The past 12 months produced an impressive variety of new studies on endurance science. As participation in marathons, ultras, and triathlons continues to grow, so does scientific interest in the ways exercise can affect performance and health.
I found the following nine studies particularly illuminating.
Successful Boston Marathon Runners Use A Polarized Training Plan
There are hundreds of marathon training plans, and we all invest significant time and effort in blindly following one or another. It would be nice to see evidence of which strategies actually work. Hereโs some.
The paper: โTraining Volume and Training Frequency Changes Associated with Boston Marathon Race Performanceโ appeared in the journalย Sports Medicine.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., Adelzadeh, K., Holtzman, B., Hackney, A. C., & Whitney, K. E. (2025). Training volume and training frequency changes associated with Boston Marathon race performance.ย Sports Medicine. Advance online publication.ย https://doi.org/10.1007/s40279-025-02304-4
Method: Researchers followed more than 900 Boston Marathon runners to determine how they trained during the 12 months pre-Boston. The runners were serious recreational athletes who trained about 40 miles a week, and finished Boston between 3:30 and 3:50.ย
Result: While all runners trained about the same total amount, the fastest of the group followed a more โpolarizedโ approach in the last four months of their buildup. They did fewer total workouts (but more โqualityโ ones) and more cross-training as they gradually tapered toward marathon day.
Take-home message: Donโt try to continually build mileage as race day draws nearer. Itโs smarter to be fresher and better-rested at the start line. Cut down on total training volume, use cross-training for recovery, and focus on quality workouts at or near goal marathon pace.
More here: Boston Study Reveals Surprising Marathon Training Secrets
Second study: Later in the year,ย a randomized trialย published inย Scientific Reportsย gave polarized or pyramidal training plans to 120 runners for their 16-week training block. Those following the polarized approachย โproduced superior marathon performance โ by about 30% despite reduced training volume.
To Beat Injuries, Be Careful With Long-Run Increases
All runners want to avoid injury as much as possible, but itโs not easy. Dozens, if not hundreds, of prior injury studies have found that injury causes are so โmultifactorialโ that itโs hard to say what actually works, and what doesnโt. Hereโs one with a clear, evidence-based guideline.
The paper: โHow much running is too much? Identifying high-risk running sessions in a 5200-person cohort studyโ appeared in theย British Journal of Sports Medicine.2Frandsen, J. S. B., Hulme, A., Parner, E. T., Mรธller, M., Lindman, I., Abrahamson, J., Simonsen, N. S., Jacobsen, J. S., Ramskov, D., Skejรธ, S., Malisoux, L., Bertelsen, M. L., & Nielsen, R. O. (2025). How much running is too much? Identifying high-risk running sessions in a 5200-person cohort study.ย British Journal of Sports Medicine, 59(17), 1203โ1211.ย https://doi.org/10.1136/bjsports-2024-109380
The method: More than 5,000 runners were tracked (via Garmin data) over 18 months to analyze their injuries relative to their training styles.
Result: The most significant injury indicator was the increase in the length of runnersโ single longest run. Any increase greater than 10% produced a substantial jump in injury risk. As increases climbed, so did risks.ย
Take-home message: Be cautious and calculated about increasing the length of your long run. The more graduated your approach, the better your chances of escaping injury.
How Can You Build Your Marathon Muscle Durability?
There used to be three big physiological pillars of marathon success: VO2 max, lactate threshold, and running economy. Now thereโs a fourth, muscle durability (also called muscle fatigue-resistance), and it has become a major new research subject. The question is: How can you train to maintain high running efficiency after youโve covered 20 miles?
The paper:ย โStrength Training Improves Running Economy, Durability, and Fatigued High-Intensity Performance in Well-Trained Male Runners: A Randomized Control Trialโ appeared inย Medicine & Science in Sports & Exercise.3Zanini, M., Folland, J. P., Wu, H., & Blagrove, R. C. (2025). Strength training improves running economy durability and fatigued high-intensity performance in well-trained male runners: A randomized control trial.ย Medicine & Science in Sports & Exercise, 57(7), 1546โ1558.ย https://doi.org/10.1249/MSS.0000000000003685
Method: The research had an impressive design, beginning with 28 well-trained male runners who had equivalent performance bests. The two groups were divided in half, with one continuing normal training for 10 weeks while the other did twice-weekly maximal strength and plyometric training.
Result: Both groups completed the same endurance test before and after training: a 90-minute long run followed by a time trial to exhaustion. The strength and plyo group surpassed the other group in running economy on the long run, and lasted 35% longer in the time trial to exhaustion.
Take-home message: By adding maximal strength and plyometric work to your training, you can improve your โdurabilityโ at the end of long runs like the marathon.
Should You Shorten Your Stride Length?
The merits of a shorter stride length (ie, higher stride frequency) have been proposed for many years. A new systematic review on the topic gave it a strong endorsement.
