Marathoners: are your easy runs more important than workouts?
A new study shows that faster marathon runners log three times the mileage of slower runners–nearly all of it consisting of easy runs

The difference between you and the fastest marathon runner in the pack on race day might not have anything to do with genetics or speed, according to a new study published in the Journal of Sports Medicine. Strava data from more than 100,000 runners of various performance levels were analyzed, and show the fastest runners ran three times more than the slower runners in training–and this extra volume was heavily composed of low-intensity running.
Should you cool it on the workouts and shift your focus to easy runs?

The study involved 119,452 participants and their 151,813 cumulative 42.2km runs between 2014 and 2017; the date, times and locations of these runs coincided with those of major marathons. Researchers analyzed Strava activity data recording during the 16 weeks leading up to the race and organized data into easy (Z1), threshold (Z2) and high (Z3) intensity zones.
Researchers analyzed the data in two categories: gender (male and female) and age (over 40 and under 40), and all groups demonstrated a positive correlation between speed and training volume, shown in the graph below. (Graphs for all groups displayed the same overall pattern.)

Faster runners run more
It became immediately evident that as training volume decreases, marathon completion time increases. The fastest runners, who clocked 120-150 minutes, accumulated three times the mileage of the slower runners, who logged times exceeding 240 minutes. The faster group had an average weekly mileage of about 107 km, whereas the slower group recorded an average of about 35 km per week.
Most runners in the study used a pyramidal training intensity distribution (TID), where the majority of training (about 80 per cent) was completed at the lowest intensity (Z1), more than 10 per cent in Z2 and the remainder in Z3. This means that a runner logging 107 km per week during their marathon build using a pyramidal TID approach is completing about 86 km in Z1, and split the remaining 21 km between Z2 and Z3.
Faster runners run easier
As marathon speed increased, researchers observed a trend of greater adoption of this training method, with usage rising to 80 per cent among the fastest group. This is shown in the graph below, with green representing Z1, yellow Z2 and red Z3. While time spent training in zones 2 and 3 remained relatively constant throughout the dataset, the time spent in Z1 increased signficantly for runners at the faster end of the spectrum.

Elites versus sub-elites
The study notes that for elite athletes, training is their full-time job, allowing them to contribute more time to easy runs and achieve high training volumes of 160 to 220 km per week. In contrast, sub-elite runners can face challenges in balancing training with full-time jobs, making it difficult to log comparable mileage. As a result, these athletes might compensate for the low volume with higher-intensity training.
These findings emphasize that training volume and time available for training are key factors contributing to the performance gap between elite and sub-elite marathoners.