title: Effects of treadmill exercise on bone mass, bone metabolism, and calciotropic hormones in young growing rats.
abstract: The aim of the present study was to examine the effects of exercise on bone mass, bone metabolism, and calciotropic hormones in young growing rats. Twenty 6-week-old female Wistar rats were randomized into the following four groups with 5 animals each: 7 weeks of exercise, 7 weeks of sedentary control, 11 weeks of exercise, and 11 weeks of sedentary control. The exercise regimen consisted of running on a treadmill at 25 m/min for 1 h each day on 5 days a week. After each period of exercise, the bone mineral content (BMC) of the tibia and fifth lumbar spine was measured by dual-energy X-ray absorptiometry, using a Lunar DPX-L instrument. The femoral length and levels of bone markers and calciotropic hormones were also assessed. Seven and 11 weeks of exercise increased the serum osteocalcin and 1,25-dihydroxyvitamin D(3) levels, and decreased the serum parathyroid level. Seven weeks of exercise decreased the urinary deoxypyridinoline level, and 11 weeks of exercise increased the serum alkaline phosphatase level and decreased the serum tartrate-resistant acid phosphatase level. As a result, 7 and 11 weeks of exercise increased the femoral length and tibial BMC, but did not alter the lumbar BMC. The present study demonstrates that treadmill exercise stimulates bone formation and suppresses bone resorption, increases the serum 1,25-dihydroxyvitamin D(3) level, and decreases the serum parathyroid hormone level, resulting in an increase in bone mass with stimulation of longitudinal bone growth, especially at weight-bearing sites, in young growing rats. Further studies with long-term exercise may be needed to obtain a positive effect on the lumbar BMC.
authors.affiliation: Department of Sports Medicine, Keio University School of Medicine, Tokyo, Japan. jiwamoto@sc.itc.keio.ac.jp
authors.forename: Jun
authors.initials: J
authors.lastname: Iwamoto
authors.forename: Chisato
authors.initials: C
authors.lastname: Shimamura
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takeda
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Abe
authors.forename: Shoichi
authors.initials: S
authors.lastname: Ichimura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sato
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D015502:Absorptiometry, Photon; D000135:Acid Phosphatase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D000596:Amino Acids / Q000378:metabolism / Q000652:urine; D000818:Animals; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism*; D002117:Calcitriol / Q000097:blood / Q000378:metabolism; D002118:Calcium / Q000097:blood / Q000378:metabolism; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000737:chemistry; D006728:Hormones / Q000378:metabolism*; D007527:Isoenzymes / Q000097:blood; D008159:Lumbar Vertebrae / Q000737:chemistry; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D015675:Osteocalcin / Q000097:blood / Q000378:metabolism; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism; D010758:Phosphorus / Q000097:blood / Q000378:metabolism; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D000071681:Tartrate-Resistant Acid Phosphatase; D013977:Tibia / Q000737:chemistry
chemical_list: D000596:Amino Acids; D006728:Hormones; D007527:Isoenzymes; D010281:Parathyroid Hormone; D015675:Osteocalcin; D010758:Phosphorus; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002117:Calcitriol; D002118:Calcium