Predicting Your Marathon Time

The Marathon Crystal Ball: Predicting a Successful Race Day


“Will I achieve my marathon goal?” If I had a dollar for every time I get asked this question, I’d be retired and living on my own private island!

As race day approaches, marathoners get antsy. They wonder/worry if they can hit their goal. After coaching thousands of marathoners, I’ve come up with a few key factors in marathon success. It’s like having a crystal ball where I can look into the future and predict what will happen on race day. Let me let you behind the curtain.

Outside of weather conditions and other things out of your control, here are the six critical factors in whether you will run well in your marathon or not:

1) Stable mileage

Look at your last 10-12 weeks. Was your weekly mileage consistent and stable? In other words, did you have large swings in weekly mileage or was your high week and your low week within 10-25% of each other? If you averaged 45 miles per week but had several weeks at 20 miles and a few at 55 then you had wide swings in mileage from low to high. If, however, you averaged 45 miles with a couple of “down” weeks at 35 miles and a couple of high weeks at 55, then your mileage was more stable with no large swings from highest to lowest.

I’ve found that athletes who were very consistent in their mileage across the last few weeks before the marathon have a certain amount of “strength” that they can pull from in the later miles of the marathon.

2) Long runs

Every runner knows that long runs are key for marathon success but for predicting success, I’ve figured out that it’s not quite as simple as just getting in long runs. In fact, I evaluate marathoners on two types of long runs and not just that they complete them but how they complete them.

First, it’s not that you complete the long, steady runs that make up the bulk of a marathoner’s long runs. Successful marathoners not only build those long runs up but they also notice that those long runs take less and less out of them. And, they begin to recovery much, much faster after them.

For example, if you built up to a 20-22 mile long run (common for faster marathoners) but were really fatigued and sore for 2-3 days after it, that’s not a good sign. Successful marathoners are usually the ones that not only get in the long, steady runs but find that their bodies can better handle these “time on your feet” long runs in the last few weeks before their marathon.

Second, the marathoners who include 2-3 fast finish long runs in their programs – the long runs where you really push it over the last few miles (when you are physically and mentally tired) have a leg up on race day. It’s one thing to run for a long time but an entirely different experience to run hard when tired – something marathoners with time goals always face. This ability will serve you well on race day.

3) Grooving goal pace

Hitting goal pace during training is one thing. Hitting goal pace while being very relaxed mentally and physically is quite another. Marathoners who feel very comfortable and “smooth” while running goal pace workouts are race-ready. After all, goal pace will be required for hours not minutes so athletes who can run as easily as possible at race pace will be fresher later in the race when fatigue sets in.

[All my marathon plans have goal pace workouts across them. For your next training cycle, you can try them for free as part of my Run Team free trial.]


4) Leg durability

Early in a marathon training cycle, it’s very common for your legs to be sore after long runs or marathon-specific workouts. Later in the training cycle, however, successful marathoners notice that their legs feel stronger. They find that their legs don’t get sore anymore, even though their long runs are longer than before, their mileage may be at its highest and their other workouts are of higher quality. This is a very good sign for marathon day. Strong, fatigue-resistant legs won’t let you down on race day. [If you find your legs just don’t have it late in your races, check out our new Marathon Legs strength training program.]

5) Fueling

Factor #5 is fueling. You are going to need to fuel on race day but fueling is a black hole for many marathoners. There are no hard and fast methods to guarantee success. So, it requires some trial and error to find what works for you.

Marathoners who have their nutrition dialed in (usually after some mishaps in training and lead up races) have a great chance at success on race day. And, it’s not just about knowing what you’ll use but you must have a “robust” fueling plan. By robust, I mean one where you get enough fuel for the entire race. It’s all too common that athletes fuel too little across the race then try to make it up as the wall nears only to find that they can’t.

Whether you use a traditional fueling strategy (fast-acting sugars taken frequently) or an alternative fueling strategy (slower-acting carbohydrates like Generation UCAN or have become fat-adapted using a low carbohydrate, high fat diet), you must have it dialed in in race conditions, meaning you know how much to take across the race and how your gut will react when it is also working under duress in the later miles. It cannot be emphasized enough that nutrition plays a very big roll in success on marathon day.

6) Mental toughness

Of my marathons, the ones I’m most disappointed in are the ones where I had a pity party. I just lacked the mental toughness to deal with the high level of fatigue and mental challenge that the marathon brings. When looking at athletes’ preparation, I try to tease out how they dealt with challenging runs (and they better have had some). Do they have a firm resolve or are they easily overwhelmed when things don’t go as planned or are harder than expected? Successful marathoners know how to deal with big mental challenges. When the going gets tough, these marathoners look around and say, “Where did everybody go?” They know how to do hard things and those that are ready for the greatest challenge of their life are on their way to a successful race.

Prediction time

If you’ve been keeping score, you probably passed the test on a few factors but didn’t quite hit the mark on others. What does this mean?

Obviously, if you hit all the factors, then you have the green light on race day. Go for your goal and know you are well equipped. Even though every marathon is tough, you are in great shape and ready.

If you are lacking on 1-2 factors, then you should go for your goal but just know that it’s probably going to get harder than you like later in the race. You are going to have to bring your “A” game in the final 10K to power to the finish line.

Fail on 2-3 factors then you need to be very open to adjusting your goal on race day (or even beforehand). For sure, don’t go out faster than your race pace and be very observant of how you are feeling. If you coast through 15-16 miles and feel good, then stick to your goal. If, however, you find that the first 10-13 miles feel harder than you would like and find that your body naturally wants to run 5-10 seconds slower per mile, then you need to slow down to that more comfortable pace. This is the only way to get to the finish line without falling apart.

If you’re getting tired early on in a marathon, it’s highly likely that it’s not going to get better and you need to listen to your body and slow down. There is nothing wrong with slowing down to ensure a positive marathon day. You may not hit your goal but it’s a lot better than bonking and doing the dreaded survival walk/jog over the last few miles.

Failing on 3 or more factors means you must adjust your goal. You are likely not ready, especially if your goal is a challenging one. Instead, be smart, adjust to a slower pace (usually 5-15 seconds per mile slower than planned goal pace) and set yourself up for a positive race experience, leaving you itching to get to the next one where you can shore up the factors you were lacking and really nail your goal.

Final Thoughts

Now, you don’t have to listen to me and it’s hard to say someone can’t overcome big challenges. I’m just saying that over the years, this evaluation has served me, as a marathon coach and marathoner myself, very well. It allows me to better help marathoners set their goals and improve the likelihood of a positive experience.




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“I got my first Boston Qualifier today with a 21 personal record!”

– Ramona M.