A precise interval workout in the forest

I’m often asked how I find my training routes while travelling.  I’ve discussed that a bit in the past in terms of how I research places to run/bike/swim.  But sometimes it’s not so much finding a place, as it is getting a specific workout done.

For example, yesterday I had an interval workout to knock out.  It had a number of segments, but the meat of it was 10x400m.  On a track, that’d be easy to replicate over and over again.  But, what if you were where I was – in the middle of nowhere?


Well, then it gets a bit trickier.  In my case I was back in lovely forested Apeldoorn for a quick 28 hour trip.  And while there was a track, it was some distance away by car.  Plus, figuring out whether it was open to the public and closing times seemed like even more complexity.  In general for me time is my biggest limiter.  So spending time getting a taxi to the track, then running, and then getting a taxi back just appeared as a giant time waster.

Instead, I’d simply make my own track in the woods.  The first portion of the workout was a 10 minute warm-up followed by a set of high-cadence drills, which then segued into a 5-minute build of intensity.  All of that I could do wherever the heck I wanted since none of it really required much consistency.  So I did the 10 minutes wandering around the forest:


And then the cadence drills and build I did on a running/cycling path, since the forest was a bit muddy.


Oh yes, did I mention it was alternating between pouring and sunny? Like a confused child that just couldn’t decide what to do:


So as for the 10x400m sets, I wanted something that was very repeatable.  Ideally it’d be flat and straight.

I wanted straight because it would make it more likely that my route was the exact same each time.  Plus, if you have really tight 90 degree twists and turns you’re more likely to both slow down and slip and fall (it was wet).

And I wanted it repeatable so I could compare each set.  By that I mean that while I could have simply run 5x400m in one direction and 5x400m back, I really wouldn’t be able to compare interval #1 to #9.

In my case I had seen a perfectly straight section earlier in the evening, so I started with that:


I then found two chunks of wood on the path and just moved them out of the way to form a start line and a finish line.  You can see them in the lower right of each photo.



As for measuring the distance?  Well, I used GPS for that.  I simply started it with my first interval and then when it hit .25 miles I pressed stop and called that my finish line for all future attempts, regardless of what the actual watch displayed for distance.

So why not use GPS for every attempt?  Well, you’ll get slight variations in distance – especially since I was in the forest and doing them under tree cover.  And for preset intervals, in particular for ones as short as 400m, it’s fairly important that you’re doing 400m each time and not doing 385m one time and then 410 the next.  As that sort of difference would realistically result in a swing of at least a few seconds for each set.  And as any track coach will tell you – a key goal of intervals is doing them precisely the same each time (whatever the value is).

Now, the only catch with my plan is that it turned out to be on a false flat.  A rather significant one actually.  All my even numbered intervals were downhill, while all my odd numbered intervals were uphill.  You can see this a bit in the elevation graph for that section (the grey part):


This means you’ll get slightly different values for evens vs odds, but since I was doing enough of them I could easily compare them across those sets.  So it wasn’t too big a deal to simply look at 2/4/6/8/10 and compare within ‘like’ efforts.

Which, of course is often another goal of intervals.  You ideally want to see how your body is reacting and dealing with the sets.  Depending on the goal of the intervals you might expect more or less increase in effort (heart rate typically) over the course of the ‘evening’.  For example, is interval #10 immensely harder to hit time wise than interval #2?

In my case, I managed to nail all my uphill intervals last night on the prescribed time (1:27/400m), with a few of the downhill ones being slightly faster by 2-3 seconds.  I ended up trying to keep the intensity on the downhill ones basically the same as the uphill ones, thus resulting in the slight time increase.


Finally, for pacing on a real (oval) track, I actually ignore GPS entirely.  Seriously, just don’t use it – it’s just not good at measuring distance and thus pace for the level of accuracy you want.  Instead, I just use the 100m markers and do math from there.  So if I had a 1:28×400, then that’s simply 22s per 100m.  Thus you’d hit the lines at 22s, 44s, 66s, and 88s.  Simple, right?

Out in the woods I was too lazy to mark off those sections.  So instead I just did lap pacing.  For that I use the lap time option on my watch to pace by.  This isn’t perfect of course due to the slight variations – but it got me in the ballpark of the pace I was looking for (approx 5:48/mile, or 3:36/KM).  And realistically after 2-3 of these I was able to pace by feel without even looking at the watch.

In the end, here’s what my little segment of forest looked like from a satellite standpoint:


All but one track was within a few meters of the running path (with one being a few meters beyond that), which isn’t bad sine I did some 14 passes of that section over the course of the night including some final sprints after the 10×400 set.  Not too shabby for the woods.

And, also, not too shabby for a nice solid workout in the evening after 5 hours of trains in the morning and then more work at the office to fill out the day:


Thanks for reading!


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  1. I do like the way you try and do your session where ever you are… if I’m on holiday I just try and run. But that said I only really travel every other year. Now if I’m required to pop away for a day or to work, I just do hills hills and more hills. Now what kind of hill runner would I be if I had your job?

  2. lin

    Based on your results/PRs, isn’t 1:27/400m slow for you?

