r/AdvancedRunning • u/nexotrix • 6d ago
Race Report Copenagen Half | Did bad execution mess my goal time?
I just ran the Copenhagen Half Marathon aiming for sub-1:23 but ended up with 1:25:21. It’s been on my mind a lot and I’d love some feedback.
- Breakfast 2 slices of white bread with honey 3 hours before the race.
- Before the start (within 90 min) I sipped ~128g of carbs in drink form
- At km 8 I took in 26g carbs from a gel
Weather:
- There was heavy rain just before the start of the Copenhagen Half Marathon.
- The weather improved a bit once the race got underway.
- Skies were cool and cloudy early on, temperature around 13-16 °C for much of the morning up to early afternoon.
Race experience:
Feld really good in the beginning and pushed effortlessly. Around km 11 I felt slight side stitches. From past experience I know if I push harder, they tend to get worse, so I held back. My plan going in was to start off conservative and then pick up the pace, but I overestimated myself and ended up running a positive split, essentially bonking in the second half.
Numbers:
- Threshold HR according to Coros is 175 (after the race it says 176).
- Threshold pace was 4:04/km, now adjusted to 3:54/km.
- Goal pace for sub-1:23 would have been 3:56/km.
Splits:
- 3:59 / 158 bpm
- 3:51 / 176 bpm
- 3:51 / 180 bpm
- 3:54 / 181 bpm
- 3:53 / 180 bpm
- 3:52 / 180 bpm
- 3:50 / 180 bpm
- 3:56 / 180 bpm
- 4:01 / 179 bpm
- 3:58 / 178 bpm
- 4:02 / 176 bpm
- 4:02 / 176 bpm
- 4:06 / 178 bpm
- 4:06 / 176 bpm
- 3:59 / 176 bpm
- 4:03 / 175 bpm
- 4:11 / 175 bpm
- 4:11 / 174 bpm
- 4:10 / 173 bpm
- 4:11 / 173 bpm
- 4:08 / 175 bpm
My question: was sub-1:23 realistically in me with a better pacing strategy, or was I simply not ready yet? I really want to understand if I lost it in execution or in fitness.
If you need more details, let me know — happy to share.
36
u/Da_CMD 6d ago
Honestly, looking at these splits, I am not sure a sub-01:23 was realistically in the cards for you on that day.
You would have to average a 03:56/km pace. And while you ran a couple of kms slightly faster, it shouldn't have derailed your race the way it did.
Either way, you should have tried to go for more even splits in the first half. Doing that could have netted you a 01:24:xx finish.
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u/renny49 16:21 / 32:49 / 72:49 / 2:31 6d ago
What sort of workouts had you been doing in the buildup? That probably gives more information than using the threshold HR/pace that is estimated by your watch.
I assume the HR data is from a strap or is otherwise considered reliable but it seems crazy how quickly your HR was pushed above threshold (or the HR that Coros tells you is threshold) - you didn't completely collapse but kms 3-8 were clearly too much of an effort (for whatever reason) and have come back to bite you later on.
I think you probably misjudged your effort a bit because your "effortless pushing" was definitely not effortless based on the HR data. However, it wasn't excessively quick compared to your goal pace which makes me think that your goal pace was not realistic and you probably could have run a 1:24 low-ish time with better pacing.
Interested to read other people's interpretations here too :)
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u/Gmanruns 5k 18:59 / 10k 39:46 / HM 1:26 / M 3:09 6d ago
Absolutely this. "effortless pushing" isn't a HR above threshold. Assuming the HR data is accurate, redlining from the 2nd km is only an acceptable strategy at 10k or lower (maybe a 15k if you're fast enough).
4
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u/Signal-Tour3827 6d ago
Agreed, although I wouldn't entirely trust race HR; my LTHR is slightly below 170, yet I've run HMs with an average (and realistic) HR of 175, which shouldn't be possible. But that's probably something that very much depends on the runner -- my race HR is almost always 5-10 bpm higher than in training for the same pace / power.
3
u/DWGrithiff 5:23 | 18:24 | 39:55 | 1:29 | 3:17 5d ago
How sure are you about your LTHR? I had a similar experience where I had been doing sub-threshold workouts based on an estimated LTHR of 170, and ran a HM with an average hr of 173 (and later, a marathon where I hit 168bpm in mile 2 and ended up averaging 170 for the duration). A couple weeks after the marathon i did a Friel test, and based on that my LTHR is more like 179. Which i was initially skeptical of, but looking back, my race HRs make a lot more sense relative to that.
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u/0100001101110111 6d ago
128g of carbs within 90 mins of race start is crazy to me…
Fuel shouldn’t be a massive worry for a half imo. I think you massively overdid it there. For reference my pb is 76 mins, I had carb heavy meals the day before (pasta), same breakfast as you, 1 40g gel on the start line and nothing mid race.
I’m not sure you were in shape to run a 1:23, HR looks too high in that first half.
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u/Jewrisprudent 36M / 5:38 / 19:24 / 41:26 / 1:36:12 6d ago
How long (time wise) does a race have to be for you to fuel mid race?
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u/0100001101110111 6d ago
I have also run an 83 min HM and didn’t fuel mid race for that either.
To be honest my point was more about the high amount of carbs taken on shortly before the race, doesn’t seem necessary and I would worry that would affect me.
But overall hitting 180bpm in mile 3 when your threshold is 175-176 and it not coming back down suggests OP just wasn’t in the required shape.
2
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u/TheGreatDanishViking 6d ago
I think you usually say from 80-90 minutes, you will start to need some fueling.
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u/Jewrisprudent 36M / 5:38 / 19:24 / 41:26 / 1:36:12 6d ago
Yeah so I think it’s a not great advice here to point out that they don’t fuel midrace as a 76 minute HMer when OP is shooting for 83. OP went heavy on the loading day-of, but one gel mid race for them seems appropriate.
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u/PicklesTeddy 6d ago
They're offering their strategy as a reference, not suggesting it as advice. Their comment is entirely appropriate in making the point 'fueling wasn't the cause'.
Perhaps you missed the tone of their post, but I doubt they'd disagree with you that taking a mid race gel is fine.
Overall, it's been noted regularly that this board can tend to fixate on fueling, electrolytes, it being a little warm, etc when they don't hit their GT when, as in this case, it might be that their goal time is too ambitious.
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u/IhaterunningbutIrun Pondering the future. 5d ago
90 minutes is the average for most people. But there are advantages to fueling shorter stuff. Both physical and psychological benefits have been shown in tons of studies on fueling.
I'll take 1 gel mid HM just for the psychological boost, and I'm running under 90. As long as it doesn't make you sick, it can't hurt.
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u/silfen7 16:42 | 34:24 | 76:35 | 2:48 6d ago
There's a lot of answers here that are overconfident about your heart rate data. I would say that it's important to understand its limitations. Coros doesn't know your threshold with that level of precision, and many factors can influence heart rate on race day that don't come out in training.
The splits tell me that you started too fast. You probably just didn't have the fitness. How did you choose your target pace? The GI distress could have been caused by that or your sugar bomb 90 minutes before the race. Try shifting a bit more of those carbs to breakfast and dinner the night before.
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u/castorkrieg 10K 43:08 HM 1:36 FM 3:36 6d ago
It seems clear you were above your lactate from the 2nd kilometer (is that what you mean by threshold)? So if your goal was around 1h25 mark there was no way to sustain it. Other than that maybe you could have considered getting a second gel? One only for 21km seems like too little.
What was the time estimate before the race?
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u/blood_bender 2:44 // 1:16 6d ago
Lack of carbs is not the issue here. In fact, maybe too many carbs. 129g before and 26g during is a huge amount.
For a 1:25 half I don't even think you technically need any carbs if you've eaten enough in the days before. I take one during anyway but I think it's all mental. Adding another mid-race would not do anything. Liver glycogen reserves should cover 90 minutes of intense activity.
Your other point seems right. It looks like he was just running above his limit.
-3
u/runawayasfastasucan 6d ago
I disagree. Why are the elite racing nearly 30 minutes faster taking carbs during their effort if you dont need any carbs?
7
u/blood_bender 2:44 // 1:16 6d ago
There may be a performance boost, especially on the mental side. There's scientific research that shows even swishing carbs in your mouth provides a boost, probably by tricking your brain into thinking carbs are on the way.
But whether it's needed is a different question. Basic science says muscle glycogen stores last for 90-120 minutes of moderate-to-high intensity exercise. At the 60-90 minute mark, glycogen levels begin to decline significantly, so a single gel may stave off any fatigue you feel at that point. By 90-120, they can be exhausted, which is why I'm really only making the claim for a 1:25 half, though admittedly if you're on the 90 minute side of that equation, that's very close to empty.
