title: Is muscular strength balance influenced by menstrual cycle in female soccer players?
abstract: BACKGROUND
  Muscular strength imbalance is an important risk factor for ACL injury, but it is not clear the impact of menstrual cycle on muscular strength balance. Our aims were to compare muscular balance (hamstring-to-quadriceps peak torque strength balance ratio) between luteal and follicular phases and compare gender differences relative to strength balance to observe possible fluctuations in strength balance ratio.
  
  
  METHODS
  Thirty-eight soccer athletes (26 women and 12 men) took part in this study. Athletes participated in two identical isokinetic strength evaluations for both knee (non-dominant [ND] and dominant [D]). Peak torque for quadriceps and hamstring muscles were measured in concentric mode and hamstring-to-quadriceps peak torque strength balance ratio calculated.
  
  
  RESULTS
  Women had significantly lower hamstring-to-quadriceps peak torque strength balance ratio during the follicular compared to luteal phase, for the ND limb (P=0.011). However, no differences, between luteal and follicular phases, were observed in the D limb. In men, no difference in strength balance ratios was found between the ND and D limbs.
  
  
  CONCLUSIONS
  These data may be useful in prevention programs for knee (ACL) injuries among soccer female athletes.
authors.affiliation: Department of Physiology, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Marília
authors.initials: M
authors.lastname: Dos Santos Andrade
authors.affiliation: Department of Physiology, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Naryana C
authors.initials: NC
authors.lastname: Mascarin
authors.affiliation: Department of Gynecology, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Roberta
authors.initials: R
authors.lastname: Foster
authors.affiliation: Department of Gynecology, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Zsuzsanna I
authors.initials: ZI
authors.lastname: de Jármy di Bella
authors.affiliation: Center of Physical Education and Sports, Federal University of Espírito Santo, Vitória, Brazil.
authors.forename: Rodrigo L
authors.initials: RL
authors.lastname: Vancini
authors.affiliation: Section of Human Physiology and Exercise, Faculty of Physical Education and Dance, Federal University of Goiás, Goiânia, Brazil - andre.claudio@gmail.com.
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Barbosa de Lira
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000070598:Anterior Cruciate Ligament Injuries / Q000517:prevention & control; D005260:Female; D000070633:Hamstring Muscles / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008297:Male; D008597:Menstrual Cycle / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D012737:Sex Factors; D012916:Soccer / Q000502:physiology*; D019415:Torque; D055815:Young Adult