Long run in summer: hours, water and pace so you don’t really sink

The long run in summer is not solved with courage or stubbornness, but with fine adjustments: heading out at a sensible hour, drinking before you’re thirsty, easing off a gear and accepting that the thermometer trains too. For those preparing for an autumn marathon, those 24, 28 or more kilometer sessions in July and August are an uncomfortable but decisive testing ground. That’s where real endurance is measured, the ability to eat and drink while running and, above all, prudence.

Heat changes the rules. Your heart rate rises sooner, pace becomes deceptive and perceived effort increases even though your legs may want to go slower. That doesn’t mean the session loses value: it means the goal is no longer to run fast, but to sustain aerobic work without entering a spiral of fatigue, dehydration or overexertion that later forces you to pay for it for several days.

Heat does not forgive, but it can be read

Training long in high temperatures requires understanding that the body prioritizes cooling itself before performing. In an environment close to 30 degrees, heart rate can rise easily even at modest paces, and the feeling of breathlessness appears sooner than one would expect in spring. It’s not a sudden bad form; it’s basic physiology, the price of thermoregulating while running.

That’s why, in summer, a long run shouldn’t be judged by the GPS watch as if it were absolute truth. A kilometer at 5:10 in January may feel controlled, while that same pace in August, with humidity and sun, becomes an effort close to the limit. The useful reference is breathing, the ability to talk and a stable heart rate, not the number glowing on the screen.

It’s also worth assuming that heat wears you down cumulatively. The first ten minutes seem manageable, the next twenty even more so, and then suddenly the body enters a kind of fog where every stride costs a little more. That change doesn’t always announce itself dramatically; sometimes it arrives like an invisible slope that turns a normal session into a small crossing through soft sand.

The time of day matters more than it seems

The most reasonable window for a summer long run is usually the first hour of the morning or, secondarily, sunset. Heading out when the sun is already beating down turns a resistance session into a constant negotiation with the environment. Getting up early isn’t an obsession of obsessive runners; it’s a simple way to reduce temperature, radiation and mental wear.

The route matters too. In summer, a course with shade, fountains or looped sections near home is worth more than an endless straight line with no way out. The plan gains value when it reduces friction: fewer crossings, less exposed asphalt, fewer dead spots where there’s no choice but to keep going by inertia even though the body is asking for something else.

In marathon training, Sunday at noon is usually not the best picture for the long workout. The difference between heading out at eight and heading out at eleven can be the difference between completing the session with confidence or finishing by dragging your feet. Sometimes the decisive detail isn’t in the shoes or the brand of gel, but in that two-hour margin that completely changes the experience.

Hydration: water alone falls short when the run gets longer

Drinking well in summer starts before you run. Arriving at the starting line already somewhat dry is a habit that’s much more harmful than it seems. A 400 to 600 milliliter intake of fluid in the hour before, preferably if it has been tested before and causes no discomfort, is usually a useful reference for reaching the effort with the body less exposed to initial fluid loss.

During the session, water helps, but it doesn’t always suffice. In efforts that last more than an hour and a half, sweat carries away sodium and other minerals that are also lost along the way. Isotonic drinks, gels with electrolytes or a combined strategy help sustain performance and reduce the risk of cramps, energy dips and that slump that comes when the tank stops responding.

The practical idea is simple: regular sips, not heroic gulps. Hydration works better as a steady drip than as an emergency fix. In long, hot runs, taking between 700 and 900 milliliters per hour may be reasonable in some cases, although each runner loses a different amount depending on sweat rate, humidity and pace. Weighing yourself before and after a session, with the same gear, gives a more reliable clue than intuition.

What happens afterward also matters. Replenishing fluids isn’t just about refilling a bottle. Recovery speeds up with water, salts and real food: fruit, gazpacho, yogurt, bread with something salty or a full meal that restores energy and helps bring balance back. Running long in the heat leaves a wear and tear that isn’t always noticeable in the moment, but it is two hours later, when fatigue starts charging interest.

Sustainable pace: summer is not for proving anything

The summer long run is run slower than the ego would prefer. That is perhaps the most useful lesson. The goal is not to compete with the workout, but to accumulate quality aerobic minutes and finish with the feeling that you could have done a little more, not that you emptied the body halfway through.

A simple reference is the conversation test: being able to speak in full sentences without gasping. If every answer breaks in two, the pace is too high. If, on the other hand, the stride becomes excessively lazy, part of the stimulus may be getting lost. The sweet spot is usually in a comfortable, steady and honest effort, the kind that lets you sustain the session without the heat turning it into a survival fight.

In the middle of marathon preparation, many people fall into the temptation of running the long run too close to goal pace. In summer, that multiplies the risk of paying for it later. Endurance is built better with patience than with bravado. What matters is not who pushes hardest at kilometer seven, but who is still intact at twenty and twenty-five.

Eating before and during: the mistake doesn’t always show at the start

Heading out without a tested breakfast is a poorly calculated bet. If the run is in the morning, it’s worth choosing foods that have already worked in other sessions: toast with honey, oats, banana, coffee if it sits well. The key isn’t to improvise a perfect diet, but to avoid digestive surprises while the heat is already doing enough work on its own.

