title: Discontinuation of leisure time impact-loading exercise is related to reduction of a calcaneus quantitative ultrasound parameter in young adult Japanese females: a 3-year follow-up study.
abstract: A 3-year follow-up study on 334 young Japanese females enrolled in a university at the age of 18 years revealed that discontinuation of leisure time impact-loading exercises performed in junior high and/or high school was associated with increased risk of reduction in calcaneus osteo-sono assessment index (OSI).
  
  
  BACKGROUND
  Bone strength rapidly increases during puberty and reaches its peak by the end of adolescence. The aim of this study was to determine the lifestyle factors that influence the maintenance of calcaneus OSI in young adult females around the time when peak bone mass is attained.
  
  
  METHODS
  Annual health checkups including OSI measurements, anthropometrics, lifestyle analysis, and blood examination were performed 4 times on 334 Japanese females enrolled in a university at the age of 18 years. According to the slope of OSI change during the 3-year follow-up, the subjects were grouped into two categories: OSI loss (the lowest tertile) and OSI gain/stable (the second and third tertiles).
  
  
  RESULTS
  At the baseline assessment, the OSI loss group had higher OSI and height and an earlier menarche age than the OSI gain/stable group. Performing leisure time impact-loading exercise in junior high and/or high school but discontinuing it at university was associated with increased risk of OSI loss, independent of OSI, height and weight at the age of 18 years, weight change during follow-up, age of menarche, energy-adjusted nutrient intake, and alcohol drinking; the odds ratios were 4.1-4.9 compared with those performing impact-loading exercise at university. In particular, duration, frequency, and subjective intensity of impact-loading exercise during high school were positively associated with OSI loss.
  
  
  CONCLUSIONS
  Discontinuation of leisure time impact-loading exercises performed during late adolescence is associated with an increased risk of OSI loss in young adult females during the 3-year follow-up period.
authors.affiliation: Graduate School of Health and Nutrition Sciences, Nakamura Gakuen University, 5-7-1, Befu, Jounan-ku, Fukuoka, 814-0198, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Nakazono
authors.forename: H
authors.initials: H
authors.lastname: Miyazaki
authors.forename: S
authors.initials: S
authors.lastname: Abe
authors.forename: K
authors.initials: K
authors.lastname: Imai
authors.forename: T
authors.initials: T
authors.lastname: Masuda
authors.forename: M
authors.initials: M
authors.lastname: Iwamoto
authors.forename: R
authors.initials: R
authors.lastname: Moriguchi
authors.forename: H
authors.initials: H
authors.lastname: Ueno
authors.forename: M
authors.initials: M
authors.lastname: Ono
authors.forename: K
authors.initials: K
authors.lastname: Yazumi
authors.forename: K
authors.initials: K
authors.lastname: Moriyama
authors.forename: S
authors.initials: S
authors.lastname: Nakano
authors.forename: H
authors.initials: H
authors.lastname: Tsuda
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology; D000886:Anthropometry / Q000379:methods; D015519:Bone Density / Q000502:physiology*; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000502:physiology*; D004032:Diet / Q000706:statistics & numerical data; D004522:Educational Status; D015444:Exercise / Q000502:physiology*; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007899:Leisure Activities; D008019:Life Style; D009043:Motor Activity / Q000502:physiology; D014463:Ultrasonography; D055815:Young Adult