As summer temperatures rise across the Northern Hemisphere, runners in warmer regions like South Florida already feel the heat. You donât have to wait for June 21st. In many places, summer conditions arrive much earlier. Now is the perfect time to revisit how heat and humidity affect running performance so you may adjust your training and remain strong, safe, and consistent in hot weather.
Running in the heat requires adjustments and patience (Image by ChatGPT)
In previous years, I have written about tips for summer running and guidelines to run in extreme heat. You can click the links in this paragraph to read those posts, which I highly recommend. This year, I am writing about a different aspect of this subject. While intuition tells us heat and humidity affect our running, this year, I want to dig a bit deeper into it.
I recently read about a study measuring the effects of those two elements on marathon performances. My goal today is not to show you how an 80Âș temperature or 70% humidity will adversely affect your marathon time. What I want to do is project what these difficult weather conditions affecting a marathon mean for you, training every day in the heat.
Letâs start with one of the studyâs most interesting takeaways: runners donât slow down simply because their core temperature gets too high. They slow down before that happens. In other words, heat doesnât just tax your body; it messes with your brain. The rate of perceived effort rises early, and that alone is enough to force a drop in pace. You feel like youâre overdoing it, even though your physiology is within range. This is not just psychological, itâs your body protecting itself. When the humidity is high, the fatigue effect compounds.
According to John Davisâ analysis of nearly 4,000 marathon performances across 754 races, the optimal temperature range for top performances is narrow: 35â55°F (2â13°C). Performance peaks around 48°F (9°C). As conditions warm beyond 65°F (18°C), things deteriorate, and they do so fast, especially when humidity becomes part of the equation. A heat index of 80°F (air temp and humidity combined) can slow your marathon pace by roughly 3%, and it only worsens.
In extreme cases, like 75°F and steamy, youâre looking at 6â8% slower marathon times. Thatâs 10â15+ minutes lost for someone aiming for 3:00, 14-19+ if you aim for 4:00, and 18-24 if you are shooting for 5:00.
But hereâs where it applies to your day-to-day running: that slowdown isnât just for race day. You need to adjust mentally and physically if youâre doing tempo runs, long runs, or any effort-based session in hot, humid conditions. Your body is under extra fatigue. Itâs not about being weak, itâs about heat load. Think of it as carrying an invisible weight that gets heavier the longer you carry it. You donât need a calculator to tell you this. If it feels harder, it is harder.
Humidity alone is not a significant issue until the temperature crosses 65°F (18°C). After that, humidity and heat multiply their effects. So, if youâre in a place like South Florida, where hot and humid is the baseline from May through September, your training isnât just slower, itâs under constant stress. Knowing and accepting it allows you to reframe your expectations, adjust your pace, and be kind to yourself when the stats on your watch donât match your effort.
Running in the heat
Davis recommends using the heat index rather than raw air temperature to judge effort. The âfeels likeâ measure is a more useful parameter. If youâre training in an 80°F heat index, expect that same 3% drop-off, even on a regular weekday run. The longer the effort, the more critical it becomes to respect this adjustment. And this doesnât just apply to marathoners. For any longer sustained effort, these principles apply.
Heat adaptation, hydration, and fitness all play a role in adjusting to the reality of the new weather. If youâve been out there, you know the stress is real, and if youâre not changing for it, youâre not training smart. Use this validated science to listen to what your bodyâs been trying to tell you. The heat isnât just uncomfortable; itâs performance-changing. If you ignore it, it can become dangerous and even life-threatening.
Share your experiences running in the heat in the box below, so other runners can benefit from them.
In the last post, we discussed the importance of building a strong aerobic base, one on which everything else can solidly rest. That post sparked valuable feedback. Many readers asked, “So, what comes after the boring stuff?”
Now that the foundation is in place, we build on it to get stronger and faster. Opposed to “the boring stuff” is what we Iâve heard called as “The Sexy Stuff”.
Speed over long periods/distances cannot stand alone. Adding speed work doesn’t mean abandoning the easy miles. It means balancing them with strategic sessions designed to improve strength, efficiency, pacing, and recovery.
Speed work isn’t a shortcut; it’s a complement. When done correctly and in harmony with your base mileage, it helps you become the strongest, smartest, and most resilient version of your running self.
Now that we have a base, it is time to work on speed (Image by CoPilot)
There are many types of speed workouts, each one with its own merits to help you run faster, with purpose, and without risking injury. The key is understanding that speed development isn’t about hammering every run to exhaustion. It’s about running with intention. Your easy runs remain the backbone of your training. But now, we are layering specific efforts designed for growth. To get faster, you need to run faster, but only when the time is right.
Examples of “sexy stuff” are the following:
1. Interval Training – Alternate fast running with recovery periods. They challenge your body to hold higher intensities and then bounce back. An example is short bursts of 200 or 400 meters at strong effort, followed by slow jogging. It’s tough but builds both strength and endurance quickly.
