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Abstract

This experiment was designed to study the effects of intensity of exercise on bone adaptations in ovariectomized and sham operated 12 week old rats. Eighty Sprague Dawley rats were divided by mass into two equal groups (mean = 197 g). One group was ovariectomized (OVX); the other sham (S) operated. Each surgery group was then subdivided by mass into four exercise intensity groups. The exercise intensity groups were created by loading additional mass (percent of animals body mass, 0%, 3%, 6% and 9%) on each animal in combination with treadmill running (10 m/min.; 30 min./day; 4 days/wk.; for 7 weeks). Intensity of exercise and OVX had a significant effect on bone integrity (BI) (P<.001), a construct that consisted if bone breaking strength, apparent bone density and % ash wt. OVX seemed to influence BI more than intensity of exercise. Breaking strength was significantly affected by OVX (P>/001). Upon further analysis, OVX had the most significant effect on any of the construct variables. When the construct variables were compared between groups, bone breaking strength was significantly greater in the OVX than the S (P=.024). There was no effect on bone density between the groups, and ASH% was significantly less in the OVX than the S.

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