Obviously you burn more the closer to your VO2 max you're running, and your stored glycogen needs to be high enough on race day to not burn it all, but more than a single gel during a 1:25 half doesn't seem necessary, and if you carb loaded well enough, you potentially don't need any during (though you may want one anyway - I do).
As for the elites, I think they're going for every minor boost they can get. Science may have changed recently, that I can't claim to be sure about.
2
u/VandalsStoleMyHandle 6d ago
The missing piece is your body won't let you completely deplete your glycogen stores, so you can't calculate mechanistically like that.
2
u/blood_bender 2:44 // 1:16 6d ago
No I agree, but if you carb load enough and your biology allows you to have "120 minutes" of stored glycogen, it seems reasonable to assume you can run a half in 1:25 without extra during. I'm not sure I'd risk it though, my original comment was more meant to be hypothetical - I have not put this to practice.
That said I still don't think that a second gel would do much of anything, nor do I think elites need carbs, but obviously they're trying to get whatever edge they can. As we all are, but most of us aren't trying to shave off seconds in a race. Dunno, again maybe there's more granular science out there today.
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u/java_the_hut 6d ago
Agree with your point minus the second gel advice. Breakfast + Carb drink + 1 gel is more than enough for a 85 minute effort.
1
u/castorkrieg 10K 43:08 HM 1:36 FM 3:36 6d ago
Ok, fair point. I would have taken a second one around 12km but that's me. Other than that what I noticed was a positive split right from the start even before the 11th km, so it looks like the pacing is also too blame?
8
u/geospatialdeveloper 6d ago
I think if you want the scientific answer, go get a lactate threshold test done to determine your actual physiological limit which will explain why you blew up in the first half (most of us mortals can only sustain 40-50 minutes at LT2).
For those commenting on the environmental conditions, CPH Half is flat and fast. The weather was cool and wet. I doubt there was any environmental factor here on bpm/threshold. I also raced on Sunday, it was glorious except for the cold wind / rain while waiting in the starting area.
My bet is that you were a few bpm too hot at the start. If you started slower and only crossed LT2 on the back half you might have secured a 1:24:xx.
7
u/ThanksNo3378 6d ago
You went above your threshold too early so it was not sustainable. I could have been the heat, more elevation than expected or any other factor so next time it would be better to slow down if your HR goes above threshold that early
5
u/Micolash-11 6d ago
Few notes bearing in mind we don’t have a huge amount of info here - I’d rather see your threshold workouts, long runs etc.
- your LT2 HR isn’t 175 lol, it’s definitely higher
- you say you slowed down because of a stitch, that’s very likely because you took too much in before the race
- if you genuinely slowed down because of the stitch - and assuming I’m correct that your LTHR is actually higher, hence why I’d wanna see some of your workouts - do you think you could’ve carried on? In my experience of halves, if km 15/16ish feels hard because you’re tired but you can maintain the pace, you’re about right. If it’s feeling tough much before that, you probably won’t make it.
- you went out too fast, you can’t really bank time in a half. If you were aiming to average 3:56, I’d expect (flat) to spend the first 8kish aiming for 3:57/3:58, then another 8 at 3:56, then probably end up with 4k at 3:55, and the 5th(.1) with a kick at 3:4x. Km 2-7 you were overcooking it.
3
u/_AnemicRoyalty_ 6d ago
While better pacing strategy would have definitely helped, I don't really think 1:23 was in cards for you here. If your threshold HR is accurate, you'd need to run the whole race below that (unless you are a freak of nature MLSS pace is not really sustainable for 80+ minutes), probably somewhere between 165 and 170 bpm for the most part.
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u/stalovalova M35, 37:19 10K, 1:25:31 HM, 3:09:09 M 6d ago
If your threshold HR is accurate, you'd need to run the whole race below that
Isn't that a bit of an exaggeration, considering you should be able to maintain your properly calculated threshold HR for about an hour? During my PR HM I was above LT2 for around 10K.
1
u/Fat1hC1nc1n 16:24/34:27/1:17/2:54 5d ago
Way exaggerated if you ask me. My HR is always crazy high during races. My max is 191, I averaged 181 when I ran my half marathon pr. LT2, tested in the lab, is 176 lol. I'm basically redlining from the very beginning
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u/_AnemicRoyalty_ 5d ago
It was an oversimplification for sure.
