title: Menstrual cycle and knee joint position sense in healthy female athletes.
abstract: OBJECTIVE
  The aim of this study was to investigate the effect of menstrual cycle on knee joint position sense (JPS) in healthy female athletes.
  
  
  METHODS
  Sixteen healthy female athletes participated in this study. Serum estrogen and progesterone levels were collected during the three phases of menstrual cycle. The knee JPS was also measured during the same phases using a system comprise of skin markers, digital photography, and AutoCAD software. Absolute angular errors were calculated as well as changes in hormone levels between the three phases.
  
  
  RESULTS
  Serum estrogen concentration was significantly higher during the mid-luteal (179.5 Pg/ml) and mid-follicular (125.6 Pg/ml) phases as compared with the early-follicular (menses) (22.8 Pg/ml) phase (P = 0.0001). Also serum progesterone concentration was significantly higher during the mid-luteal phase (7.35 Ng/ml) as compared with the menses (0.58 Ng/ml) and mid-follicular (0.5 Ng/ml) phases (P = 0.0001). The greatest amount of mean (SD) value of absolute error was at menses (4.2°), and the least amount of it was at mid-luteal (2.5°) phase. Also, a significant difference was observed within three phases of menstrual cycle (P = 0.025).
  
  
  CONCLUSIONS
  The result of this study suggests that healthy female athletes have different levels of knee JPS across a menstrual cycle. JPS accuracy decreases in menses, when circulating sex-hormones levels are low. Therefore, female athletes are at higher risk of injury at menses and improving their awareness regarding the knee injury risk factors can be a fundamental step toward preventing injuries.
  
  
  METHODS
  Case series, Level IV.
authors.affiliation: Sports Science and Physical Education Department, Tehran University, Tehran, Iran.
authors.forename: Rose
authors.initials: R
authors.lastname: Fouladi
authors.forename: Reza
authors.initials: R
authors.lastname: Rajabi
authors.forename: Nasrin
authors.initials: N
authors.lastname: Naseri
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Pourkazemi
authors.forename: Mehrnaz
authors.initials: M
authors.lastname: Geranmayeh
mesh_terms: D000328:Adult; D056352:Athletes; D004967:Estrogens / Q000097:blood*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008597:Menstrual Cycle / Q000097:blood / Q000502:physiology*; D011374:Progesterone / Q000097:blood*; D011434:Proprioception / Q000502:physiology*; D055815:Young Adult
chemical_list: D004967:Estrogens; D011374:Progesterone