title: Effects of high-intensity swimming training on the bones of ovariectomized rats.
abstract: OBJECTIVE
  This study was performed to assess the effects of high-intensity intermittent swimming training(HIT) on bone in ovariectomized rats.
  
  
  METHODS
  Six-week-old female Sprague-Dawley rats were randomly assigned to either sham operation or bilateral ovariectomy. After surgery, they were divided into the following four groups: 1) sham-operated sedentary (S), 2) sham-operated exercise training (SE), 3) OVX sedentary (O), 4) OVX exercise training (OE) 5) OVX given 17β-estradiol (OE2) and 6) OVX exercise training and given 17β-estradiol (OEE). SE, OE and OEE rats were used extremely high-intensity swim exercise. The rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 5, the next 9, and the last 5 days, respectively. Between exercise bouts, a 10-s pause was allowed. HIT was originally designed as an exercise method; a method that very quickly induces an increase in the maximum oxygen intake (Tabata I et al., 1996). OEE and OE2 rats were subcutaneously injected ethanol with 25μg/kg body weight 17β-estradiol 3 times per week.
  
  
  RESULTS
  Bone strength, bone mineral density and trabecular bone parameters were measured after a 8-weeks experimental period. Bone strength was significantly higher in the SE, OE, OE2 and OEE group compared with the O group. BV/TV was significant increase in the SE, OE groups compared with the O group. BMD showed no difference in the OE group compared with the O group.
  
  
  CONCLUSIONS
  This study demonstrate some beneficial effects of postmenopausal osteoporosis of high-intensity intermittent swimming training on bone structure and strength.
authors.affiliation: Dean of the College of Sports Sciences, Yongin University, Yongin-Si Republic of Korea.
authors.forename: Taewoong
authors.initials: T
authors.lastname: Oh
authors.affiliation: Graduate School of Health Science, Matsumoto University, Nagano Japan.
authors.forename: Sakura
authors.initials: S
authors.lastname: Tanaka
authors.affiliation: Faculty of Wellness, Shigakkan University, Aichi Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Naka
authors.affiliation: Graduate School of Health Science, Matsumoto University, Nagano Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Igawa
keywords: Bone; High-intensity exercise; Ovariectomized rat; Swimming training