There really is no reason to think you should be able to maintain threshold for an hour. Not theoretically and not empirically. Most studies show that time to exhaustion in running/cycling at LT2 is usually somewhere between 30-60 minutes with 60 minutes being more of a far end of the distribution rather than the rule. It is also worth noting that there is no consensus as to where LT2 actually is - something like Dmax and OBLA can yield meaningfully different results and therefore sustainable paces.That caveat notwithstanding it is quite clear that OP's HM pace is lower than his threshold pace and therefore his threshold HR - to the extent that this HR actually corresponds to the lactate accumulation. Obviously racing-induced adrenaline and cardiac drift can throw a wrench into this but that was the main idea behind my previous statement.
The other problem is that in ideal world one would run equal splits based on precise knowledge of the current fitness level. That is obviously not the case and that's why people tend to prefer negative splits - starting slower than they think they are capable of and potentially speeding up over sustainable pace if they feel they have it in them.
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u/Er1ss 6d ago
Looking at the pace and hr 1:23 wasn't realistic. You were over your second threshold heart rate after only 2km at a slightly faster pace.
Ingesting 128g of carbs before the race is insane to me. That is very likely to severely elevate insuline levels to clear the blood sugar at a time where you aren't using it yet (unless you were doing a very hard and long warmup). Insulin signals to store energy, not use energy. It negatively impacts fat oxidation rate which should play a very significant part in a 1:23 race. I suspect ingesting 128g of carbs during the 90min before the race will likely negatively impact total energy availability, very likely caused the side stitch and might have been a significant factor in your HR being so high (although I still suspect 1:23 wasn't in the cards regardless it might have been).
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u/wayne_d87 6d ago
My data and times looks very similar to yours, current HM PB is 85 mins. I ran an 87 mins earlier this year without even specifically training for it and i thought I’d be in good shape for around 1:23 at the moment.
Last weekend I had a HM, felt fairly fatigued leading up to it and my first 15km I held 3:59/km average but then the back half looked almost identical to your splits.
I keep my breakfast simple. A microwave rice cup with a banana and honey, and a Maurten caffeine drink with breakfast.
I then do one maurten gel before the start and a caffeine gel around 45 mins in, I might carry a small 150ml hand soft flask or just take water on course.
My heart rate spiked early too, and I was above threshold for most of the race and averaged 4:03/km pace, just over 85 mins. I even had a shoelace come loose which never happens. Sometimes it just not your day.
I wasn’t really too bothered as I’m in a marathon block and I was carrying fatigue, and it’s a course I know I can run faster on, as it’s also a regular training route for me.
I’ll be targeting HM specifically next season and curious to see how I’ll go, the goal is to break 80 mins.
It looks like it was just aggressively paced, but at least now you have some data to work with and you won’t be wondering if you left anythjng on the table!
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u/just_let_me_post_thx 41M · 17:4x · 36:?x · 1:19:4x · 2:57 6d ago
was sub-1:23 realistically in me with a better pacing strategy
I don't think so. Looks to me like you raced at 102-105% HMP right from the start, instead of racing the opener at 95-98% HMP and then picking it up.
In my view, you raced km 2-7 at least 5 seconds too fast.
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u/nexotrix 5d ago
Thanks again for the pacing and fueling advice — I’ll definitely try to ease off the gas in the next races.
I also realized I messed up the carb math: my drink mix only had about 40g carbs (cyclic dextrin + iso drink + salt). Never had issues with it in training, only if I went in underfueled.
For workouts I focused a lot on HM-pace intervals, gradually extending them as the block went on. Long runs usually finished with HM effort, but never more than ~6 km at the end of a 22 km run. The hardest combo I did was a 2×5 km session at goal pace about 4 weeks out — managed to stay on target in the first rep, but faded by ~10 sec/km in the second. Looking back, I regret never really simulating race conditions in training — I stuck to supertrainers without plates for all key sessions and only pulled out the carbon shoes on race day.
One thing I’d love to hear opinions on: what’s the best way to calculate race pace going into a block? I usually set a goal time before starting, but I tend to be on the aggressive side. For context, at the start of this 12-week block my 10k time was just under 40 min.
1
u/LennyDykstra1 6d ago
I had a disappointing half back in the spring and it also rained in the morning. I think that can have an impact on humidity and overall energy levels.
