title: The effect of heating and cooling on time course of voluntary and electrically induced muscle force variation.
abstract: The aim of this study was to investigate the effect of heating and cooling on time course of voluntary and electrically induced muscle force variation.
  
  
  METHODS
  Ten volunteers performed 50 maximal voluntary and electrically induced contractions of the knee extensors at an angle of 120 degrees under the control conditions and after passive lower body heating and cooling in the control, heating, and cooling experiments. Peak torque, torque variation, and half-relaxation time were assessed during the exercise.
  
  
  RESULTS
  Passive lower body heating increased muscle and core temperatures, while cooling lowered muscle temperature, but did not affect core temperature. We observed significantly lower muscle fatigue during voluntary contraction compared with electrically induced contractions. Body heating (opposite to cooling) increased involuntarily induced muscle force, but caused greater electrically induced muscle fatigue. In the middle of the exercise, the coefficient of correlation for electrically induced muscle torque decreased significantly as compared with the beginning of the exercise, while during maximal voluntary contractions, this relation for torque remained significant until the end of the exercise.
  
  
  CONCLUSIONS
  It was shown that time course of voluntary contraction was more stable than in electrically induced contractions.
authors.affiliation: Department of Applied Physiology and Physiotherapy, Lithuanian Academy of Physical Education, Sporto 6, 44221 Kaunas, Lithuania. marius_brazaitis@yahoo.com
authors.forename: Marius
authors.initials: M
authors.lastname: Brazaitis
authors.forename: Albertas
authors.initials: A
authors.lastname: Skurvydas
authors.forename: Kazys
authors.initials: K
authors.lastname: Vadopalas
authors.forename: Laura
authors.initials: L
authors.lastname: Daniusevičiūtė
authors.forename: Zibuoklė
authors.initials: Z
authors.lastname: Senikienė
mesh_terms: D001833:Body Temperature Regulation; D003080:Cold Temperature; D004558:Electric Stimulation; D006361:Heating; D006801:Humans; D007717:Knee / Q000502:physiology; D008297:Male; D009119:Muscle Contraction; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque; D055815:Young Adult