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 a WhatsApp running group, one of our friends recently shared an article from Menâs Journal Magazine praising the benefits of training in a fasted state. The sub-title alone was promising: The Science-Backed Benefits of Running on Empty, by Spenser Mestel.
I opened it as I thought of how pseudo-science has affected even the most mundane, easy runs lately. Most come from unqualified social media influencers or studies commissioned by companies that will benefit from their results. Dr. Tim Noakes is famous for questioning Gatoradeâs science-based recommendations about the benefits of consuming Gatorade. And like that, examples are plenty.
Running on empty has its scientifically proven benefits (Image by ChatGPT)
We tend to forget that humans have been running for thousands of years. Hunted gatherers did so for hours while chasing an animal until it collapsed. Yet, they were able to pick it up and take it home to feed their families. They didnât carry water packs to replenish every drop of sweat. They didnât carry chews or gels to replace every calorie they burned.
Sure, we have evolved in those thousands of years. The bushmen of the Kalahari were not used to spending their day under air conditioning, sitting in front of a computer, or wearing shoes before they went hunting. But we havenât entered devolution either. Our bodies were built to withstand a certain level of dehydration and caloric deficit.
I want to leave no room for doubt that I am not advocating against electrolyte replenishment, chews, gels, or any other product. God knows I could not have finished my last few marathons without the help of Maurten gels. What I am advocating against is their overuse, to the point where our bodies become unable to learn how to use their own resources.
Running on an empty stomach is not a fad passed around by social media influencers. Based on the article in question and the study on which it was grounded, it is a well-rounded premise that âfasted cardioâ and âlow-glycogenâ training are similar but distinct practices that can offer real metabolic advantages if done right.
While skipping breakfast can be beneficial, you don’t have to do it for every run (Photo Pexels)
Mestel brings in Professor Richard J. Bloomer, Dean of the College of Health Sciences at the University of Memphis, to clarify the lingo. According to him, a âfasted stateâ can simply mean not eating for 10â12 hours, like overnight. But low-glycogen training goes further. It implies depleting your muscle glycogen stores, typically by limiting carbs over a longer period. Both approaches can shift your bodyâs fuel source away from sugar and toward fat, especially during lower-intensity sessions.
According to the study, these are some of the benefits:
Fat Adaptation: By skipping that pre-run snack or breakfast, your body is nudged into burning fat for fuel. Studies cited in the article showed that both men and women increased fat oxidation after exercising in a fasted state. Simply put, youâre teaching your body to tap into a steadier, more abundant fuel source.
Less Stomach Drama: Fasted runs can reduce gastric discomfort for those with fussy guts. No food means nothing sloshing around in there. Itâs a win for morning runners whoâd rather not eat at 5:00 AM just to avoid bonking at 6:00.
Convenience: This one isnât science; itâs life. Rolling out of bed, lacing up, and getting it done before breakfast is just easier sometimes.
The science goes even deeper. In a 2010 study from the Journal of Applied Physiology, Beneficial Metabolic Adaptations Due to Endurance Exercise Training in the Fasted State by Van Proeyen et al., this wasnât anecdotal evidence; it was a tightly controlled experiment. Two groups trained identically on bikes for six weeks. One ate carbs before and during workouts; the other trained fasted.
The result? While both groups got fitter, the fasted group showed superior metabolic adaptations. Their muscles improved at burning fat, their ability to use stored fat (even deep in the muscle) improved, and they kept blood sugar stable over long workouts. The carb-fed group? They didnât show those perks.
Conclusion
It is not about skipping breakfast forever or starting every workout on an empty stomach. But if you mix in a couple of easy runs each week without eating beforehand, especially when effort is low and stakes are even lower, your body might thank you. Youâll become more metabolically flexible, able to use fat when needed and carbs when it matters most.
Donât go overboard. Itâs about teaching your body to adapt so it can rise to the occasion, whether chasing a PR or just running for joy.
Curious to try it? Leave a comment and let me know your experience. And donât forget to subscribe to the Foultips.Run newsletter by clicking the button below.