2. Fartlek – Fartlek means mixing in bursts of speed during a steady run. There’s no set structure. Just pick a landmark and push the pace, then ease up. It’s a fun, flexible way to teach your body how to change gears mid-run.
3. Tempo Runs – This is your chance to run at a challenging, steady pace that builds endurance and raises your limits. You should feel strong but unable to talk easily. These runs help you sustain faster efforts over longer distances without crashing.
4. Progressions – They are all about finishing fast. Start your run at a relaxed pace, then pick it up gradually. The goal is to finish the last stretch of the run feeling strong and in control, without gasping for air.
5. Hill Running – Short hill sprints build explosive power in your legs, improve form, and speed up your heart rate. They’re good for runners who want to boost their cadence and efficiency. Hills are strength work in disguise.
Other workouts such as Vo2Max, lactate threshold, double threshold etc., require a deeper knowledge of the science and physiology behind them before being tackled. Focus on what you know and understand, not on what the elite Kenyans are doing.
Cross-training is key to remaining healthy while running, especially as you age (Photo Pexels)
But that’s not all there is. To get faster and remain injury-free, you must do work beyond running. Some examples are:
6. Strength Training – Incorporating 2â3 strength sessions per week will make you stronger and, thus, faster. Full-body and compound movements will help with running economy and injury prevention. Think of squats, lunges, deadlifts, and core work.
7. Cross-training â Non-running activities like cycling, swimming, or yoga improve fitness, build strength, and reduce injury risk by working different muscles without the repetitiveness of movement and pounding of running.
8. Plyometrics – These exercises involve jumping and explosive movement to help improve your power and coordination. A few well-timed sets of bounding, hops, or box jumps before your run can sharpen your stride and reduce contact time with the ground.
9. Prioritizing Recovery –Your body needs time to adapt. Without quality recovery, your speed won’t stick, and you’re more likely to burn out or get injured. Sleep well, eat right, foam roll, and stretch as necessary. Gains don’t happen during training, they happen during recovery, where your body adapts and grows stronger.
10. Mental Strategies – Running fast requires mental fortitude. Breaking a tough run into small segments, repeating a mantra, visualizing success or adjusting your thought process may be just as important as the way you train.
Speed work is the exciting part of training, but it only works when done right and is well supported by your solid base. Both elements must work in harmony, complementing each other rather than competing between them. As you start integrating faster sessions into your week, keep your easy runs sacred, your recovery intentional, and your mindset focused on progress, not perfection. When done right, it is this balance what will make you a faster, stronger, and more injury-resistant runner.
Talking about our great workouts and spectacular results is a favorite topic of runners’ conversation. “Johnny’s mile repeats are spot on for a 5K PR!”, “Jimmy is crushing his track workouts.”, “Helen swears by her Fartlek sessions.” So, why am I not doing any of this stuff? Why does my coach have me doing boring stuff?
If you are training for long-distance running, your base is the key. The aerobic base, that is. A skyscraper stands on a solid footing for the same reason the pyramids have stood on their wide bases for 4500 years. They both have a solid foundation to bear the load. The same principle applies to a long-distance runner. Your aerobic base is the foundation of your running. It’s what every training block builds upon, and what ultimately supports your ability to perform. What good comes from running 400 meters in 62 seconds if that is all you can hold, but you are racing a 5K?
To understand the importance of an aerobic base for a long-distance runner, know that even the fittest and fastest Kenyan elite runner runs a marathon 99% aerobically. Even Olympic 5000-meter champions require about a 90% aerobic effort to compete at that level. You’ll likely never be there, but this doesn’t preclude you from the reality of human physiology.
In his “Guide to Coaching”, Coach Steve Magness states: “We have a temptation to want to skip to the ‘cool, sexy’ stuff. It’s boring to do endless easy runs or to spend hours working on the starting position in the sprints. But the ‘boring’ work serves as our foundation. We need a firm understanding of the basics before we move on to the next step. And once we have moved on, we must continually go back to the basics to ensure that they are ingrained.”
Is this clear enough?
The Boring Stuff
It is counterintuitive to accept that you must run slow so you can run fast. Yet this is one of those things you must accept, trust the science, and move forward with if you aspire to become a successful long-distance runner.
The slow (boring) stuff is the key to becoming a strong runner (ChatGPT Image)
Training at slower paces is the foundation of endurance because, among other things, it enhances mitochondrial density (improving oxygen delivery to the muscles), enhances capillary development, and increases fat utilization as fuel, which will make you a more efficient athlete. Low-intensity training also stimulates aerobic enzymes without overstressing the body, allowing more consistent training and better recovery. Over time, these physiological improvements will enable you to maintain faster paces with less effort.
Structured properly within your training, slow runs support speed, stamina and contribute to a better race-day performance. And this takes time. It doesn’t happen by running slow for a week or a month. If you trust the process and keep a written record of your workouts, before you know it, you will be running longer, easier and faster with the same effort. What once was your pushing pace, will now be your warmup pace.
