Effects of resistance exercise training on mass, strength, and turnover of bone in growing rats |
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Authors: | Takuya Notomi Sang Jig Lee Nobukazu Okimoto Yuichi Okazaki Takaichi Takamoto Toshitaka Nakamura Masashige Suzuki |
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Affiliation: | (1) Laboratory and Biochemistry of Exercise and Nutrition, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba 305-8574, Japan, JP;(2) Department of Orthopedic Surgery, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan, JP;(3) Institute of Health and Sports Sciences, University of Tsukuba, Tsukuba-shi, Ibaragi-ken, Japan, 305-8574 e-mail: notomi@taiiku.tsukuba.ac.jp Tel.: +81-298-532733; Fax: +81-298-532733, JP |
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Abstract: | To determine the effects of resistance exercise on mass, strength and local turnover of bone, 50 Sprague Dawley rats, 8 weeks of age, were assigned to five groups: a baseline control and two groups of sedentary and exercising rats. The trunk of the rats was kept upright during electrically stimulated jumping exercise for 1 h every other day. In 4 weeks, the trabecular mineralizing surface per bone surface (MS/BS), bone formation rate per bone surface (BFR/BS) and the compression load of the lumbar body increased and the number of osteoclasts decreased, but bone mineral density (BMD) and structure did not increase. In the mid femur, the cross-sectional area, the cortical bone area, the moment of inertia, the periosteal MS/BS, BFR/BS and the bending load increased in the exercise group. In 8 weeks, the increases in BMD, structure and load values were significant in both the lumbar and mid femur. At both 4 and 8 weeks, the MS/BS for the endocortical surface of mid femur were not increased and mineral apposition rate (MAR) remained reduced. These results show that jumping exercise increases the mass and strength of the lumbar vertebrae and mid femur by stimulating bone formation and accelerates cortical drift by both increasing periosteal bone formation and reducing the endocortical MAR. Accepted: 1 February 2000 |
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Keywords: | Bone formation Cortical drift Jumping Trunk upright position Osteoclast |
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