Rotterdam Marathon 2025

Crossing the Erasmus Bridge

Let's start at the end. I pulled the plug at the 35km mark of the Rotterdam Marathon 2025. My first marathon DNF.

Don't worry, I'm not going to write a list of excuses but I would like to share my thoughts on what led to this outcome.

To put some context on this it's important to understand what my level of preparation was like. You can see below I was relatively consistent with volume over the three months leading up to the race and my November and December were decent too. However, this overview doesn't tell the whole story.

Monthly volume

Let's jump across to Strava to see a weekly breakdown. (The race was April 13th.)

Weekly volume

I'm comfortable running 80km per week. 90km would be a bigger week and 100km is about as much as I can fit in logistically and it's close to my current limit physically. Clearly, there's a dip in volume over a two week period and a couple of weeks building it back up at an important part of the build. This influenced the quality of my preparation but I don't think it entirely explains what happened on the day.

In late January I developed a small bit of soreness in a glute tendon. It's something I've had before and I was confident managing it. About a week of modifying my programme and it was basically gone, it did mean skipping a 10 mile race I had planned. I was back into my regular training nicely and had my sights set on a half marathon on March 2nd.

The next curveball was some soreness in a hamstring during a stride. I have strides in my training a couple of times a week and usually love them. Ironically, I think they are a useful part of reducing injuries occurring. The half marathon I had coming up was an out an back route with the second half being largely downhill. This is extremely challenging for quadriceps muscles and prolonged, fast, downhill running is not something I'd have in my training often. I decided to use 15 second downhill strides to expose myself to this on a smaller scale. There's also good evidence that exposure to downhill running can reduce eccentric muscle damage for up to three weeks. (This is called the repeated bout effect.)

My mistake was probably getting too excited at the prospect of running fast and it not feeling very hard as it was downhill. Like an overexcited child basically! I was alternating reps up and down a slope and on my first downhill I felt some soreness. No sniper shot but enough to know I needed to stop. Again, I wasn't overly worried as I knew I could train around this but I was definitely pissed off.

Within a week I was able to complete strides again (on the flat) and did a session around threshold pace which would have been similar to the half marathon goal pace. I was ready to go.

Until I wasn't....

Picking up a cold, race out the window

This was where I was starting to question things. My first bout of illness in a few years came at a shocking time. It was a bog standard "common cold" but I seriously underestimated it. I knew I needed to back off and had no problem resting up when I clearly had symptoms. I ran easily the first day I noticed feeling slightly off, this was a Friday and the half marathon was the Sunday. I woke up on Saturday and clearly had some sort of cold. Irrationally, I was still holding out hope for a miraculous recovery. I went through the motions early on Sunday morning as if I was going to the race but while eating breakfast I had to question what I was doing. The race was ditched and I went back to bed.

I did feel better quite quickly and eased myself back into running. The running felt fine, heart rate was back to normal and breathing was okay. What I wasn't expecting was the level of muscle soreness after standard runs. My only explanation is that under the surface I was still fighting off whatever viral infection I had, the systemic inflammation involved here and adding new muscle damage was not a good combination.

Like most people, I don't have a blank canvas to plan my running. I squeezed in a 32k long run on a Friday evening five days after skipping the half marathon. This was due to a stag on the Saturday and knowing I wouldn't be running on the Saturday or Sunday. The run went quite well and I finished with 10k at marathon effort.

30k progression run

It wasn't until the following week that I realised I probably pushed too early here. I had quad DOMS beyond what I would have expected. I was clearly starting to worry I hadn't enough quality work done as I included a threshold session on the Tuesday and a key marathon session on the Saturday. The muscle soreness during the long run was not in keeping with what I'd expect, the walk to the car afterwards was horrendous. Despite that, the performance in the session was quite good. It was a 35k run with a 6, 8 and 12k block at marathon effort. I was around the 3.53 min / km pace for these blocks with a HR that should be sustainable for a marathon. It's worth noting that it was 3-6 degrees for this run.

Key session - 6, 8 and 12k at marathon effort

I recovered from that with some cross training and managed to train quite well for the rest of March. I knew during the build there were more interruptions than I would have liked but I believed there was still enough quality in there.

On recapping, I had five long runs with a significant chunk of marathon effort work. I went over 30km six times and I was in the 3.53 - 3.55 ballpark for marathon pace work I felt.

My taper was uneventful and I was able to include good quality work, albeit in low volumes. Traveling to Rotterdam I was optimistic about my chances of being close to 2.45. I was well aware this would be a "best case scenario" result.

