Kazuhiro Onaru    Department   Kawasaki Medical School  Kawasaki Medical School, Department of Bone and Joint Surgery,    Position   Assistant Professor
Language	English
Title	Exercise and Trabecular Bone Architecture After Hindlimb Unloading
Conference	The 25th International Sport Science Congress of KAPERD
Conference Type	International society and overseas society
Invitation	Invitation
Presentation Type	Speech
Lecture Type	Special/Invited Lecture
Publisher and common publisher	◎Ju Yong-In, Sone Teruki, Choi Hak-Jin, Ohnaru Kazuhiro, Choi Kyung-A, Fukunaga Masao
Date	2013/08/22
Venue (city and name of the country)	Yong-In, South Korea
Society abstract	In Pursuit of Evidence-Based Sport and Exercise Science 212 2013
Summary	Mechanical stress is regarded as an important determinant of the structural and functional integrity of the skeletal system in humans and other animals. Skeletal unloading causes rapid and marked bone loss, as has been demonstrated in humans following spaceflight or prolonged bed rest, and has been extensively modeled in animals. Previous studies of skeletal reloading after prolonged skeletal unloading have indicated incomplete recovery of bone mass and architectural parameters, even after recovery periods longer than the duration of unloading. We investigated the ability of jump exercise to restore bone mass and structure after the deterioration induced by tail-suspension in growing rats, and made comparisons with treadmill running exercise. After removal from the tail suspension apparatus, rats were forced to jump and treadmill running exercise. The jump exercise program comprised 10 jumps/day, 5 days/week for 5 weeks. Treadmill running was performed at 25 m/min, 1 h/day, 5 days/week for 5 weeks. Bone mineral density (BMD) of the total right femur was measured by dual-energy X-ray absorptiometry. Three-dimensional (3D) trabecular bone architecture at the distal femoral metaphysis was evaluated using microcomputed tomography. The major finding in this study was that suspension-induced trabecular deterioration persists after remobilization and that jump and running exercises during the remobilization period can restore the integrity of the femoral trabecular architecture in young growing rats. However, the effects on cancellous bone mass differed between jump and running exercises in that jump exercise increased trabecular bone volume by thickening existing trabeculae, whereas treadmill running exercise added bone by creating new trabeculae and increasing trabecular connectivity. These results suggest that jump and running exercises have different mechanisms of action on structural characteristics of trabecular bone.