title: A gender comparison of central and peripheral neuromuscular function after exercise.
abstract: BACKGROUND
  Central and peripheral muscle fatigue during exercise may exacerbate neuromuscular factors that increase risk for noncontact anterior cruciate ligament injury.
  
  
  OBJECTIVE
  To compare lower extremity motor-evoked potentials (MEPs), muscle strength, and electromyography (EMG) activation after an exercise protocol.
  
  
  METHODS
  Pretest, posttest group comparison.
  
  
  METHODS
  University laboratory.
  
  
  METHODS
  34 healthy volunteers (17 female, age = 21.9 ± 2.3 years, weight = 77.8 ± 3.0 kg, height = 171.1 ± 6.6 cm, and 17 male, age = 23.4 ± 6.5 years, weight = 81.6 ± 3.3 kg, height = 179.6 ± 7.3 cm).
  
  
  METHODS
  A standardized 30-min exercise protocol that involved 5 repeated cycles of uphill walking, body-weight squatting, and step-ups.
  
  
  METHODS
  Quadriceps and hamstring MEP amplitude (mV) and transmission velocity normalized to subject height (m/s) were elicited via transcranial magnetic stimulation and measured via surface EMG. Quadriceps and hamstring peak EMG activation (% MVIC) and peak torque (Nm/kg) were measured during MVICs. Separate ANCOVAs were used to compare groups after exercise while controlling for baseline measurement.
  
  
  RESULTS
  At baseline, males exhibited significantly greater knee-extension torques (males = 2.47 ± 0.68 Nm/kg, females = 1.95 ± 0.53 Nm/kg; P = .036) and significantly higher hamstring MEP amplitudes (males = 223.5 ± 134.0 mV, females = 89.3 ± 77.6 mV; P = .007). Males exhibited greater quadriceps MEP amplitude after exercise than females (males = 127.2 ± 112.7 mV, females = 32.3 ± 34.9 mV; P = .016).
  
  
  CONCLUSIONS
  Males experienced greater peripheral neuromuscular changes manifested as more pronounced reductions in quadriceps torque after exercise. Females experienced greater central neuromuscular changes manifested as more pronounced reduction in quadriceps MEP amplitude. Reduced central neural drive of the quadriceps coupled with knee-extension torque preservation after exercise may increase risk of knee injury in females.
authors.affiliation: Dept of Human Services, University of Virginia, Charlottesville, VA, USA.
authors.forename: Ashley
authors.initials: A
authors.lastname: Stern
authors.forename: Chris
authors.initials: C
authors.lastname: Kuenze
authors.forename: Daniel
authors.initials: D
authors.lastname: Herman
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Sauer
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Hart
mesh_terms: D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005783:Gender Identity; D006801:Humans; D007718:Knee Injuries / Q000209:etiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011795:Surveys and Questionnaires; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult