title: Effects of Footwear and Fatigue on Running Economy and Biomechanics in Trail Runners.
abstract: This study aimed to examine the effects of footwear and neuromuscular fatigue induced by short distance trail running (TR) on running economy (RE) and biomechanics in well-trained and traditionally shod runners.
  
  
  
  RE, vertical and leg stiffness (Kvert and Kleg), as well as foot strike angle were measured from two 5-min treadmill running stages performed at a speed of 2.5 (with 10% grade, uphill running) and 2.77 m·s (level running) before and after an 18.4-km TR exercise (approximately 90% of maximal heart rate) in runners wearing minimalist shoes (MS), MS plus added mass (MSm), or traditional shoes (TS). Maximal voluntary contraction torque of knee extensors and perceived muscle pain were also evaluated before and after TR.
  
  
  
  Maximal voluntary contraction values decreased after TR in all footwear conditions (P < 0.001), indicating the occurrence of neuromuscular fatigue. In the nonfatigued condition, runners exhibited a better RE only during level running in MS and MSm (i.e., combined effects of shoe mass and midsole geometry), in association with significant decreases in foot strike angle (P < 0.05). However, no significant difference in RE was observed between shod conditions after TR during either uphill or level running. Decreases in both Kvert/Kleg and foot strike angle were more pronounced during running in MS and MSm (P < 0.05) compared with TS, whatever the period. Calf pain increased after TR when wearing MS and MSm compared with TS (P < 0.05).
  
  
  
  These findings indicated specific alterations in RE and biomechanics over time during the MS and MSm conditions compared with the TS condition. Future studies are warranted to evaluate the relationship between RE and footwear with fatigue in experienced minimally shod runners.
authors.affiliation: 1Laboratoire Motricité Humaine Expertise Sport Santé (LAMHESS), Université de Nice Sophia Antipolis/Université de Toulon, Toulon, FRANCE; 2LABIER, Midwest State University of Paraná, Guarapuava, BRAZIL; 3SALOMON SAS, Amer Sports Footwear Laboratory of Biomechanics and Exercise Physiology, Annecy, FRANCE; 4Laboratory of Exercise Physiology, University Savoie Mont Blanc, Le Bourget-du-Lac, FRANCE; and 5School of Exercise Science, Murdoch University, Perth, AUSTRALIA.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Vercruyssen
authors.forename: Marcus
authors.initials: M
authors.lastname: Tartaruga
authors.forename: Nicolas
authors.initials: N
authors.lastname: Horvais
authors.forename: Jeanick
authors.initials: J
authors.lastname: Brisswalter
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D007866:Leg / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D063806:Myalgia / Q000503:physiopathology; D012420:Running / Q000502:physiology*; D012775:Shoes