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?
While there is no magic workout, the long interval workout is mandatory if you want to run longer and faster. There are many iterations of the long interval, but to me, there is nothing like the mile-repeat. It is challenging yet not unconquerable. It is long but not unending. You can start with a few reps and progress to as many as you can handle. If performed at the right pace, you can recover and do it again right away. And if all that wasn’t enough, it hits all the systems.
Mile-repeats can be executed on track or road and properly executed, it will do wonders for your speed and endurance (Photo: Ernest Flowers, Pexels)
I remember reading Alberto Salazar’s autobiography many years ago. He was adamant that this was his key workout from his high school days to his time at the top of the world’s elite marathoners. Since then, I have performed it and prescribed it to my trained runners. The results have always been palpable.
 A mile repeat improves your cardiovascular system while upgrading your endurance and speed. Cadence is increased, mental toughness is developed, and physiological indicators such as VO2Max and lactate threshold are enhanced. Because you are performing at a high rate of energy consumption, the brain ensures that wasted movement is kept to a minimum, resulting in better running form.
 Mile repeats are more than hauling ass one mile as fast as you can go. Anyone can do that. The key is to understand the purpose of the mile you are running. This will determine the pace and effort in which it should be performed.
 Benefits of mile repeats include:
 âș Speed Increase: When performed at race pace or even faster, you are stressing your multiple systems and teaching your body to withstand harder efforts for longer. You are also teaching it how to recruit additional muscle fibers when the usual ones are beaten up.
âș Pace learning: Because we run mostly at an easy pace to maintain and improve our aerobic base, learning how to reach, feel, and maintain our race pace is key. Mile repeats are a perfect way to get there before starting to extend the race-pace mileage. The key is to be constant at the desired pace and not believe that faster is necessarily better.
âș Endurance improvement: Running roughly at the pace you could sustain running all-out for one hour (Tempo) will improve the amount of oxygen you can consume at max effort (VO2Max) and push the line in which your body is unable to use lactate to fuel itself and become unable to clear it, thus triggering fatigue (Lactate Threshold).
The keys to the mile-repeats workout are being constant and keep the movement going (Photo: Mikhail Nilov, Pexels)
In a recent article in the Marathon Handbook website, Amber Sayer stated a great point to be considered when executing this workouts: “The longer your race (half marathon or marathon, for example), the earlier in your training program you can do mile repeats at race pace, because a mile is a significantly smaller percentage of the overall distance.”
And mile repeats don’t need to be performed on a track necessarily. I wrote a post on that issue, which you can read by clicking here.Â
 Executing your mile repeat workout safely and properly requires certain preparation:
 âș Know and understand your workout: It is imperative to be prepared for a difficult workout, so you won’t have the mental space to improvise. Know how many reps you have, what your recovery time is, what is the pace and what is the purpose of this workout. This will predispose you to a successful effort.
âș Warm- up properly: You will be performing a hard workout. You must prepare your body for it not only to avoid injury (as if that weren’t enough reason) but also to make sure you can reap maximum benefits. If you want to read more about the value of the warm-up, click here.
âș Keep it constant: Running the first 400 meters in 1 minute, 2nd 400 in two minutes, 3rd in 3 minutes, and 4th in four is not a 10-minute mile. It is a shitty, worthless mile. Maintain your effort and pace as consistently as possible. This is what’s going to make you better, not a one-off 400-meter stretch at world record pace. Consistency and frequency are what will reap the most benefit for your effort.
âș Continuous movement: You will be tired once your mile is done. Of course, don’t stop, collapse, or sit down. Keep moving. This is the closest you will replicate the demands of a race. I recommend a light jog in between miles, but if this is too much, walk until you catch your breath and then jog. The point is to continue moving forward as you recover and get ready for the next rep.
âș Focus on your current rep: Stay focused on the mile repeat you are executing right now. Don’t dwell on the last one being too fast or too slow. Don’t think about what will happen after this one. You are executing this one now, and it must be executed properly. Thus, it is the only one that matters.
âș Cooldown: You performed a hard workout. Your body is in overdrive. You are tired, exhilarated, most likely amid a runner’s high. This is not the time to jump in the car and go home. A mile or two of easy running will help blood flow. Muscle recovery, and removal or metabolic byproducts. If you want to read more about the value of the cooldown, click here.
 Make sure you add this workout to your training repertoire. The benefits will surprise you.
As you prepare to reap the benefits of your hard weeks of training. Or you may be wondering if you have done enough to hit the starting line in PR shape. Or as you realize you have screwed up your training and will have to wing it. If you plan to race hard, or long, you will need to taper.
Taper (or tapering) is the label commonly used to identify the short training cycle between the end of our race-focused training cycle and race day. The word taper is an intransitive verb. According to the Merriam-Webster Dictionary, it means “to become progressively smaller toward one end. To diminish gradually.” In running, that’s exactly what we are referring to. We start reducing our workload as race day approaches. But why?
Our bodies usually take 14-20 days to adapt to whatever we do in training. If we ran 20 miles today, we are not better for it tomorrow. As our body recovers, it adapts to the benefits of such stressful events and thus becomes stronger. This is why whatever we do in the last two, maybe three weeks before race day, will be of little or no benefit.
There is nothing to gain during taper, but everything to lose. Many races have been ruined by not taking the taper seriously. Don’t become a victim.
Meb Keflezighi has a great quote that epitomizes the last few paragraphs: “It is better to be 90% ready and make it to the starting line than panic and become overtrained or be unable to start the race.”
According to Jess Movold, in a 2024 article in Runner’s World magazine: “Tapering is one of the most critical parts of any marathon training plan, but in many cases, it’s also one of the hardest to implement. Ever heard of the taper tantrums?”
In my personal experience, I’ve felt better with a 2-week taper. But if the fatigue accumulation really beats you up and feel like another long run will destroy you more than help you, an additional week is beneficial.
Theories abound about how to handle the taper, but the scope of this blog post does not include analyzing any models. It wants to point out a handful of errors and misconceptions you may incur that will eventually negate your training gains.
While on taper, be on the lookout for the following so you don’t ruin your race:
I know I picked this up from Instagram, but I donât know the source I should credit.
1.   Follow the original plan: If you got here with your plan, then this is not the time to improvise, regardless of how confident you are or not about attaining your goal.
2. Don’t try one more long run: There is no place for it. It will add to the fatigue, hinder your recovery, and won’t produce adaptations in time for race day.
3.   Focus on nutrition: Avoid detoxes, new supplements, weight-shedding schemes, carb unloading/loading protocols, and indulgent eating. Eat clean and enough.
4.   Tapering means you are still training: You shouldn’t think you can stop because it’s tapering. It is still part of the training program, and it requires work.
5.   Manage your excess energy: With the decrease in activity, as your body rests and recovers, you will bounce off the walls. Expect it and control it.
6.   Take the extra sleep: Your body is repairing itself, so it may ask for more sleep than usual. Don’t skimp on sleep. It is the best recovery tool.
7.   Control your training effort: Because you’ll feel energized, compared with the last few months, it is easy to push harder and even perform your race effort before the actual race. Don’t!
8.   Focus on the main goal: Everything you do must serve your race. This is not the time to try new stretches, foods, gels, shoes, or routines. Stick to what has worked so far.
9.   Strengthen your immune system: Your body is working overtime to repair itself, so your immune system is low. Be proactive. It is no time to get sick.
10. Tread carefully: Be extra cautious as you transit through life. Don’t take unnecessary risks. Don’t climb ladders, jump the sidewalks, text while walking, or rearrange furniture. All that can wait.
Please like this post and share any recommendations from your previous experiences in the box below. Let’s build a community of informed and prepared runners.
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Our bodies usually take 14-20 days to adapt to whatever we do in training. If we ran 20 miles today, we are not better for it tomorrow. As our body recovers, it adapts to the benefits of such stressful events and thus becomes stronger. This is why whatever we do in the last two, maybe three weeks before race day, will be of little or no benefit.