Increasing Durability Through Strength Endurance
Tired legs are the bane of every ultra-runner’s existence. Miles one through twenty feel good. Even miles twenty-one through forty feel okay. However, every runner feels every mile over fifty.
Even for experienced runners’ hills become difficult to climb, often being reduced to hiking. Strides begin to land flat rather than springy. Muscles feel like battery acid flowing through them, causing malfunction in muscles that properly functioned through the first fifty kilometers of the race.
The difference between a good runner and an elite runner is not the feelings of fatigue. The difference is the elite runner’s ability to maintain proper running mechanics and average pace throughout the entire duration of the race.
Take the 2025 Javelina Jundred 100-miler as an example. A snapshot of the men’s podium of Will Murray, David Rouche, and Canyon Woodward, along with Tara Dower at Female One, provides insight:
Each of these runners maintained their pace and running mechanics throughout all 5 laps, managing to only drift 2-to-3 percent in pace from lap 1 to lap 5. Now examine the laps of Male four through six in the standings, along with Female two:
While great performances to make the top ten in a very competitive race, the difference between the podium and Female one and two is clear. It was not pace, especially for Males four and five and Female two. Chris and Caleb finished lap one with the male podium and Beth finish lap one with Tara Dower. The difference was durability.
Males four through six and female two all experienced a pace drift over 11-percent, while the podium and female one had less than 4-percent. Examination of the livestream footage from race day shows the Male podium crossing the finish line with a graceful stride and spring in their step. Males four through six appeared more labored and were landing flatter.
With the difference revealed and the evidence clear, what is the solution? How can we improve to the point of maintaining an effortless springy stride, and less than 4% drift in pace from miles one through twenty to the finish line?
Research detailed in Steve Magnesses book entitled “The Science of Running”, four exercise scientists examined the explosive strength and strength endurance of elite runners against just experienced runners. They tested the vertical jump for explosive strength and a 30-second continuous jump for strength endurance. Unsurprisingly, what they found was elite runners had more explosive strength and better strength endurance than the experienced runners.
After the test, they examined the ground contact times between the two groups over a 400m sprint. What they found was that the elite runners maintained the same quick ground contact times from start to finish, while the experienced runners’ ground contact times increased at the end of the race compared to the beginning of the race.
Now, obviously, 400m is significantly shorter than 31 to 100 miles. However, the same principle that applied to the shorter distance applies to the longer distance. With better explosive strength and strength endurance, quality running form is maintained, and pace does not drift nearly as much.
There are a lot of ways to improve Explosive Strength and Strength Endurance. Here are two suggestions for each:
Explosive Strength:
- Build a heavier 1 rep max back and front squat with a moderately heavy 5x5 routine twice per week for three weeks.
- Perform plyometric exercises, such as bounding and max vertical jump two times per week.
Strength Endurance:
- Perform compound sets with weights. For instance, do 10 reps of a light back squat, 10 reps of a light front squat, then run 800 meters. That is one set.
- Incorporate plyometric exercises immediately after your long run, such as ice skaters, lunges, and bounding.
By improving explosive strength and strength endurance, durability will improve and runners will see less pace drift toward the end of the race.