagging on sleep, or if I haven’t been spending enough time on body maintenance and that is why I’m sore or not recovering as fast.

    This year I bought a new watch that tracks heart rate and cadence. For the most part I don’t have cadence issues, so I will look at it but usually just scroll past it quickly. With heart rate I tend not to pay attention to it for workouts, I use it for my easy runs instead of pace. This has really helped me slow down on easy days and not worry about pace etc. Because like you said, it doesn’t matter on those days!

    I do not track my weight daily or very consistently. I have never truly had a complex when it comes to my weight but I have always been pretty hesitant to check it regularly and I’m guessing it’s my internal self preservation and knowing that if I started doing that it could take me down a road I don’t need to go. Instead I check my weight at the docs, or if I have a rough few weeks of training or bad runs- and my sleep and everything else is where it should be, I will check in with the scale to see if that is where the issue is. As much as I love numbers, I just feel like weight is one number that really isn’t overly important to me and I am happy to keep it that way.

    1. I log sleep and PT/chiro/massage, too! Using HR for easy days has definitely kept me out of trouble, although I use it for workouts, too.

  4. Great post! I track almost all of these things with the exception of cadence because you have to draw the line somewhere :p (seriously though – something I don’t think gets mentioned often enough in the 180-cadence discussion is that cadence depends on tempo. Mine’s 180+ at race pace, less on easy jogs…I wouldn’t try to make it 180 on an easy run.) Anyway, I especially agree with the point about not weighing enough. That’s been my personal experience: below a certain weight I don’t perform well in running or in life. I don’t actually track it but can tell by the way my clothes fit.