title: Neuromuscular adjustments of the knee extensors and plantar flexors following match-play tennis in the heat.
abstract: OBJECTIVE
  This study tested the hypothesis that impairments in lower limb maximal strength and voluntary activation (VA) are exacerbated following match-play tennis in hot compared with cool conditions.
  
  
  METHODS
  Torque and VA were evaluated during brief (5 s) and sustained (20 s) maximal voluntary isometric contractions of the knee extensors (KE) and plantar flexors (PF) in 12 male tennis players before (pre) and after (post, 24 h and 48 h) ∼115 min of play in hot (∼37°C) and cool (∼22°C) conditions.
  
  
  RESULTS
  Rectal temperature was higher following play in hot than in cool (∼39.2 vs ∼38.5°C; p<0.05). Torque production decreased from prematch to postmatch during the brief and sustained contractions in hot (KE: ∼22%; PF: ∼13%) and cool (KE: ∼9%, PF: ∼7%) (p<0.05). KE strength losses in hot were greater than in cool (p<0.05) and persisted for 24 h (p<0.05). Postmatch brief and sustained KE VA was lower in hot than in cool (p<0.05), in which VA was maintained. PF VA was maintained throughout the protocol. Peak twitch torque and maximum rates of torque development and relaxation in the KE and PF were equally reduced postmatch relative to prematch in hot and cool conditions (p<0.05), and were restored near baseline within 24 h.
  
  
  CONCLUSIONS
  Neuromuscular system integrity of the lower limbs is compromised immediately following match-play tennis in hot and cool conditions due to the development of peripheral fatigue. The larger and persistent KE strength losses observed under heat stress are associated with greater levels of central fatigue especially during sustained contractions.
authors.affiliation: Athlete Health and Performance Research Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, , Doha, Qatar.
authors.forename: Julien D
authors.initials: JD
authors.lastname: Périard
authors.forename: Olivier
authors.initials: O
authors.lastname: Girard
authors.forename: Sébastien
authors.initials: S
authors.lastname: Racinais
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000294:innervation / Q000502:physiology*; D007866:Leg / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D013715:Tennis / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: Fatigue; Strength isometric isokinetic; Thermoregulation