title: Tennis in hot and cool conditions decreases the rapid muscle torque production capacity of the knee extensors but not of the plantar flexors.
abstract: OBJECTIVE
  To assess the time course of changes in rapid muscle force/torque production capacity and neuromuscular activity of lower limb muscles in response to prolonged (∼2 h) match-play tennis under heat stress.
  
  
  METHODS
  The rates of torque development (RTD) and electromyographic activity (EMG; ie, root mean square) rise were recorded from 0 to 30, -50, -100 and -200 ms during brief (3-5 s) explosive maximal isometric voluntary contractions (MVC) of the knee extensors (KE) and plantar flexors (PF), along with the peak RTD within the entirety of the torque-time curve. These values were recorded in 12 male tennis players before (prematch) and after (postmatch, 24 and 48 h) match-play in HOT (∼37°C) and COOL (∼22°C) conditions.
  
  
  RESULTS
  The postmatch core temperature was greater in the HOT (∼39.4°C) vs COOL (∼38.7°C) condition (p<0.05). Reductions in KE RTD occurred within the 0-200 ms epoch after contraction onset postmatch and at 24 h, compared with prematch, independent of environmental conditions (p<0.05). A similar reduction in the KE peak RTD was also observed postmatch relative to prematch (p<0.05). No differences in KE RTD values were observed after normalisation to MVC torque. Furthermore, the rate of KE EMG activity rise remained unchanged. Conversely, the PF contractile RTD and rate of EMG activity rise were unaffected by the exercise or environmental conditions.
  
  
  CONCLUSIONS
  In the KE, a reduction in maximal torque production capacity following prolonged match-play tennis appears to account for the decrease in the rate of torque development, independent of environmental conditions, while remaining unchanged in the PF.
authors.affiliation: Aspetar-Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, , Doha, Qatar.
authors.forename: Olivier
authors.initials: O
authors.lastname: Girard
authors.forename: Sébastien
authors.initials: S
authors.lastname: Racinais
authors.forename: Julien D
authors.initials: JD
authors.lastname: Périard
mesh_terms: D001833:Body Temperature Regulation / Q000502:physiology; D003080:Cold Temperature; D004576:Electromyography; D006358:Hot Temperature; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D013715:Tennis / Q000502:physiology*; D019415:Torque; D055815:Young Adult
keywords: Adaptations of skeletal muscle to exercise and altered neuromuscular activity; Exercise; Exercise physiology; Fatigue; Thermoregulation