Running exercise for short duration increases bone mineral density of loaded long bones in young growing rats.
Running exercise is an effective therapy for the prevention of osteoporosis; however, appropriate duration of exercise has not been determined. We therefore investigated the effect of exercise duration on bone mineral density (BMD) and systemic bone metabolism using young growing rats. Fifteen 8-week-old female Wistar rats were divided into three groups according to running load: control group (no running), short duration (30 min/day) and long duration (180 min/day), and animals ran on a treadmill 5 days per week over an 8-week period. BMD of the tibia was measured using peripheral quantitative computed tomography, and serum levels of tartarate-resistant acid phosphatase (TRAP), a bone resorption marker and alkaline phosphatase (ALP), a bone formation marker were measured to know whether the treadmill exercise would affect systemic bone metabolism. Short-duration running exercise (30 min/day) caused a significant increase in BMD of the metaphyseal trabecula (p < 0.05) with a reduction of serum TRAP levels (p < 0.01) and an increase in serum levels of calcium (p < 0.05) and phosphorus (p < 0.01). Conversely, long-duration exercise (180 min/day) significantly reduced BMD of the diaphyseal and metaphyseal cortex and that of the diaphyseal trabecula with a significant reduction of serum ALP levels and a significant increase in serum phosphorus. These findings suggest that short-duration exercise may increase BMD through suppression of bone resorption, whereas long-duration exercise may reduce BMD through suppression of bone formation. Exercising for short duration but not prolonged exercise is recommended to increase BMD of loaded long bones.
Hagihara
Yoshinobu
Y
Department of Orthopaedic Surgery, Chiba University Graduate School of Medicine, Chiba, Japan.
Nakajima
Arata
A
Fukuda
Satoshi
S
Goto
Sumio
S
Iida
Haruzo
H
Yamazaki
Masashi
M
D000135:Acid Phosphatase / Q000097:blood; D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002118:Calcium / Q000097:blood; D005260:Female; D007527:Isoenzymes / Q000097:blood; D010758:Phosphorus / Q000097:blood; D010805:Physical Conditioning, Animal; D051381:Rats; D017208:Rats, Wistar; D000071681:Tartrate-Resistant Acid Phosphatase; D013977:Tibia / Q000254:growth & development* / Q000502:physiology*; D013997:Time Factors; D015430:Weight Gain / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*
D007527:Isoenzymes; D010758:Phosphorus; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002118:Calcium