A new study by Boston Marathon experts has yielded some surprising training insights. The paper investigated how veteran Boston Marathon runners train and improve in the 12 months before the annual mid-April classic.1DeJong Lempke, A. F., Ackerman, K. E., Stellingwerff, T., Burke, L. M., Baggish, A. L., d’Hemecourt, P. A., Dyer, S., Troyanos, C., Saville, G. H., Adelzadeh, K., Holtzman, B., Hackney, A. C., & Whitney, K. E. (2025). Training Volume and Training Frequency Changes Associated with Boston Marathon Race Performance. Sports Medicine. https://doi.org/10.1007/s40279-025-02304-4
It found that more training and harder training yield consistent benefits—a result that won’t impress anyone.
However, it also concluded that cross-training can play an important role in the final months of marathon training. In addition, a reduced number of weekly run sessions led to faster times.
In other words, a smart marathon taper period is essential. If you don’t get this part of your training right, you might waste all your previous hard work.
As the paper’s authors stated: “Training programs marked with a relative taper, including reduced running days, were associated with better performance.”
Marathon Training For “Real Runners”
Many, if not most, other marathon-training articles and papers focus on elite runners who log 100-mile weeks and grab podium positions in World Marathon Majors. This research is different.
It’s about serious but non-elite runners who train hard to chip away at their marathon PRs. It’s also a big paper that followed 917 subjects, more than half of whom were women.
Subjects had an average age of 47, had run an average of nine previous marathons, and logged about 40 miles a week in training. The research team termed them “trained developmental” runners. The subjects finished the 2022 Boston Marathon in 3:35 (average male time) and 3:53 (average female time).
The Two Important Slices Of Marathon Training
The paper took a simple, big-picture approach to its investigation of marathon training. First, it asked subjects how they had trained over the 12 months preceding the mid-April Boston Classic.
Researchers then took this data and divided it into two “buckets.” How did the runners train from 12 months before Boston to 4 months before (12-4); and how did they train in the last four months (4-0)?
The paper was written by a large team of Boston Marathon sports medicine experts who have been steadily releasing new data on marathon running. Most of their previous work has focused on injuries and health issues, including gastrointestinal problems2Kelly, M. R., Emerson, D. M., McDermott, B. P., Atkins, W. C., Butts, C. L., Laursen, R. M., Troyanos, C., Duckett, A., & Siedlik, J. (2023). Gastrointestinal cell injury and perceived symptoms after running the Boston Marathon. Frontiers in Physiology, 14, 1268306. https://doi.org/10.3389/fphys.2023.1268306 and heat stroke..3Breslow, R. G., Collins, J. E., Troyanos, C., Cohen, M. C., D’Hemecourt, P., Dyer, K. S., & Baggish, A. (2021). Exertional Heat Stroke at the Boston Marathon: Demographics and the Environment. Medicine and Science in Sports and Exercise, 53(9), 1818–1825. https://doi.org/10.1249/MSS.0000000000002652
The new paper instead focused on the connection between training and performance.
The Numbers Tell The Story
Here are the analysis and numbers you’re most interested in, as reported in the new Boston Marathon training study.
During the 12-4 period, an additional running session per week improved race time by about 3.6 minutes. An additional quality session/week improved race time by about 16.2 minutes. Quality training included pickups, tempo runs, speed work on the track, etc.
During the 4-0 period, an additional run/week improved race time by about 3 minutes. An additional quality run improved race time by 17 minutes. Plus: a one-day increase in cross-training/week improved race time by 6 minutes.
The runs/week analysis got thorny in the 4-0 period.
When researchers accounted for the running experience of their subjects, it turned out that fewer runs, and not more, led to faster race times. “Participants who reduced their number of weekly running sessions” improved their race times by 3 minutes.
These findings led researchers to conclude: “Faster race times were associated with higher overall training volumes, more speed-focused running sessions, more cross-training, and a relative reduction in running volume in the 4–0 months leading up to the race.”
