for those who love the outdoors

18 June, 2024


Dehydration is no running joke

The summer is coming…but why do so many runners still try to outrun their thirst?

Warm weather jpeg

After too many days of running on wet, soggy trails and being whipped by the wind, it is nice to finally feel the warmth of the sun. With the weather forecast predicting more sunny days ahead of us, many people will be planning to get outside and enjoy a workout or two. But although we are still in the last days of the Spring and the temperatures are mostly mild, now is the perfect time to start thinking about hydration. 

Ensuring that you are sufficiently hydrated while running will not only keep you cool and comfortable. It can make the difference between finishing a workout, crossing a finish line or crashing out in a big heap and a DNF.

You would think that hydration is something that most runners would be pretty aware of. However, despite the fact that probably everyone has at some point experienced being dehydrated, the potential dangers and long-term effects are routinely dismissed. In fact, many runners would rather get quite uncomfortable and put up with some of the early signs of dehydration if it means that they won’t have to carry a water bottle. 

After all, water bottles can be heavy, clunky and leak while the fluid swishes around loudly when you run. It is also annoying to have to keep swapping your carrying hands to avoid ending up with one massive muscley arm. Sure, you will probably get really thirsty and develop a nagging headache. But without a bottle to carry you can run with 2 free hands to wave around and high-5.

Chester Before

However, the longer you stay dehydrated, the worse you will feel and over time the symptoms of dehydration will start to bite. So if you are a free-handed runner you will feel increasingly tired and begin to lose your focus and concentration. This simple lack of fluids will then cause you heart rate to increase as your body tries to cope. 

As you become even more exhausted you will feel nauseous, dizzy and confused. If you carry on running and get more dehydrated you risk passing out or having a fit. Dehydration can escalate very quickly and unexpectedly like being on a runaway train heading for a crash. This puts you in real danger if you are out running on your own and means that it is just as important to be aware of the signs and symptoms of dehydration for yourself as it is to watch out for other runners. 

Of course, the more severe the symptoms of dehydration you suffer, the longer time off running you are going to need to fully recover. However, if you still think this is dehydration scaremongering and prefer to run with jazz hands rather than carry a drink then let me share with you a couple of cautionary tales.

Starting with last October’s Chester Marathon 2023, where after months of following my training plan to the letter I was primed to smash my PB. The start time of the race was 9am and the weather was forecast to be overcast with mild temperatures. But as I knew I tended to get dehydrated easily I did my research and had the route and water stations clearly imprinted on my brain. 

But I wasn’t overly concerned. Mainly because it was clearly advertised that the water stations would hand out water in bottles with ‘sports drinks’ spouts. Perfect, I thought. I can grab one from every water station and would get some marginal gains by running without the weight of my hydration vest.

Unfortunately the weather on the day unexpectedly grew to a very warm 23°C while any wisps of clouds left blocking the sun quickly dispersed. The water was also handed out in standard screw top bottles. As I hammered the course I struggled to drink as the water bottles mostly just spilled all over me. Which meant that by the time I was nearing towards 40km and still on course for a PB, I was extremely dehydrated and feeling terrible. 

I completely slowed down as I began to waver back and forth across the course while trying desperately to run in a straight line. I felt so sick, dizzy and delusional that I was extremely lucky to even finish. So rather than get a PB I ended up in the medical tent wearing an ice blanket for almost an hour while they tried to get my temperature down.

Chester After

Seemingly undaunted by my experience, 6 months later I ran the Boston Marathon in 2024. Every year the weather for this event is notoriously unpredictable and last April was no different. However, the weather boffins unanimously forecast it to be overcast and pleasant with a decent tailwind, making the conditions almost ideal. As the course is known for its unrelenting hills in the second half of the race and not being PB friendly, I went into it purely to enjoy the experience of running such an iconic race. 

Even so, I still had to run 42km and after Chester I knew I had to up my hydration game. Once again, I did my research and found out that water would be provided in paper cups from water stations approximately every 2km along the entire course. Since I could outdrink even the largest hydration vest I decided that I would instead run carrying a single bottle and simply refill it. This would allow me to have an almost unlimited amount of water that I could very easily drink whilst running.

The start time on the day of the Boston Marathon was 9am but it took several hours for 30,000 runners to be released in rolling waves. Unfortunately, by mid-morning the weather began to change. It grew from warm to hot, the tailwind disappeared and the humidity rose to create sauna-like conditions. By the time I started running it was a very late10.50am and the sun was truly out. 

Nevertheless, buoyed by adrenalin it went well for the first 18km and I easily drank from my handy bottle. However, despite refilling my bottle at every water station the midday sun started to cause me to overheat. With Chester in mind, I slowed the pace down and tried to drink even more. I also started to pour several cups of water over my head while refilling at each water station. Even so, as I ran alongside my husband, I began to resemble a red lobster. 

Fortunately in a moment of genius, he grabbed a bag of ice from one of medical stations dotted throughout the course. I managed to sandwich it under my hat and it was an absolute game changer. Before long I had somehow completely recovered and could pick up my pace again. It seemed incredible but for the rest of the race as long as I kept on top of the drinking, soaking and bags of ice I felt absolutely fine. Unfortunately, the same could not be said for my husband.

Ice bag 1

I have to say that my husband and running companion copes miles better running in the heat. He is also far more skilful at drinking from screw top water bottles and paper cups whilst running than I can ever hope to be. Which is why he coped perfectly fine, thank you very much, with the water bottle switch-up at the Chester Marathon. So why would Boston be any different? 

With so many water stations supporting the race he didn’t think that he would need to carry a bottle. And for the first half of the marathon he coped perfectly well up until just before we hit the hills at 26km. Just before that point I had noticed that he was very slightly fading and running slower so I tried to do the same. He then grew a bit quiet and didn’t seem that interested in drinking. 

