title: An Ironman triathlon reduces neuromuscular performance due to impaired force transmission and reduced leg stiffness.
abstract: OBJECTIVE
  An Ironman triathlon is associated with changes in body composition as well as decreases in neuromuscular function. While the changes in body composition occurring during an Ironman are well investigated, comprehensive data on the changes in neuromuscular performance are scarce. In the present study, we investigated the mechanical alterations underlying reported reductions in maximal muscular force and power after an Ironman race in men.
  
  
  METHODS
  Before and directly after an Ironman, countermovement jump (CMJ), squat jump (SJ), and multiple one-legged hopping (m1LH) maneuvers were performed to assess fatigue-related alterations in mechanical variables in thirteen male non-professional triathletes.
  
  
  RESULTS
  During CMJ, peak power (P = 0.003), peak velocity (P < 0.001), jump height (P = 0.007), and rate of force development (P = 0.042) decreased during the Ironman. Total (P < 0.001) and positive (P = 0.003) impulses during a CMJ were reduced after the triathlon, while both negative impulses did not differ pre to post Ironman. Absolute peak force remained constant during CMJ (P = 0.200) and SJ (P = 0.764). Maximal voluntary ground reaction force (F m1LH, P < 0.001) and peak stiffness (P = 0.003) during m1LH were decreased after the Ironman.
  
  
  CONCLUSIONS
  The reduced CMJ height was a result of the lower positive impulse. Therefore, the neuromuscular deficit after the Ironman race was due to impairments in force transmission, resulting in a lower average positive force during CMJ, because of a slower rate of force development. The decreased F m1LH could be partly explained by reduced leg stiffness.
authors.affiliation: Exercise Physiology Lab, Institute of Human Movement Sciences, ETH Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
authors.forename: Sandro Manuel
authors.initials: SM
authors.lastname: Mueller
authors.forename: Patrizia
authors.initials: P
authors.lastname: Knechtle
authors.forename: Beat
authors.initials: B
authors.lastname: Knechtle
authors.forename: Marco
authors.initials: M
authors.lastname: Toigo
mesh_terms: D000328:Adult; D054874:Athletic Performance; D015444:Exercise; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*