The travel and lead in to the race was smooth sailing. My wife and I stayed in an AirBnb in the western suburbs and my parents landed in Rotterdam the day before the race. We met them for lunch that day and I was really hoping the glorious weather we had was going to disappear by the next morning. It hit 19 degrees that day and I knew my gameplan for the next day would have to change. The forecast was for the temperature to dip and it was looking like it would get up to 15 degrees with cooler temperatures at the start of the race which was 10am.

I knew starting off at 2.45 pace wasn't a good idea so I settled on seeing how I felt at around the 4min/km pace. In truth, I could see early on that I was working way too hard for this pace according to my heart rate. In training, this would be mid to high 150's. The splits below show that pretty early I was over this. As is always the case with a marathon, it's difficult to differentiate between how you feel and what the objective feedback is telling you. I didn't feel like I was pushing too hard and my gut feeling was "what is going on, how is that so high".

I appreciate you can't solely use heart rate to gauge effort level but when it's so close to what I know is around my threshold you have to pay attention.

5k splits

From training runs at marathon effort I was used to seeing my heart rate at about the 165 mark. To bring things back to this level would have required slowing significantly. 4.15-4.20 min / km pace I'd estimate. I was weighing this up at about the 15k mark, the alternative was to keep going and see how it panned out. Clearly, I took the latter option.

10k in

I met my wife and parents at the 23k mark for a bottle handover and they commented afterwards I was moving well and looked pretty fresh, I did feel quite good at that stage and was happy to keep things steady. I knew that at 30k we started heading out of the city to do a lap of a lake and that at 35k you were at the far side of the lake and starting to loop back into the city to finish. As you'd expect, maintaining your pace around the 30k mark becomes more challenging. I think what tipped me over the edge here was the clouds parting and being on an exposed part of the route. The heat felt intense, you know it's hot when you can feel it bouncing back up from the road. Looking back on the weather data it was about 17 degrees at that time fo the day with a wet bulb temperature of 12.3 degrees (thanks ChatGPT). That's certainly hot enough to impact my performance.

1k Splits

Essentially, you can see things getting harder from the 30 - 35km mark. I knew I was getting hot and the effort level I was at wasn't going to be sustainable. I slowed to 4.15's and then to 4.40's but I knew the game was up when I started getting goosebumps and shivers. That's a clear sign you're overheating. That was it, watch stopped and stepped off the course. I had about 30 seconds of slight dizziness but I was I was fine after that. Pissed off, but fine.

Within five minutes of walking along the course I was delighted with my decision to stop. I had a horrendous experience at the Cork City half marathon last year. I ignored similar feelings and "pushed on".....that led to a spin in an ambulance and a long stint in the medical tent. Repeating that would would have been inexcusable. I firmly believe the dangers of exertional heat illness are poorly understood by runners. I'd encourage you to listen here.

I've given the day plenty of thought and discussed it with friends who are experienced runners. Looking into the physiology of exertional heat illness has also been helpful, I had a good head start at this from last year! The summary is quite simple. I'm not heat adapted in any way, shape or form. This is likely due to doing all my training in the mornings when it's cool. Trying to run a marathon PB pushes you to your limit in perfect conditions, if the conditions aren't favourable the same effort is not sustainable. For example, the Paris marathon in 2023 when I ran 2.47 was an 8am start and the max temperature that day was 8 degrees. To get around the course without overheating in Rotterdam I'm estimating I would have needed to aim for a 3.05 - 3.10 finish time. In all honesty, I feel like that's something I could do in a training run so the thought of it being the culmination of a big build up is extremely underwhelming.

At this point I'm at peace with it all. Stopping showed I learned from previous experiences and that's half the battle with trying to improve running performances. There are some practical takeaways too.

As it's coming into summer I'm going to try and run in the middle of the day more. I don't see myself doing loads of other heat related training, I think more running in the sun could be all I need. The other positives I'm taking are that my fueling and hydration on the day went well, I didn't have GI distress despite the heat which is a positive when you're hitting 90g of carbs per hour. Coming through the race without injury has to be appreciated too.

I plan on easing back into training and working on shorter distances over the summer. All going well we will have a new addition to our family in October so I'll give marathons a miss for a while. Maybe Valencia 2026!

Thanks for reading and as always I'd love to hear from anyone who has questions or wants to provide any feedback or insights.

Patrick

Running Buddy