Effects of treadmill exercise on bone mass, bone metabolism, and calciotropic hormones in young growing rats.
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.
Iwamoto
Jun
J
Department of Sports Medicine, Keio University School of Medicine, Tokyo, Japan. jiwamoto@sc.itc.keio.ac.jp
Shimamura
Chisato
C
Takeda
Tsuyoshi
T
Abe
Hitoshi
H
Ichimura
Shoichi
S
Sato
Yoshihiro
Y
Toyama
Yoshiaki
Y
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
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