title: Effects of an Uphill Marathon on Running Mechanics and Lower-Limb Muscle Fatigue.
abstract: OBJECTIVE
  To investigate the effects of an uphill marathon (43 km, 3063-m elevation gain) on running mechanics and neuromuscular fatigue in lower-limb muscles.
  
  
  METHODS
  Maximal mechanical power of lower limbs (MMP), temporal tensiomyographic (TMG) parameters, and muscle-belly displacement (Dm) were determined in the vastus lateralis muscle before and after the competition in 18 runners (age 42.8 ± 9.9 y, body mass 70.1 ± 7.3 kg, maximal oxygen uptake 55.5 ± 7.5 mL · kg-1 · min-1). Contact (tc) and aerial (ta) times, step frequency (f), and running velocity (v) were measured at 3, 14, and 30 km and after the finish line (POST). Peak vertical ground-reaction force (Fmax), vertical displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (kvert) and leg (kleg) stiffness were calculated.
  
  
  RESULTS
  MMP was inversely related with race time (r = -.56, P = .016), tc (r = -.61, P = .008), and Δz (r = -.57, P = .012) and directly related with Fmax (r = .59, P = .010), ta (r = .48, P = .040), and kvert (r = .51, P = .027). In the fastest subgroup (n = 9) the following parameters were lower in POST (P < .05) than at km 3: ta (-14.1% ± 17.8%), Fmax (-6.2% ± 6.4%), kvert (-17.5% ± 17.2%), and kleg (-11.4% ± 10.9%). The slowest subgroup (n = 9) showed changes (P < .05) at km 30 and POST in Fmax (-5.5% ± 4.9% and -5.3% ± 4.1%), ta (-20.5% ± 16.2% and -21.5% ± 14.4%), tc (5.5% ± 7.5% and 3.2% ± 5.2%), kvert (-14.0% ± 12.8% and -11.8% ± 10.0%), and kleg (-8.9% ± 11.5% and -11.9% ± 12%). TMG temporal parameters decreased in all runners (-27.35% ± 18.0%, P < .001), while Dm increased (24.0% ± 35.0%, P = .005), showing lower-limb stiffness and higher muscle sensibility to the electrical stimulus.
  
  
  CONCLUSIONS
  Greater MMP was related with smaller changes in running mechanics induced by fatigue. Thus, lower-limb power training could improve running performance in uphill marathons.
authors.affiliation: Dept of Biomedical Sciences and Technology, University of Udine, Udine, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Giovanelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Taboga
authors.forename: Enrico
authors.initials: E
authors.lastname: Rejc
authors.forename: Bostjan
authors.initials: B
authors.lastname: Simunic
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Antonutto
authors.forename: Stefano
authors.initials: S
authors.lastname: Lazzer
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D009213:Myography / Q000379:methods; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult