Five jumps per day increase bone mass and breaking force in rats

J Bone Miner Res. 1997 Sep;12(9):1480-5. doi: 10.1359/jbmr.1997.12.9.1480.


The effects of jump training on bone morphological and mechanical properties were investigated in immature bones of female Fischer 344 rats. Five-week-old rats were divided into control or five jump-trained groups comprised of 5-, 10-, 20-, 40-, and 100-jump groups, representing the number of jumps per day. The rats were jump-trained 5 days/week for 8 weeks, and the height of jump was increased to 40 cm progressively. The femur and tibia in the 5-jump group had significantly greater fat-free dry weights per body weight and maximum loads at the fracture tests than those in the control group. The tibia in the 5-jump group also had significantly larger cortical area at the cross-sectional analysis. Although a slight tendency toward increase according to the number of jumps per day was observed, there were few differences in bone morphological and mechanical parameters among the 10-, 20-, and 40-jump groups. The present results indicate that a large number of strains per day is not necessary for bone hypertrophy to develop in rats.

MeSH terms

  • Animals
  • Bone Density*
  • Female
  • Femur / anatomy & histology
  • Hyperostosis / etiology*
  • Hyperostosis / pathology
  • Physical Conditioning, Animal / physiology*
  • Rats
  • Rats, Inbred F344
  • Stress, Mechanical
  • Tibia / anatomy & histology