The paper’s authors also noted that similar findings had been reported by a paper titled “World-Class Long-Distance Running Performances Are Best Predicted By Volume Of Easy Runs And Deliberate Practice of Short Interval And Tempo Runs.” 4Casado, A., Hanley, B., Santos-Concejero, J., & Ruiz-Pérez, L. M. (2019). World-class long-distance running performances are best predicted by volume of easy runs and deliberate practice of short-interval and tempo runs. Journal of Strength and Conditioning Research, 35(9), 1. https://doi.org/10.1519/jsc.0000000000003176
You can find other helpful marathon-training articles here and here. The first covers general principles of marathon training, and the second points out common training mistakes you’ll want to avoid.
Expert Answers To Key Marathon-Training Questions
In the section below, first author Alexandra DeJong Lempke answers questions about the new Boston Marathon training research. DeJong Lempke is an assistant professor of physical medicine and rehabilitation at the Virginia Commonwealth University School of Medicine and has a best marathon time of 3:35:51.
MH: This is a big paper with a lot of subjects, data, and statistical analysis. What’s the most explicit summary statement you can make about the most important results?
ADL: We found that runners who had overall higher training frequencies and intensities in the 12-4 and 4-0 months pre-race had better performance outcomes compared to runners who reported habitually lower levels of training. Importantly, a relative reduction in the number of weekly training sessions in 4-0 months compared to 12-4 months was associated with improved performance.
MH: You didn’t ask your subjects specific questions about long runs, which many marathoners consider the most essential piece of marathon training.
ADL: That’s right, but it’s certainly something we plan to ask in the future. We’d like to drill down and ask more questions about long runs, and also about quality sessions like hill training, fartleks, track sessions, etc. The present study drives home the message that mileage alone does not tell the full story about training load.
MH: Would you agree that your results support a “polarized” approach to marathon training?
ADL: Yes, we believe that our results align most closely with the polarized training model. Runners who improved their performances built a strong training base during months 12-4, then did fewer sessions but with greater intensity during 4-0, and also did more cross-training at that time. Those who did relatively fewer weekly sessions during 4-0 then had improved performance.
The important piece here is the relative changes in training. Runners should not ramp up activities during their taper. They should plan a training program that allows them to support changes during the taper.
MH: Your paper supports more cross-training in the 4-0 months, but doesn’t provide any advice on whether it should be strength training, cycling, elliptical, or any specific type of cross-training. What are your personal observations in this field?
ADL: You’re right about the lack of cross-training advice. This is something we hope to study in the future.
In my view, there have been many studies that support strength and plyometric training for improved running economy. A good one is the systematic review of randomized controls by Balsalobre-Fernández and colleagues.5Balsalobre-Fernández, C., Santos-Concejero, J., & Grivas, G. V. (2016). Effects of Strength Training on Running Economy in Highly Trained Runners. Journal of Strength and Conditioning Research, 30(8), 2361–2368.
While running is a very linear sport, I am personally a proponent for incorporating movement variety into resistance workouts to build supporting muscles and power.
I have also observed that replacing some runs with low-impact biking and swimming endurance options can increase the overall volume of training with little injury risk. This notion of cumulative volume aligns with our finding that reducing weekly run sessions while adding cross-training sessions in the four months pre-race can improve performance.
The big take-home message for runners is that they should not train themselves into the ground with high mileage, but focus more on fueling and recovery to support race-day success.
MH: Why do you think so many coaches and runners worry about getting stale during a taper?
ADL: There are probably several reasons for this feeling. When some runners reduce mileage, they may think: “I’m training less, I must be getting out of shape.” This isn’t just psychological. There is also a change in the neural stimulation runners get when training less.
But they must remind themselves that the taper is essential for muscle recovery and for increasing muscle energy (glycogen). Muscle glycogen gets depleted by endurance activities, so runners who maintain their training all the way up to race day may hinder their performance.
The Smart Road To Marathon-Training Success
When you begin your next marathon-training program, here are several key points to remember:
- Take a long-term view so that you can make appropriate changes, particularly during the last month or two of your training.
- Do as much long, easy training as you can, but also sprinkle in harder days when you are appropriately recovered for them.
- Run a little less frequently during the last stage of your marathon training so that you can take more recovery days.
- Continue that “sprinkle” of harder days, and consider adding more cross-training.
- Lastly, taper for several weeks to make sure your leg muscles are as healthy as possible, and your glycogen supply is optimally loaded.
For a deeper dive into periodization, check out this next guide:
