Neuromuscular Fatigue and Recovery: Are Marathon and Trail Running Different?

Although trail and road are two running disciplines, they have distinct characteristics potentially leading to different physiological impacts that have never been examined. The aim of the present study was to compare neuromuscular fatigue and recovery between a marathon and two trail runs of equivalent effort (29 km; ± 1,400 m). Forty-one trained runners, specialized in either road or trail running, performed a simulated treadmill marathon (MARASIM), a simulated treadmill trail run (TRAILSIM), or a trail run in natural conditions (TRAILNAT), depending on their speciality. Neuromuscular fatigue, i.e. changes in maximal voluntary contraction (MVC), voluntary activation (VA) and peak twitch (Tw) of the knee extensors (KE) and plantar flexors (PF), blood markers of muscle damage, jump performance, and force-velocity profile (FVP) were assessed before (PRE), immediately after (POST), one (+1 day), two (+2 days), and seven days (+7 days) following the runs. Muscle pain questionnaires were administered at PRE and during the month following the run. MARASIM showed significantly greater decreases in KE VA (-23.5% vs. -9.2% vs. -13.0%) and jump height (-11.7%; +11.4%; +5.9%, for squat jump), and significantly higher increases in blood markers of muscle damage (+1,726 UI.L -1 ; +641 UI.L -1 ; +363 UI.L -1 ; at +1 day) compared to TRAILSIM and TRAILNAT, respectively. The return to baseline occurred later in MARASIM for KE VA and jump height. Muscle soreness values also returned to baseline earlier in TRAILNAT and TRAILSIM compared to MARASIM. No differences between groups existed in KE Pt and MVC, in any PF neuromuscular fatigue variables, and FVP. Overall, marathon running appears to induce greater acute neuromuscular alterations than trail running, mostly on KE, with a slower return to baseline values.