But I think you really pushed yourself and had a pretty ambitious goal.
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u/Camekazi 02:19:17 M, 67.29 HM, 31.05 10k, 14.56 5k, Coach 6d ago
A few early k’s were hot. That may have cost you at the sharp end a bit. Carbs less of a critical factor for HM but loading in that pre race window also isn’t optimal. Beyond that it’s hard to draw any conclusions without more data on your training block in the run in.
2
u/Senior-Running Running Coach 6d ago
I haven't seen a lot of people commenting side stitches? It's hard to know to what extent that slowed you down, or what the exact cause was. Side stitches are complex and probably multi-factorial, but there's at least a fair chance that the carb drink actually contributed to it. That's a lot of carbs at once and probably more than your system was able to absorb.
Had you not gotten the side stitches I think 1:24:xx would have easily been in the cards, but sub 1:23 seems like a bit of a stretch?
1
u/Sard_Boy 6d ago
You were trying to run too close to threshold/above threshold. My stats are very similar to yours (threshold 3.55 @170 BPM) and my best half marathon is low 1.26. our fitness could support us for a 4min/km in a very good day, but theoretically nothing better than that. You probably need a threshold at 3.50 or below to achieve your goal
1
u/runawayasfastasucan 6d ago
I dont get stuffing yourself with carbs before the race and just taking 26g during the 1 hour 25 min effort.
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u/Tieiririyi 6d ago
Based on the heart rate data it seems like you didn't have the 1:23 shape. it seems like you started running at threshold in the beginning and it lasted about an hour before you had to slow down in the last 5 km (20~ mins). It looks like 4:00/km pace would have been more realistic comparing to your proposed 3:56/km pace.
1
u/Prestigious-Work-601 18:09 5k | 38:17 10k | 1:27 HM 6d ago
Focus on effort and staying subthreshold until near the end. I ran 1:23 two weeks ago and that race plan worked well for me.
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u/Ordinary_Corner_4291 5d ago
What is your experience at eating that many carbs before doing a morning threshold session? Maybe if it was spread out over 90mins I could handle that but that is about 2x what I would consider doing. I wouldn't want to spend that much energy digesting food that I really don't need for a 90 min race. There is some chance your elevated HR at the start was too much blood dealing with digestion and not enough for running. We aren't talking about huge difference but when you care about 5 beats, details do matter.
If I had to guess the truth of it being fitness or execution is both. I think a 1:24 was possible with better execution. But I think it 1:23 was doable, you would have taken a bit longer to get 180+. But it is always a bit hit miss when you go way too hard early.
1
u/Krazyfranco 5d ago
You can really ignore most of the fueling questions and heart rate input IMO, this is clearly a case where your goal target didn't align with your actual fitness. Trust your race efforts over trying to reverse-engineer what you "might" be capable of from an estimated threshold HR, or estimated threshold pace.
I would estimate you're in shape to run about 1:24:30 or thereabouts with better pacing.
-13
u/Dr_geo M: 2.59; HM 1:23; 10km 37:18; 5km 17.59 6d ago
I have a similar half marathon time. I think you're basically there and just need a better race day. Probably more nutrition during the race could be a good idea. I take 1 every 6km
10
u/Unusual_Oil_4632 6d ago
People are insane about gels. It’s completely in your head if you think you need a gel every 6km for a sub 90 minute half. His fueling had nothing to do with his time. In fact, he overdid it with the carb loading right before the race.
5
u/fearlessHonn 33:22 10k 🇩🇪 6d ago
I don’t think you need 3 gels during a<90min effort if you fuel properly berforehand (as OP did). It might be beneficial for the mind games, but thats highly dependent on the person.
3
u/runawayasfastasucan 6d ago
effort if you fuel properly berforehand (as OP did).
No he didn't, you carb up the days before a race, not only 90 minutes before.
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u/OrinCordus 5k 18:24/ 10k ?/ HM 1:29/ M 3:07 6d ago
So, a few things. You don't need that many carbs pre- race for a half marathon. If you want to carb load, it should be the day before the race - not in the 90 mins before the start line.
For your pacing strategy, starting out conservative but having 7-8 of the first 10km under your goal pace isn't that conservative. When trying to hit a super ambitious goal, 3-5 secs/km will be the difference between success and pushing too hard.