title: Gait-cycle characteristics and running economy in elite Eritrean and European runners.
abstract: OBJECTIVE
  This study aimed to determine whether biomechanical characteristics such as ground-contact time, swing time, and stride length and frequency contribute to the exceptional running economy of East African runners.
  
  
  METHODS
  Seventeen elite long-distance runners (9 Eritrean, 8 European) performed an incremental maximal running test and 3 submaximal running bouts at 17, 19, and 21 km/h. During the tests, gas-exchange parameters were measured to determine maximal oxygen uptake (VO2max) and running economy (RE). In addition, ground-contact time, swing time, stride length, and stride frequency were measured.
  
  
  RESULTS
  The European runners had higher VO2max values than the Eritrean runners (77.2 ± 5.2 vs 73.5 ± 6.0 mL · kg-1 · min-1, P = .011, effect sizes [ES] = 0.65), although Eritrean runners were more economical at 19 km/h (191.4 ± 10.4 vs 205.9 ± 13.3 mL · kg-1 · min-1, P = .026, ES = 1.21). There were no differences between groups for ground-contact time, swing time, stride length, or stride frequency at any speed. Swing time was associated with running economy at 21 km/h in the Eritrean runners (r = .71, P = .033), but no other significant association was found between RE and biomechanical variables. Finally, best 10-km performance was significantly correlated with RE (r = -.57; P = .013).
  
  
  CONCLUSIONS
  Eritrean runners have superior RE compared with elite European runners. This appears to offset their inferior VO2max. However, the current data suggest that their better RE does not have a biomechanical basis. Other factors, not measured in the current study, may contribute to this RE advantage.
authors.affiliation: Dept of Human Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: Jordan
authors.initials: J
authors.lastname: Santos-Concejero
authors.forename: Jesús
authors.initials: J
authors.lastname: Oliván
authors.forename: José L
authors.initials: JL
authors.lastname: Maté-Muñoz
authors.forename: Carlos
authors.initials: C
authors.lastname: Muniesa
authors.forename: Marta
authors.initials: M
authors.lastname: Montil
authors.forename: Ross
authors.initials: R
authors.lastname: Tucker
authors.forename: Alejandro
authors.initials: A
authors.lastname: Lucia
mesh_terms: D000328:Adult; D000351:Africa, Eastern / Q000208:ethnology; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D005684:Gait / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000033:anatomy & histology; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012420:Running / Q000502:physiology*; D013030:Spain / Q000208:ethnology; D055815:Young Adult