The paper: โThe Influence of Running Cadence on Biomechanics and Injury Prevention: A Systematic Reviewโ was published inย Cureus.4Figueiredo, I., Reis E Silva, M., & Sousa, J. E. (2025). The influence of running cadence on biomechanics and injury prevention: A systematic review.ย Cureus, 17(8), Article e90322.ย https://doi.org/10.7759/cureus.90322
Methods: The authors analyzed the results of 18 prior papers on cadence (stride frequency) and its effects on biomechanical or clinical outcomes.
Result: A โmoderate increaseโ in cadence (by five to 10 percent) led to reduced loading rates and โimproved lowerย limb alignmentโ that in turn โreduced stress on the tibia, knee, and hip joints.โ Also, increased cadence did not alter running economy negatively, โand, in some cases, enhanced running economy.โ
Take-home message: There are a lot of internet gurus offering spurious running-form fixes. Against that background, a moderately shorter stride seems to offer a twofer: fewer injuries and perhaps improved economy. You donโt have to hit 180 strides per minute. Just aim for a small increase from where you are.
Cold Is Old, But Heat Is Hot
There was a time, which you may remember, when serious marathon runners lowered themselves into an ice-filled tub after hard workouts. This was supposed to speed recovery, but scientific studies produced mixed results at best. The new approach: Get into aย hotย bathtub.
The paper: โLong-term passive heat acclimation enhances maximal oxygen consumption via haematological and cardiac adaptation in endurance runnersโ appeared in theย Journal of Physiology.5Jenkins, E. J., Killick, J., Zerilli, O., Bailey, T. G., Drane, A. L., Marwood, S., Shave, R., & Dawkins, T. G. (2025). Long-term passive heat acclimation enhances maximal oxygen consumption via haematological and cardiac adaptation in endurance runners.ย The Journal of Physiology. Advance online publication.ย https://doi.org/10.1113/JP289874
Method: Previous studies had shown that training in the heat could improve aerobic fitness. But what about justย sittingย in a hot tub? In this research, 10 well-trained runners completed five weeks of normal training with and without additional hot-tub baths (five times a week for 45 minutes at a temperature greater than 40 degrees C).
Result: The hot-tubbing โincreased haemoglobin mass, total blood volume, and left-ventricular end-diastolic volume,โ which boosted subjectsโ VO2 max. Thus, โPassive heat can enhance aerobic performance.โ
Take-home message: Taking a hot bath after running might produce additional training benefits. Be careful about dehydration, and donโt overdo the bath temperature (104 degrees F should do the trick).ย
Moreย here: Hot Baths Boost VOโmaxโNo Exercise Required
Do Super Shoes Cause Injuries โฆ Or Protect From Them?
This is probably one of the hottest debated questions in modern marathon science. Just about everyone has accepted that super shoes can enhance performance. But is this a free lunch, with no drawbacks? This study offers an early perspective. No doubt there will be many more.
The paper: โDoes advanced footwear technology cause or protect against injuries? A 12-week prospective investigation in 195 half-marathon runnersโ was published in the journalย Footwear Science.6Ryan, M., & Farina, E. M. (2025). Does advanced footwear technology cause or protect against injuries? A 12-week prospective investigation in 195 half-marathon runners.ย Footwear Science, 17(sup1), S246โS247.ย https://doi.org/10.1080/19424280.2025.2492279
Method:ย A group of recreational runners engaged in a structured 12-week training period for an upcoming half-marathon was randomly divided into two groups. One group was assigned to train in the Nike Alphafly 3 super shoes, and the other group was assigned to use a Control running shoe.ย
Result: At the end of 12 weeks, runners in the Alphafly 3 reported 53% fewer injuries, and many fewer โclinical pain events.โ An unexpected outcome: Runners in the Alphafly said their shoes felt more unstable at the beginning of the trials, but more stable after three weeks of use.ย
Take-home message: In this study, the Alphafly 3 shoes provided substantial protection from injuries. Of course, every super shoe is different from every other super shoe. A super shoe is only good if it works for you, but it might be worth a bit of experimentation.
How Many Carbs Should You Consume During A Marathon?
The science of in-marathon fueling is expanding rapidly, with some athletes now talking more about their prodigious fueling than their long runs. Caution is always advised here. More isnโt always better, just as a 30-mile run isnโt necessarily better than a 20-miler. This new paper examined high-carb intakes.
The study: โ13C-labelled glucose-fructose shows greater exogenous and whole-body CHO oxidation and lower O2 cost of running at 120 versus 60 and 90 gยทh-1 in elite male marathonersโ was published in theย Journal of Applied Physiology.ย Okay, this research team isnโt going to win any prizes for โbest title,โ but their findings have been highly cited by other endurance nutrition experts.7
Ravikanti, S., Silang, K. G., Martyn, H. J., Johnson, K. O., Louis, J. B., Bampouras, T. M., Owens, D. J., Jones, A. M., Morton, J. P., & Pugh, J. N. (2025). ยนยณC labelled glucose-fructose show greater exogenous and whole-body CHO oxidation and lower Oโ cost of running at 120 vs 60 & 90 gยทhโปยน in elite male marathoners.ย Journal of Applied Physiology. Advance online publication.ย https://doi.org/10.1152/japplphysiol.00665.2025ย
Method:ย Researchers asked eight elite marathon runners (average best time: 2:22) to do a hard two-hour treadmill run under three different fueling conditions: 60 grams of carbs per hour, 90 grams, and 120 grams.ย
Result: The runners performed worst at 60 grams and best at 120 grams, allowing them to burn more carbs and improve their running economy. Important note: โThe incidence of moderate or severe GI symptoms was high in all trialsโ and greatest in the 120 group.
Moreย here: The New High-Carb Study Thatโs Rocking the Running World
So, How Are You Going To Control That GI Distress?
Itโs a serious Catch-22 situation. High-carb fueling can improve performance but can also increase GI distress, which will have an adverse effect if severe. What are you going to do? This paper investigated the best approaches.
The paper: โNutritional strategies for minimizing gastrointestinal symptoms during endurance exercise: systematic review of the literatureโ appeared in theย Journal of the International Society of Sports Nutrition.8Mlinariฤ, J., & Mohorko, N. (2025). Nutritional strategies for minimizing gastrointestinal symptoms during endurance exercise: Systematic review of the literature.ย Journal of the International Society of Sports Nutrition, 22(1), Article 2529910.ย https://doi.org/10.1080/15502783.2025.2529910
Method: The authors reviewed 29 randomized controlled trials, crossover trials, and case studies that investigated the problem of GI distress during endurance events.ย
Result: Itโs complicated. โThe onset of GI symptoms is very complex, and that onset is influenced by a huge variety of factors.โ Every athlete must approach the subject โindividually and thoughtfully.โ
Take-home message: Gut training is one of the most productive approaches and can improve GI tolerance in just two weeks. Use glucose-fructose mixes, not glucose alone. Favor drinks and gels over bars. Follow a low FODMAP diet for 24 hours to six days before a race.
How To Run Like Kilian Jornet
The year ended with an amazing case study report on Kilian Jornet, widely acknowledged as the GOAT of endurance performance. Jornet, now 38, started 2025 slightly injured, but built up to a fast third-place finish in the Western States 100 Mile in June. Then, for a cooldown of sorts, he covered 3,200 miles on bike and foot while running-hiking to the top of 72 โfourteenersโ In Colorado, California, and Washington.
The paper: โPhysiological, nutritional and thermoregulatory responses of a world-class mountain-ultramarathon athlete during the 2025 Western States Endurance Run 100โ appeared in theย Journal of Applied Physiology.9Mougin, L., Jornet Burgada, K., Ely, B. R., Morel, B., Blagrove, R. C., Mix, H., Svendahl, E., Mears, S. A., & Stennett, R. (2025). Physiological, nutritional and thermoregulatory responses of a world-class mountain-ultramarathon athlete during the 2025 Western States Endurance Run 100.ย Journal of Applied Physiology. Advance online publication.ย https://doi.org/10.1152/japplphysiol.01048.2025
Methods: With Jornetโs full assistance, researchers measured his energy expenditure and intake during the Western States 100, as well as his heart rate, GI temperature, weight, and kidney function. This was done with precision because Jornet swallowed doubly-labelled water and ingestible microprobes before the race.
Results: So many that they canโt all be summarized here. Jornet burned 16,104 calories in 100 miles, but was only able to replace 40% of that amount by fueling in-race. Most impressively, he switched and increased his fueling as the race progressed. He began by consuming a 50% fat, 50% carbohydrate fuel mix that included real foods and provided about 60 grams of carbohydrates per hour. As the miles added up, he transitioned to an all-carb approach that provided 110 grams of carbs per hour.
Jornet drank about 0.87 liters of fluid per hour and lost 4.3% of his body weight by the finish. He showed excellent pace control, keeping his effort high without pushing too hard at any particular time. As a result, he slowed by only 15% from early stages to later stages, about half the decline of his fellow racers.
His kidneys exhibited signs of exercise stress, but it was transient.
Take-home message: First, there isnโt one. Jornet stands alone. Second, in this era of high-carb-fueling, everyoneโs talking about Jornetโs โmetabolic flexibilityโ-the way he was able to switch fuels over the course of 100 miles. Others will surely try to find their own similar-but-different paths to optimal calorie intake.
Taken together, these studies point in a clear direction: smarter training beats more training, durability matters as much as fitness, and context is everything. The science isnโt telling runners to chase trends, but itโs giving them better tools to make informed decisions.