He certainly didn’t share my unbridled joy while baptising myself at every water station. I kept trying to encourage him to drink more but he slowed and said he was starting to feel sick. As we approached the bottom of the first hill he slowed down even more and seemed to be in his own head.

Boston 30 Km

Suddenly he came to a stop and was promptly sick on the course. I have to say that he was not alone. Amongst the constant stream of runners the heat had already caused a countless number to be sick or collapse by the side of the road. But rather than stay put for any length of time my husband started walking again. He eventually managed a slow but determined jog and made it very clear that there was no way he was not going to finish. 

I was worried what it was going to take to do it but it became my job to help him try. As in Chester, it was a real struggle and he was up and down for the rest of the race while I tried to persuade him to drink more. But we finally made it over the finish line together and were both overwhelmed with relief. At last I allowed myself to relax but there was more to come.

Boston finish

As we walked through to the finish area to collect our medals and goodie bags, my husband had an overwhelming urge to sit down. However I was worried that his legs might cramp up and wanted to get him somewhere with a chair. Instead he immediately plonked himself down on the roadside curb almost in protest slump. 

There were signs hung everywhere directing runners to keep moving and not to stop. But he was completely exhausted and also a little bit cranky. I thought that if someone wants to try to move him along, please be my guest. Instead I tried to give him a little food and a drink containing some electrolytes but he point blank refused them both. 

Okaaay, I thought. Well, I was still thirsty so I quickly downed the drink and I tried to figure out what to do next. But then he started getting even crankier and slightly irrational having decided that now he absolutely wanted my drink and couldn’t understand why I didn’t have it anymore. Fine.

I got up to quickly find him another drink but as I did so I noticed that his voice was fading a bit. I turned and just managed to catch him as he fainted and slowly tipped over onto the pavement. Immediately, 5 medical staff came out from nowhere and started shouting and attending to him. He came to and started shouting right back at them as he cramped up in pain.

He was then transported to the medical tent where he spent quite some time being treated for severe dehydration. The tent was packed to the brim with a constant influx of other dehydrated runners. Luckily, he was not one of the even more serious cases that had to be carted off to hospital. In truth it was incredible that he was able to have finished at all because close to 1000 runners DNF’d that day.

Eventually my husband fully recovered as I had in Chester but getting so dehydrated undeniably put a dent in both events. And just because these bad experiences have taken place during marathons, you can still suffer the same when running shorter distances in the heat. With the seasons changing, hopefully my cautionary tales will persuade even the most determined free-handed runners to stop and think. Don’t underestimate the effects of dehydration because they can be very serious. At the very least, dehydration can affect your performance and cost you a DNF.

At least for me I have learned the hard way that the advantages of not carrying a water bottle will never be worth the risk of dehydration. Ultimately all you need is the heat, a lack of water and a lack of planning. Since you cannot always count on the weather you might as well get the last two right. As for myself, I am still not deterred but at least aiming to finish the next marathon while avoiding the medical tent. 

Let’s hope it will be this September at the Sydney Marathon 2024 where I plan to run firmly gripping my water bottle. Only time will tell whether I will also be sporting a bag of ice or two under my hat…

While I train in preparation for Sydney, I always find that after a long, sweaty run in the heat I like to eat something cooling that is salty and sweet has a kick to it. This hearty Melon salad with feta, chickpeas and pistachios hits the spot for me.

Melon salad with feta and pistachios CU2

Suzanne Anderegg


I am originally from Canada but I settled in the UK after studying at university. Sports have always been a part of my life and I have participated and competed in several throughout my childhood. But today I would describe myself as mostly a runner, a mother of 3 grown-ups and a keen cook. As a teenager I was a sprinter and a slightly reluctant cross-country runner but while my children grew up I started to run further and further distances. I never thought that I could ever run anything longer than a half marathon but when my runner husband decided to do a marathon for his 50th in 2019 I found that I had a serious case of FOMO. My children encouraged me to sign up for my first marathon and I ran it just to see if I could finish. Somehow my time was good enough to qualify for the Boston 2020 Marathon. However, due to Covid it was postponed several times.

Like many other runners, I spent much of my time in the Covid lockdown keeping up my fitness by participating in virtual races while waiting for the real events to start up again. As time went on I found myself becoming fully immersed in the world of endurance running and ran the Threshold Trail Series ultra, Race to the Stones. Unfortunately, by the time the Boston Marathon was finally held in late 2021, I could not go because US travel restrictions were still in place. Although I missed my chance to run it and will now have to requalify again at least my time spent keeping in good shape wasn’t wasted. These days I participate in everything from half marathons up to ultras and have also run the Great Glen Way and West Highland Way in the Scottish Highlands.

I also work as a Registered Nutritionist with children and families and founded the consultancy Just add water® in 2019. I write a blog at to give free information and advice about nutrition and running whilst also sharing some of my favourite healthy recipes. The website is mainly aimed at busy families who want to make easy to prepare meals that are both healthy and really tasty, and for active families who want to know what they should be eating before, during and after playing sport.

I have always enjoyed cooking and previously cooked as a profession and I like to share my passion for good food. I have been involved in teaching cookery in schools, children's centres and for the NHS. I also enjoy entering the odd competition to push myself out of my comfort zone. I was awarded Highly Commended at the Teflon™ Diamond Standard Awards 2020 national culinary competition in the category of Keen Home Cook and was a National Finalist in 2022 & 2019. I have also had my recipes published in The Guardian's supplement, Cook; and featured in the 2012 Waitrose LOVE life calendar (July); and selected for inclusion in the 2020 #AnyWhichWayaBix Weetabix recipe book.

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