title: High-intensity running and plantar-flexor fatigability and plantar-pressure distribution in adolescent runners.
abstract: BACKGROUND
  Fatigue-induced alterations in foot mechanics may lead to structural overload and injury.
  
  
  OBJECTIVE
  To investigate how a high-intensity running exercise to exhaustion modifies ankle plantar-flexor and dorsiflexor strength and fatigability, as well as plantar-pressure distribution in adolescent runners.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Academy research laboratory.
  
  
  METHODS
  Eleven male adolescent distance runners (age = 16.9 ± 2.0 years, height = 170.6 ± 10.9 cm, mass = 54.6 ± 8.6 kg) were tested.
  
  
  METHODS
  All participants performed an exhausting run on a treadmill. An isokinetic plantar-flexor and dorsiflexor maximal-strength test and a fatigue test were performed before and after the exhausting run. Plantar-pressure distribution was assessed at the beginning and end of the exhausting run.
  
  
  METHODS
  We recorded plantar-flexor and dorsiflexor peak torques and calculated the fatigue index. Plantar-pressure measurements were recorded 1 minute after the start of the run and before exhaustion. Plantar variables (ie, mean area, contact time, mean pressure, relative load) were determined for 9 selected regions.
  
  
  RESULTS
  Isokinetic peak torques were similar before and after the run in both muscle groups, whereas the fatigue index increased in plantar flexion (28.1%; P = .01) but not in dorsiflexion. For the whole foot, mean pressure decreased from 1 minute to the end (-3.4%; P = .003); however, mean area (9.5%; P = .005) and relative load (7.2%; P = .009) increased under the medial midfoot, and contact time increased under the central forefoot (8.3%; P = .01) and the lesser toes (8.9%; P = .008).
  
  
  CONCLUSIONS
  Fatigue resistance in the plantar flexors declined after a high-intensity running bout performed by adolescent male distance runners. This phenomenon was associated with increased loading under the medial arch in the fatigued state but without any excessive pronation.
authors.affiliation: Aspire Health Centre, National Sports Medicine Programme (NSMP), Doha, Qatar;
authors.forename: François
authors.initials: F
authors.lastname: Fourchet
authors.forename: Luke
authors.initials: L
authors.lastname: Kelly
authors.forename: Cosmin
authors.initials: C
authors.lastname: Horobeanu
authors.forename: Heiko
authors.initials: H
authors.lastname: Loepelt
authors.forename: Redha
authors.initials: R
authors.lastname: Taiar
authors.forename: Grégoire
authors.initials: G
authors.lastname: Millet
mesh_terms: D000293:Adolescent; D016512:Ankle Injuries / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D000843:Ankle Joint / Q000502:physiology / Q000503:physiopathology; D001265:Athletic Injuries / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D005080:Exercise Test / Q000379:methods; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D011312:Pressure; D011403:Pronation; D012420:Running / Q000502:physiology*; D013180:Sprains and Strains / Q000503:physiopathology; D019415:Torque
keywords: ankle; isokinetic exercise; medial longitudinal arch; pronation