Effects of running on the torsional strength, morphometry, and bone mass of the rat skeleton

Document Type

Article

Publication Date

4-1995

Publication Title

Medicine and Science in Sports and Exercise

Abstract

0.05) on bone \nstrength when compared with control values. Higher intensity exercise \ndecreased tibial and femoral torque (P < 0.05). Long duration \nexercise increased tibial and femoral stiffness and decreased twist \nangle and energy absorbed (P < 0.05). These results indicate bone \nadapts to its loading environment by increasing bone mineral density, \nincreasing cortical bone area, increasing stiffness, decreasing energy \nabsorbed, and decreasing twist angle. High-intensity exercise decreased \nthe maximum force the bone could withstand, whereas long duration \nexercise made the bone more brittle.\n \n\n \n "}" data-sheets-userformat="{"2":771,"3":{"1":0},"4":{"1":2,"2":16777215},"11":4,"12":0}" style="font-size: 10pt; font-family: Arial;">Intensity and duration effects of weight-bearing exercise on the rat skeleton were investigated. Eighty-four 3-month-old female Sprague-Dawley rats were assigned to control and nine exercise groups. Exercised rats were run on a treadmill for either 30, 60, or 90 min.d-1 at low (Vo2max approximately 55%), medium (VO2max approximately 65%), or high (VO2max approximately 75%) intensity 4 d.wk-1 for 10 wk. Rat femurs, tibias, and vertebrae were harvested for torsional mechanical tests, bone density assessment, and morphometry. Our results indicate exercise has a significant effect (P < 0.05) on the femoral mechanical response (energy absorbed and twist angle), tibial morphometry (cortical bone area and thickness), and tibial and vertebral bone density measurements but had no effect (P > 0.05) on bone strength when compared with control values. Higher intensity exercise decreased tibial and femoral torque (P < 0.05). Long duration exercise increased tibial and femoral stiffness and decreased twist angle and energy absorbed (P < 0.05). These results indicate bone adapts to its loading environment by increasing bone mineral density, increasing cortical bone area, increasing stiffness, decreasing energy absorbed, and decreasing twist angle. High-intensity exercise decreased the maximum force the bone could withstand, whereas long duration exercise made the bone more brittle.

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