title: Acute and delayed peripheral and central neuromuscular alterations induced by a short and intense downhill trail run.
abstract: Downhill sections are highly strenuous likely contributing to the development of neuromuscular fatigue in trail running. Our purpose was to investigate the consequences of an intense downhill trail run (DTR) on peripheral and central neuromuscular fatigue at knee extensors (KE) and plantar flexors (PF). Twenty-three runners performed a 6.5-km DTR (1264-m altitude drop) as fast as possible. The electromyographic activity of vastus lateralis (VL) and gastrocnemius lateralis (GL) was continuously recorded. Neuromuscular functions were assessed Pre-, Post-, and 2-day Post-DTR (Post2d). Maximal voluntary torques decreased Post (∼ -19% for KE, ∼ -25% for PF) and Post2d (∼ -9% for KE, ∼ -10% for PF). Both central and peripheral dysfunctions were observed. Decreased KE and PF voluntary activation (VA), evoked forces, VL M-wave amplitude, and KE low-frequency fatigue were observed at Post. Changes in VL M-wave amplitude were negatively correlated to VL activity during DTR. Changes in PF twitch force and VA were negatively correlated to GL activity during DTR. The acute KE VA deficit was about a third of that reported after ultramarathons, although peripheral alterations were similar. The prolonged force loss seems to be mainly associated to VA deficit likely induced by the delayed inflammatory response to DTR-induced ultrastructural muscle damage.
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont-Blanc, Le Bourget-du-Lac, France. marlene.giandolini@salomon.com.|Amer Sports Footwear Laboratory of Biomechanics and Exercise Physiology, Salomon SAS, Annecy, France. marlene.giandolini@salomon.com.
authors.forename: M
authors.initials: M
authors.lastname: Giandolini
authors.affiliation: Amer Sports Footwear Laboratory of Biomechanics and Exercise Physiology, Salomon SAS, Annecy, France.
authors.forename: N
authors.initials: N
authors.lastname: Horvais
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont-Blanc, Le Bourget-du-Lac, France.
authors.forename: J
authors.initials: J
authors.lastname: Rossi
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: G Y
authors.initials: GY
authors.lastname: Millet
authors.affiliation: Laboratory of Human Motricity, Education Sport and Health, University of Nice Sophia Antipolis, Nice, France.
authors.forename: J-B
authors.initials: JB
authors.lastname: Morin
authors.affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont-Blanc, Le Bourget-du-Lac, France.
authors.forename: P
authors.initials: P
authors.lastname: Samozino
mesh_terms: D000328:Adult; D004576:Electromyography; D005528:Foot; D006801:Humans; D007717:Knee; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology*; D012420:Running / Q000502:physiology*; D019415:Torque
keywords: Downhill running; central fatigue; muscle activity; peripheral fatigue; trail running