During the run, the practical threshold usually changes after 75 or 90 minutes. That’s when gels, carbohydrate drinks or even easy-to-digest fruit start to become useful, always tested beforehand in previous training sessions. The body doesn’t appreciate originality halfway through an effort; it appreciates repeating something familiar, especially when the temperature is putting pressure on from every side.

A simple rule for long efforts is to aim for around 30 or 60 grams of carbohydrates per hour, depending on duration and intensity. There’s no need to turn every outing into a laboratory, but it is important to understand that fuel is trained too. Summer is precisely the time to check what the stomach tolerates when sweat is pouring and the clock gives no breaks.

Acclimatization: heat is learned, not beaten overnight

The body adapts to heat, but not in a couple of magical days. Acclimatization usually takes between one and two weeks of gradual exposure, with improvements in sweating, plasma volume management and the ability to keep temperature under control. Put simply: the body starts cooling itself better and losing less efficiency.

That process can’t be forced. The best strategy is to gradually increase exposure and avoid sudden jumps in volume or intensity on the hardest days. Solid adaptation is worth more than an isolated act of heroism. Anyone who tries to get through summer as if it were a test of endurance usually ends up paying too high a price for the rest of the week.

The personal context matters too. It’s not the same to run with a solid base of mileage as it is to do it after irregular weeks. Nor is a humid morning by the coast the same as a dry day with wind and overheated asphalt. Heat is not one single thing; it changes its mood depending on the time, humidity and terrain.

Summer as a laboratory for autumn

Summer long runs aren’t just for building endurance. They’re for rehearsing everything that will be taken for granted in autumn: which breakfast sits well, which gel feels better, when fatigue appears and how much water is needed to avoid arriving empty at the end. It’s a dress rehearsal with a focus on the details, and in marathon running, details weigh like bricks.

It’s also the time to test gear. A light visor, a technical shirt that doesn’t soak up like a sponge, a sock that doesn’t rub when sweat builds up… all of that may seem minor until the heat turns it into a serious discomfort. Summer unmasks what goes unnoticed on milder days.

Even the mind is trained here. Running in the heat forces you to live with discomfort without dramatizing it, to distinguish normal fatigue from a real warning, to accept that the session may not look good on Strava but will on the training plan calendar. That mental learning is less flashy than interval training, but often more useful in the final stretch of a marathon.

What signs indicate it’s time to slow down

Not every discomfort is a good sign. There is a clear line between the logical effort of a long run and the symptoms that require you to slow down or stop. Dizziness, chills, confusion, a growing headache, persistent nausea or a racing heart that doesn’t match the pace are signs that shouldn’t be normalized. Heat is not something to negotiate blindly.

Premature fatigue also deserves attention. If the body stops responding at minute forty with unusual heaviness, the solution is rarely to insist. Reducing distance, walking for a few minutes or ending the session early is not a failure; it’s judgment. In summer, respecting that limit can save the entire training week.

The same principle applies to poorly slept mornings, heavy workdays or weeks when hard workouts pile up. Endurance doesn’t improve through indiscriminate accumulation, but through assimilation. Consistency works better than obsession, especially when the environment is already bringing enough stress of its own.

The long run changes depending on where you are in the build-up

In the base phase, the long session is usually simpler, more continuous and less ambitious. The goal is to sustain running time and strengthen aerobic endurance without adding too much extra load. As the race approaches, however, gentle progressions, controlled-pace blocks or slightly quicker finishes may appear, always with common sense.

That contrast matters because not every long run is chasing the same thing. A steady outing helps build foundations; a progressive one teaches you how to finish under fatigue; one with specific segments brings you closer to the real effort of marathon day. Choosing the right stimulus avoids repeating the same workout out of habit, which is a polished way of stagnating.

The key is not to turn summer into a season of constant demand. Not every long run has to end hard, and not every week needs more pressure. The body needs building weeks and recovery weeks to assimilate. Without that alternation, the line between preparation and overload disappears quickly.

A well-done endurance run is recognized by how it ends, not how it starts

The good summer long run usually starts with caution, passes through a zone of tolerable discomfort and ends without collapse. That steady finish says much more than a too-fast start with an air of self-satisfaction. In marathon running, as in preparation, the merit lies in managing, not showing off.

Heat, in reality, places a kind of mirror in front of the runner. It shows who drinks too late, who goes out too fast, who ignores rest and who knows how to adjust. It also rewards those who understand that endurance is not a race against the clock, but a patient construction of tolerance, fuel and head. Anyone who learns to run long in summer usually arrives in autumn with more resources than they imagine.

And that’s where the value of these sessions lies: it’s not about surviving summer out of sheer stubbornness, but about turning it into a school of precision. The runner who heads out in the heat, yes, but heads out prepared, comes back with more than kilometers. They come back with judgment, with an understanding of the body and with a base that can’t be improvised once marathon season is already in the air.

Este artículo contiene enlaces de afiliado: si compras a través de ellos, se genera una pequeña comisión sin coste adicional para ti. Más información.