What to Know about Marathon Pace Before Your Race
April 10, 2024
The marathon distance can be one of the trickier races to pace. 26.2 miles is a long time—a pace that feels comfortable at the start could feel like a death march by the end if you aren’t careful. This article will delve into the science of marathon pace, including how to strategize for a race where you feel good and run your best.
Before diving into the science behind marathon pacing, it is helpful to understand the terminology of race pacing strategies. The three types of pacing splits are positive splits, negative splits, and even splits. Positive splits occur when the first half of a race is run faster than the second half. The implication is that the runner slows down in the second half due to fatigue. Negative splits are when the second half of the race is run faster than the first. Typically, negative splits are minor, such as the second half of a marathon being 30-90 seconds faster than the first half (not 30-90 sec/mile – 30-90 sec per 13.1 miles). Even splits describe consistent pacing throughout the entire race, with the first and second halves roughly equal.
A second common question is: what is marathon pace? Marathon pace is what you can realistically sustain for a full 26.2 miles. For most runners, that is an aerobic, easy-to-moderate intensity. If you start at a pace and can only hold it for 13-14 miles before slowing down, that is not your marathon pace.
A marathon pace strategy draws upon both theory and practice. While science can guide your pace strategy, implementing it requires skill. The more marathons you race, the more you will be able to refine your pacing skills. However, no matter how many marathons you have run, there are some basic evidence-based principles that can guide race day approach.
What factors does the science indicate can actually improve marathon pace?
Most runners know that hitting the wall can occur if you experience glycogen depletion. Too few carbohydrates during a marathon and you will not be able to sustain your pace. On the opposite end of the spectrum, higher carbohydrate intake supports a faster finish time.
One 2014 study clearly demonstrates the positive effects of carbohydrate intake on marathon finish time. When matched for equivalent 10K fitness, marathoners who took 60 grams of carbohydrates per hour finished 4.7% faster (10 min and 55 seconds) than those who fueled freely.
As discussed in a 2022 systematic review, the general recommendations for nutrition during a marathon are 60-90 grams of carbohydrate per hour. The high-carb intake provides a steady dose of substrate (thus steady energy) and reduces fatigue, thus helping you maintain marathon pace for the whole race.
Run less run faster training programs occasionally surge in popularity. These programs may work for some people, but they are not a magic bullet to a fast marathon pace. The science is clear that for your best marathon time, doing (relatively) higher training volume leads to improvement.
Higher training volume does not mean you have to give up everything else to run 80 mile weeks. In 2020 study in Scandinavian Journal of Medicine and Science in Sports, researchers observed that 40 miles per week (65 km per week) led to less of a decline in pacing during a marathon – and therefore a faster average marathon pace.
If your mileage is limited due to injury risk, you can replicate higher volume training with cross-training. For example, I have coached marathoners who ran three to four times per week and cross-trained in the pool or on the elliptical two to three three times per week. Pool running and the elliptical both simulate the movement patterns of running without the high impact.
Related: How to Increase Your Running Mileage Safely
Ask any marathon runner and they’ll tell you that poor weather conditions – heat, rain, wind, etc. – make the race so much tougher. It’s not a matter of mental toughness; weather does impact the pace you can sustain for a marathon.
A 2012 study in PLoS One examined marathon finish times across six marathons (London, Boston, Berlin, Paris, Chicago, and New York). The statistical analysis indicated that the best performances occurred in mild temperatures of 39 to 49 degrees Fahrenheit (3.8 to 9.9 C). Any colder or warmer resulted in a decline in pace, especially when temperatures rose above 60 degrees Fahrenheit (15 C). Once it gets warmer than 60 degrees F/15 C, you want to start modifying your pace by 5 sec/mile or more. Warmer temperatures increase thermoregulatory demands on the body, making it harder to sustain paces without overheating.
Likewise, windy conditions will increase the energy cost of any given speed. Likewise, a 2021 review in Frontiers in Physiology noted that precipitation led to slower finish times, likely due to its impact on thermoregulation.
You can’t control the weather on race. If the weather forecast is sub-optimal, a prudent approach is to adjust your pace strategy for race day.
What tools should you use to ensure you are on track during the race? Generally speaking, there are three tools you can use: a GPS watch or app, a heart rate monitor, or a power meter. Power meters are not very common for running, as the science is not very robust to support their usage. So, most runners use either a GPS device or a heart rate monitor.
GPS is the most direct measure of your marathon pace on race day. GPS watches and apps will directly measure your pace and report it to you at regular splits (such as every mile). In most races, GPS watches are relatively accurate within a small margin of error. GPS apps are slightly less accurate – so if you are aiming for a specific pace, you may have better success using a GPS watch.
However, some big city races may not have the most accurate GPS measurements. The tall buildings and underpasses can interfere with the precision of a GPS watch or app. Instead, you can get more accurate mile splits by manually lapping your watch at each mile marker. If you are worried about forgetting that, consider checking your splits every 5K throughout the race.
What about heart rate monitors? These devices will not directly measure splits, but they can measure your work rate (intensity). Some runners report that using heart rate on race day helps them control their effort in the first half. However, this approach does not work for everyone. Other runners will experience a higher heart rate on race day due to caffeine, nerves, and other factors.
Now that you understand the theories around marathon pace, you likely are wondering: how do you actually put that into practice on race day? Even splits are typically the most effective – but ultimately, your pace strategy should be course-dependent.
Multiple research studies (such as a 2020 cross-sectional study in the International Journal of Exercise Science) demonstrate the efficacy of an even pacing strategy. Likewise, setting a realistic goal pace also contributes to better marathon performance.
Ideally, your marathon strategy should aim for even splits based on a pace that your training indicates is realistic. Even pacing does not mean every mile is exactly the same – you will likely have slight variance based on terrain. What even pacing does mean is that you do not start out with a high level of exertion – or plan to increase pace drastically in the second half.
For example, a runner targeting a 4-hour marathon would aim for 9:00-9:10/mile pace throughout the whole race. Some runners do benefit from a slightly slower start; however, in the scheme of a marathon, starting about 20-30 sec/mile slower than goal pace for one mile can still lead to overall even splits.
One caveat regarding even pacing: it may not be realistic on every marathon course. Some races such as the Berlin or Chicago marathons are flat, lending well to an even pacing strategy.
However, races like New York and Boston are slower and more challenging courses. New York has a hillier first half and a faster second half, meaning that a negative split may be more feasible. Boston has more hills in the second half, meaning that some runners may positively split.
When developing a marathon pace strategy, take into consideration the course you are racing. You may need to strategize based on uphills and downhills throughout. However, no matter the course, know that banking time is never an effective strategy. No matter the terrain, the first half of a marathon should feel lower intensity compared to the second half.
The weather, race terrain, your training, your nutrition strategy, and other factors all impact your marathon pace strategy. Most importantly though, you want to base your goal pace off of a realistic pace. Examine your training and workouts, rather than aiming for an arbitrary time on the clock.
For more guidance, reference these articles:
How to Pace Your Fastest Marathon
How to Set Your Marathon Goal Time
Marathon Pace Workouts
Want more detailed information on pacing strategies for 26.2 miles? Listen to this episode of the Tread Lightly podcast!