  3. Steffen

    Hey Ray, nice to see you have visited Holland again. Beeing just started on the Garmin connect front, from which program is the ft/rpm/bpm etc combined graph taken? Greetz!

  4. aufruf

    Hey Ray, could you please give some more information on what kind of cadence drills you did / normally do? Thanks a lot and take care!

  5. remco

    Worth a note, that a GPS can not measure circles or turns very well unless it has a measuring interval of >10 times the moving speed per second. This is usually way outside the measurable error of GPS. Therefor use the timer/stopwatch for perfectly measured tracks (which are usually certified).
    Nice to see you enjoy the Dutch summer too Ray :D . (yesterday we had the coldest 19th of august since 90 years).

  6. David

    So when you aren’t testing a watch, and just recording for your own stats/info, do you always use the garmin fenix? Or do you mix it up with the 620 and ambit?

    • I was testing some stuff with the Fenix2, otherwise I normally use the FR620 if I’m not testing something.

    • David

      I saw this run show up on Strava from your Fenix 2, but it didn’t have any splits. Did you actually do the splits with a different watch? Or is this a GC->Strava issue?

    • I think it’s a Fenix2 GC > Strava thing. :-/

    • Mads

      With the fenix2 it seems the Uploader in Strava doesn’t catch the “Laps”. If you export from GC (TCX) and upload manually it will… This might be different with the 620…?

    • Yeah. There’s some issues in general with the Fenix2 and Strava. Some are Strava’s fault, and some are Garmin’s fault. For example, Strava can’t parse the Fenix2 multisport workout files. Meanwhile, TrainingPeaks can. That seems like a Strava thing (likely).

      On the flip side, the splits thing seems more Garmin focused since it works just fine on the FR620 but not on the Fenix2. I suspect this may be a team issue where the fact that their come from entirely different divisions. I remember bringing it up many moons ago, but it sorta faded off.

    • Simon

      Hi Ray, may I ask what are you testing with the fenix2 ?

      I just bought this watch based on your review and it’s spot on :D

    • Matt B

      Ahhh, crossing my fingers that it is a daily activity tracker function. (Despite the fact that you have stated previously that the hardware does not work in a low power mode for this)

      Start whistling if this is possibly correct.

    • Strava has alway had trouble with multisport workouts, at least as captured by my 910xt. I don’t think that’s a Fenix2 problem.

    • David

      Actually “recently” strava has been happily accepting my 910XT multisport workouts. (I even went back and re-uploaded some old ones that it didn’t handle so gracefully in the past.)

    • Derick

      I hope they get that fixed soon since I just ordered the Fenix 2 to replace my FR305….
      I decided to start over with running and started a couch to 10k program (even though I can run a 5k no problem and can technically run a 10k already) so I can focus on form and build up muscles properly. And of course, these programs are all interval based. I guess the most important thing is that they will show up on Garmin Connect, but still it would be nice if they showed up everywhere. Do laps show up on other sites, like TrainingPeaks?

    • Yes, no problems with laps on TP from the Fenix2.

  7. Sebas

    Not having a track to run on in my area, this post comes in very handy and just at the right time!
    Also when running in the woods I always get the feeling that my Polar RC3 is getting pretty inaccurate (based on feel) or is it just my imagination.What’s your experience with that and is there a way to validate a .gpx file afterwards?

  8. Tim Grose

    One thing I often do is if I am not entirely sure of an exact distance is run for a time not a distance.
    So say you normally average 75 for 10×400 with 60s just do 10x75s with 60s instead.
    The training effect will be the same and another advantage of this is that you could just do and out and back on a trail and see more of your surroundings.
    Of, if you wanted to run the same section each time, you could of course just do that as well.

  9. I know those are arrows on your chart, but they sure look like you’re flipping the bird to your intervals! :-)

  10. Some Garmins feature Autolap by marked position (910xt). It works within a couple of strides from the marked position on the oval.

    Thank you for the interesting & motivating post.

  11. hollyoak

    “So instead I just did lap pacing. For that I use the lap time option on my watch to pace by.”

    What option is that? On my FR610 for workouts I can set a range and it will buzz if I’m out ‘or back in) of that range and it can get a tad annoying.

  12. Troy Braxton

    Wouldn’t a foot pod help with getting a more accurate distance in the woods?

    • It depends. If the trail was full of switchbacks, then definitely. But for straightaways like I had, GPS is a better ‘long term’ bet. By that I mean that had I calibrated the footpod correctly before hand, then sure, the footpod would have been quite good. But since I don’t even bother with a footpod anymore*, I’d have to add it and calibrate it.

      *I don’t use it these days since I can get cadence from the wrist for all modern watches that I use, and if indoors, then I’ll put it on there. But I try to avoid treadmills as much as possible this time of year.

    • Mr Nofish

      While there is no question calibration would improve accuracy, isn’t the footpod more consistent than GPS?

    • In most cases, yes. Though, for me I don’t tend to see too many issues with pace stability (at least on my units), so it doesn’t bother me much.

