Pacing a trail race | 80/20 Endurance

Pacing a trail race

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    As a newcomer to trail racing I’d value any views on how best to pace a trail race – not burning out too soon, but aiming to finish in a good time. For a flat road race I have a view of what min/km I would be aiming for over a 1 hour or 2 hour race, but this wouldn’t be appropriate for a trail race with varying surfaces, hills etc. In the absence of power data would it be best to monitor heart rate? For example aiming for a heart rate around lactate threshold for a race taking around 1 hour, but a lower figure (eg 90-95% of LTHR) for a race around 2 hours.

    If setting a target heart rate is it best to stay below this figure throughout or use this as an average over the course of the race? How would you deal with cardiac drift over the 1-2 hours – still keep below the target heart rate or accept that HR will rise during the race? Any thoughts welcome.


    I’m also interested in this as I have been focusing on trail racing for quite some time and I still don’t know if my approach is best. Here’s my experience:

    By Pace – This is almost never usable due to the terrain and surface variability. Rarely I’ll run a flat and smooth “trail” race and in those cases I’ll be able to use pace. Otherwise I like to use pace split goals only when I have run the course many times and have a solid and usable course file to go by.

    By HR – This is what I use most. Almost every reason that HR applies to other types of racing can apply to trail racing. Knowing your LTHR can help “back into” goal HR for almost any trail race. The one exception I can think of is high-altitude racing, like Pikes Peak Marathon/Ascent, where my experience has been that altitude depresses the BPM I can hit by varying amounts.

    By Power – I have run with a Stryd pod since early 2017 and I’m very familiar with the device. I think it has a lot of functionality…for road running. Unfortunately for trail racing, the extreme variability of the terrain makes it difficult to “hold” watts for the most part. And totally forget about it when the trail turns steeply (up or down) as it is just not designed for those situations. It’s also hard to just monitor watts while trail racing too as you need to focus on the trail so you don’t trip and fall!

    So that’s my experience, interested in what others have to say as Trail Racing is what I like to do most.

    Matt Fitzgerald

    For what it’s worth, the most successful ultrarunners race primarily by perceived effort. RPE is far more reliable than any empirical metric can ever be for those runners who are, or become, attuned to it. Race courses are so individual in ultra running that you really can’t really plan for any race you haven’t done already based on pace, power, or HR. Your best bet, actually, is to look at past race results, see how runners at your level have fared, and calibrate your expectations accordingly. Even then, though, being tuned into your body and what it can and can’t do is essential to optimal execution.


    Thanks for your comments Brian and Matt. RPE worked well for me on a shorter race, but in a recent trail half marathon I needed breaks towards the end – in retrospect this was when my heart rate was going above LTHR. Made me wonder if I’d have had a more consistent run if I’d controlled effort earlier.

    Brian – how do you set your goal HR for a race? This article may be of interest


    Brian – how do you set your goal HR for a race? This article may be of interest

    Basically the same way I set a goal for road races, based on what the goal time is of the event. For example, if I expect it to be faster than an hour, I want to be in my LTHR range. Shorter than an hour and I’m not as concerned about HR as I am with effort level. But the longer the race the more I am cognizant of HR for the reasons you stated. It sounds like you’re more interested in the longer races based on your comments.

    I’ve learned I am pretty poor at judging RPE myself which has gotten me into trouble at ultra events. Going out too fast in all the excitement of a race start will make a hard effort feel alot easier than it is. Then that hard effort early catches up to you later as you described. And then of course it is too late and you pay back that early time gained with interest later. Thus I like HR as a safety check in long events. I also use Power when possible (usually on long climbs).


    Thanks Brian

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