REF-319 · Winn BJ, Haight DJ, Williams DSB 3rd & Kirby BS, 2025 · European Journal of Applied Physiology, · Paper · PubMed

Skeletal Muscle Elastic Modulus in Marathon Distance Runners

In 80 runners at a World Marathon Major, pre-race rectus femoris stiffness was LOWER in competitive than recreational runners (13.0 vs 15.6 kPa) and in the fastest than the slowest finishers (11.6 vs 16.9 kPa; r = −0.40 with finish time); the marathon raised stiffness ~23%, less in runners wearing plated, highly cushioned shoes (~17% vs ~31%)

Blimited evidenceMeasured on recreational to highly trained athletesWritten before October 2026, being re-checked

Participants

n=80 marathon runners (30 female, 50 male) running a World Marathon Major

Protocol

Rectus femoris shear modulus by ultrasound shear-wave elastography before and after the marathon
Experience level, muscle soreness and run readiness surveyed
Comparisons by competitive vs recreational status, finish time and footwear

Key Results

Pre-marathon shear modulus lower in competitive than recreational runners: 13.0 ± 4.6 vs 15.6 ± 5.6 kPa (P = 0.0014)
Lower in the fastest than the slowest finishers: 11.6 ± 3.0 vs 16.9 ± 6.5 kPa (P < 0.0001); associated with finish time (r = −0.40, P < 0.0003)
The marathon raised shear modulus by ~23% regardless of experience, sex or course; among runners with matched finish times, though, the increase was smaller in those wearing highly cushioned plated shoes (Vaporfly ~17% vs Other ~31%)
There was a strong association between muscle soreness and run readiness (R² = 0.995, P = 0.0026)
Marathon recovery time was longer in runners with greater marathon-induced increases in shear modulus

Mechanism

The authors read the modulus as a non-invasive surrogate for muscle damage: it rose after the race in everyone, and rose more in those who then took longer to recover. The lower resting modulus in competitive and faster runners is consistent with long-term adaptation to repeated running load, but the design is cross-sectional for that comparison — it may also reflect factors before or after the marathon such as exercise capacity or recovery time (the authors say both).

Practical Application

In 80 marathon runners, resting rectus femoris stiffness was lower in the competitive (13.0 vs 15.6 kPa) and in the fastest (11.6 vs 16.9 kPa) runners and correlated with finish time (r = −0.40); the race itself raised stiffness ~23%, and runners whose stiffness rose more took longer to recover
Plated, highly cushioned racing shoes roughly halved the stiffness rise at matched finish times (~17% vs ~31%) — one measurable way the shoe changes the muscle cost of a marathon
A LOWER resting stiffness went with the better-trained, faster runners here; a large post-race jump went with slower recovery — so both the level and the change carry information
Inference, not tested: tracking one's own resting stiffness over a build would show whether it trends toward the "competitive" pattern; this study measured each runner only before and after one race, not over training weeks
Not from this paper; the base's own practice: after a marathon, give runners with an unusually hard-hit, stiff quad more recovery days than the calendar default; the study reports the association but not a cut-off

Limitations

Only rectus femoris measured; SWE, not myotonometry
Cross-sectional baseline comparison (not longitudinal training tracking); one race
Marathon-specific — cycling stiffness patterns may differ
How this entry was checked and changed
Why this level

regraded 2026-09-27 from A-: observational pre-post / cross-sectional, n=80 (<100)

Content correction 2026-09-27
Added abstract results missing from the entry: fastest vs slowest finishers (11.6 vs 16.9 kPa), the footwear effect (~17% vs ~31%), and "irrespective of experience, sex or course".
"Could use myotonometry to track adaptation" -> the study used shear-wave elastography; the tracking idea relabelled as untested inference.
Tier 4-5 (Elite) -> Tier 1-3 (recreational and competitive marathoners); Sport "cycling, running" -> running; Level A- -> B (observational, n=80).