    • Mr Nofish

      I was thinking about distance mainly, since you were concerned with having the intervals all the same length, a pod seemed a better choice to me, I see all kind of wandering about from GPS when I’m doing laps or taking a look at somebody else’s (track races are especially ugly)

      My solution would be to calibrate the pod and leave in on the shoe, but I suppose with all of your traveling a pod is just another extra part waiting to act up.

    • Steve

      During the winter, I do a lot of running at an indoor track, and ditched the foot pod when I got my FR 220. I then had instances of the internal accelerometer malfunctioning and losing a lap or more of distance when recording my runs. Have you seen that with the 620? I went back to the foot pod and haven’t checked whether the issue has been fixed in the updates since.

    • To some degree you’ll see wide variations in pace using WDR (Wrist based detection). Sometimes it’s very close, othertimes not. For tonight on the treadmill the distance reported was 7.5mi (watch) to 6.5mi (treadmill).

  13. matt

    I assume you rushed home and made each direction and new Strava segment? KOM for .25miles in each direction in the middle of nowhere….I think that KOM could last for a very long time.

  14. Hubert

    If you plan to workout in Fontainebleau, let me know :-)

  15. Sander

    Hi Ray,

    Funny too see dutch pics on your site. If you want a beach(the hague) run or need a track let me know :-). Interesting stuff keep it up as i always struggle a bit when i am on vacation. I use the wahoo app a tracker and my suunto to keep an eye on balance and my run. Thanks again for sharing!

  16. Gabe

    Hi Ray – did you run in college? You are quite quick. You podium often in your tri’s with I imagine a strong bike and run ?

    I’m averaging 7:15 min/mi for my 1/2 marathon run pace but I’m having a hard time breaking through that plateau.

    • No running in college (mostly because I didn’t go to college). I ran cross country my freshman year of high school, but then quickly realized that was a horribly painful way to spend one’s afternoon…and then didn’t run again for about 10 years (as in, no running at all).

      For me, the biggest shifts in my running came at two points. The first was the introduction of intervals into my schedule. And the second was when I got onboard with a coach that put some thought and planning into it.

    • VitalijS

      Ray, have you ever try dynamic training plans offered by 2peak.com and the like? Whats your thoughts on dynamic training plans?

    • No, I haven’t played with them unfortunately.

  17. Dr. D

    Ray – Interestingly, I had a similar interval workout where the middle portion comprised: 4 sets of 3mins at 6:30mins/mile followed by 5mins at 5:40mins/mile. With no local track, my challenge was finding the flattest piece of tarmac, so I ended up running slightly uphill for a couple and downhill for the other two.

    Now (I have asked this before :-)), I wonder if someone will ever come up with a Google Maps based tool where you specify an area, length of road and elevation change preferred. The tool would then highlight all roads/trails that meet your requirements.

    This would make it much easier for those of us who are not close to tracks but need a flat road/trail for speed workouts or hilly ones for hill repeats!

    • That’d definitely be cool. They actually just introduced a portion of that into Google Maps that allows you to select a bike routing based on whether there is (or isn’t significant elevation in it).

    • Dr. D

      I have seen what Google has done for bike routing, maybe it is a start of something along the lines of what I am looking for.

      If there any Google employees (or anyone looking to ideas for a runners elevation app) reading this…please take up the challenge :-)

      Happy trails..and many thanks for a wonderful blog

  18. Chris

    Ray, I love that you titled this as a “precise” workout. I work in an industry where the differences between accuracy and precision (and resolution) are crucial, and yet I see professionals miss such nuances all of the time! Although, I can’t say I expected anything less of you. :-P

  19. Andy Turnbull

    Hi Ray. Re 100m splits on the running track. I use my Finis Tempo Trainer from my swimming kit bag for this… It evens comes with a belt clip you can use to clip it onto your running shorts.

    The strange thing is, my running pace splits for 100m on the track are almost identical to my swimming 25m splits….

    Cheers, Andy

  20. Sander

    Hi Ray, interesting to see you trust the 100m marks from road construction workers better than a GPS watch. I might be interesting what equipment they use to measure the length of a road when building it.
    You didn’t choose the best place to run by the way :). Please drop me a line next time you have to visit Apeldoorn. I live there and am part of a very active triathlon community. There are different trainings virtually every day.

  21. Marc

    Hi Ray!
    Thank you for you posts and reviews :)

    When you log this track, your Fenix2 was using the firmware version 3.7 or a 3.8 beta?
    Garmin did an update (3.8) for the Fenix2 and some people says that improves the gps accuracy.

    I’m curious to know if this is the best accuracy of this little impresive device!

  22. Mart

    Nice GPS accuracy. Not.

  23. Ray, I’ve noticed when running on a track my forerunner 220 seriously overestimates distance–probably 0.15 miles extra per 400m lap on tracks out in the open without trees or other sources of satellite interference. Any idea why this might be? It underestimates most other distances especially under tree cover and on routes with lots of turns, which I understand, but would have expected it to underestimate track curves as well.

  24. So 0.15/400m is an exaggeration, but if you look at the workout below you see widely differing paces for 1200m repeats run in times only a couple seconds apart:

    I’ll have to look into resetting. Thx!