The Sexy Stuff
Now that you have a strong base, we build on it.
Do you want to enjoy the runner’s highs? Build a base (Photo Pexels)
I often compare runners with F1 engines. They can do amazing things, but they require a lot of work, constant modifications and adjustments. The engine is the base, which is solid, but it can’t perform at the expected level without testing, tweaking and failures.
Short intervals, long intervals, Fartlek, mile-repeats, track, threshold, VO2Max, progressions, and so many more are part of the arsenal of workouts you have at your disposal to become a faster runner. These workouts will leave you pleasantly exhausted, provide you with that exhilarating feeling we have learned to love, and get you to enjoy the sweets of a runner’s high.
But be warned. These should be just a fraction of your workouts. You shouldn’t do them day after day after day just because you built a solid base. Maintaining and solidifying the base is a lifetime pursuit. The base of the Eiffel Tower has been constantly maintained since 1889, and thus, still stands strong.
Speed work is essential to becoming a faster runner, but easy recovery runs in between hard workouts and the ubiquitous long run should not be skipped. It should all be in balance.
So, next time your coach asks you to slow down, be patient, or play the long game, understand he/she is not doing so because he/she is mean. There are proven scientific and physiological reasons behind it. So, embrace the boring stuff and become a better, faster runner.
Can you share your slow running experience in the comment box below?
A few years ago, in a Facebook group I belonged to, someone asked for recommendations on what to include in a kit for a 5K she was putting together for some community center. âA tech shirtâ, said someone. âA good bag that you can actually use after the raceâ, stated someone else. âA travel mug with the race logo,â chimed in a 3rd person. As asked, I added my 2 cents: âA pair of custom-made running shoes delivered to my door by Eliud Kipchoge himselfâ.
And I was not being facetious. I was expressing how much I would love for Eliud Kipchoge to personally hand-deliver a pair of custom-made running shoes as part of that 5K. The point was that you may include whatever you want in a race kit, it is just a matter of cost.
For those of us who have been competing for a few decades, races where you only got a bib and traffic control were commonplace. Races with medals, tech shirts, expos, and celebrity participation were the exception. Or they were the exclusive domain of races with a major sponsor, the New York City Marathon, or similar events.
In a recent Runnerâs World Newsletter, they stated that âveterans of the first running boom in the late 1970s and early 1980s love to recount the simplicity of that eraâs races. âSomeone would draw a line in the road, yell âGo!â, and then hand you a popsicle stick with your place as you finished. Entry fees were a dollar or two. The post-race party was a tailgate at someoneâs station wagon.â
Even the convenience of registering online adds to the price of a race (Photo Pexels)
Now we complain if the medal looks cheap, if hydration has no options, if there is no entertainment along the way, if all we get is a banana, if the race shirt design is not to our liking, if there are no finish line professional pictures, if the race kit has only a handful coupons, etc. All great optionsâbut they cost money, and you have to pay for them.
When you have water, Gatorade, or multiple flavors of gels every two miles, understand that it is part of the $80 for 10K or $150 for a half marathon you ponied up. When you go out of your way to thank all police officers for being there, donât forget you paid for their time. This is when you should be mad at a crappy medal, a cotton race shirt, not having a banana, or them cramming age groups every 10 years.
According to that same RW post, âa RunSignupâs 2023 report found that the average 5K cost $29.90. Half marathons in the $100 range are now typical. And in December, 1,000 runners will get boutique treatment (personal fluids, pacers, indoor warmup space, etc.) at The Marathon Project in exchange for a $500 entry fee. Even allowing for inflation and exaggeration, races cost relatively much more than in days of yore. What gives?â
There are always cheap race organizers. The ones who charge premium prices yet donât have crowd control and mix hundreds of runners with regular space users, such as a beach boardwalk. Sure, there are the ones that accommodate a half marathon within the confines of a public park, donât have police control in place, get you a cheap generic award, and have no qualms about overcharging you. You should not participate in those races.
Look. I am not saying âthe old times were betterâ. I am not here to advocate the return of the $15 Boston Marathon. The point here is to understand that you get what you pay for. When racing is labeled as a charity event it is because funds are being raised for a noble cause, not because sponsors want to subsidize your racing ego. So, there are two clear options:
A â Treat every local 5K as if it were a World Marathon Major celebration and demand what you pay for if you donât get it.
B â Accept a no-frills race at a no-frills price and then donât go complaining on Tik Tok about how crappy the medal was.
Do you think race fees are justified? Drop your thoughts in the comments below!
Marathon Training Academy is one of the most popular running podcasts out there. Angie and Trevor Spencer have been teaching and entertaining runners for about 13 years. In December 2022 they celebrated their 400th episode with a potpourri of audio messages from their listeners reminiscing how they got started as runners. They included Coach Adolfoâs audio.
