Neuromuscular Fatigue and Recovery: Are Marathon and Trail Running Different?
Medicine and science in sports and exercise · 2026
Marathoners showed more central fatigue and muscle damage than trail runners at matched effort, but non-random, specialty-based groups confound the comparison.
Part of: Hamstring and muscle injury: rehabilitation and return to play · Calf and Achilles injuries: from strain to rupture · Training load and injury risk: what the evidence says · Endurance performance and physiology: training the aerobic engine
The paper
Quasi-experimental comparison, n=41 trained runners (road vs trail specialists), comparing neuromuscular fatigue and recovery after a simulated marathon versus trail runs of matched effort.
What they found
Marathon running produced larger central fatigue and muscle damage than trail running of equivalent effort: knee extensor voluntary activation fell -23.5% after the marathon versus -9.2% and -13.0% after the two trail conditions, squat jump height dropped -11.7% after the marathon but actually rose +11.4% and +5.9% after the trail runs, and blood muscle-damage markers rose by 1,726 vs 641 vs 363 UI/L at day 1. Marathon runners also took longer to return to baseline for activation, jump height and soreness; no group differences were found for plantar flexor fatigue, knee extensor MVC/twitch, or force-velocity profile.
Study design
Quasi-experimental, prospective, between-group comparison, not a randomized trial: 41 trained runners were allocated to a simulated treadmill marathon, a simulated treadmill trail run, or a natural trail run according to their own pre-existing specialty (road vs trail). This sits at the level of a small controlled mechanistic physiology study, well below an RCT or cohort with independent exposure assignment.
Methodology
Group assignment tracked each athlete's own specialization rather than randomization, so the 'discipline' comparison is confounded with 'runner type': trail specialists likely carry a repeated-bout protective adaptation to downhill/eccentric loading that road specialists lack, which alone could explain much of the damage difference. With roughly 13-14 runners per group and many outcome variables (MVC, voluntary activation, twitch, two muscle groups, blood markers, jump, force-velocity profile, soreness), multiple-comparison false positives are a real risk, and the abstract gives percentage changes and absolute values but no p-values, effect sizes or confidence intervals to judge robustness. Pooling a natural trail run with a simulated treadmill trail run as equivalent adds further noise. The neuromuscular testing (MVC, voluntary activation, twitch interpolation) is lab-standard and credible, and follow-up to 7 days (soreness tracked a month) is a genuine strength for a fatigue-recovery question.
The appraisal
The within-marathon-group changes, roughly a 23% activation loss, a large creatine-kinase-type rise, and slower recovery, look physiologically real and plausibly meaningful for recovery planning, but the between-discipline comparison is an association between group type and outcome rather than an experimentally isolated effect of terrain or running mode itself. The trail groups' squat jump height rising rather than falling post-effort isn't necessarily noise: a transient post-exercise potentiation effect from sustained submaximal activity is a recognised phenomenon and a more parsimonious explanation than measurement error, though it does mean the jump-height contrast between disciplines may say as much about acute neural facilitation as about muscle damage.
The gap
Without randomizing runners across conditions, or at minimum matching training history and prior eccentric exposure, there's no way to tell whether the marathon-trail difference reflects the discipline itself or simply that trail specialists are conditioned against the damage their sport usually inflicts.
Landmark context
This builds on the French exercise-physiology tradition (work from groups including Millet, Temesi and Degache) that used voluntary activation and twitch interpolation to show marathon and ultra-trail running cause measurable central and peripheral neuromuscular fatigue; this study is one of the first to pit marathon against effort-matched trail running head-to-head within a single experimental framework rather than studying each discipline separately.
What to do Monday
Not something to change Monday's practice on: it's useful background for counselling marathoners that central fatigue and damage markers may run higher and recover more slowly than in trail runners after a similarly demanding effort, but the confounded design means you shouldn't yet advise switching disciplines on the expectation of less post-race damage from terrain alone.
In practice
This applies to runners moving between road marathons and trail races, and to the physios and S&C coaches managing their post-race load. In the clinic, expect marathoners to carry central fatigue and elevated CK-type markers for longer than trail runners of matched effort, so push return-to-plyometric and high-speed running work out towards day 7 rather than day 2 to 3 after a flat marathon, and track the soreness trajectory rather than assuming it mirrors a trail runner's faster bounce-back. On the performance floor, don't sell 'trail is gentler on the legs' to a road specialist thinking of switching disciplines for recovery's sake: the faster recovery seen here in trail runners is most likely their accumulated eccentric-load tolerance talking, not the terrain itself, so a road runner new to technical descents should still be loaded cautiously. If you want an objective readiness marker rather than guesswork, baseline a countermovement jump before the event and retest at 48 hours and day 7, using the return towards baseline height, not just RPE or soreness, as the trigger to progress plyometric and sprint loading.
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