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Titolo:
Bone-loading response varies with strain magnitude and cycle number
Autore:
Cullen, DM; Smith, RT; Akhter, MP;
Indirizzi:
Creighton Univ, Osteoporosis Res Ctr, Omaha, NE 68131 USA Creighton Univ Omaha NE USA 68131 teoporosis Res Ctr, Omaha, NE 68131 USA N Carolina Wesleyan Univ, Rocky Mount, NC 27804 USA N Carolina Wesleyan Univ Rocky Mount NC USA 27804 cky Mount, NC 27804 USA
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 5, volume: 91, anno: 2001,
pagine: 1971 - 1976
SICI:
8750-7587(2001)91:5<1971:BRVWSM>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
MINERAL DENSITY; POSTMENOPAUSAL WOMEN; PHYSICAL-ACTIVITY; LUMBAR SPINE; TIME-COURSE; RAT TIBIA; EXERCISE; MASS; METAANALYSIS; INCREASES;
Keywords:
tibia; adult rat; strain; histology; mechanical loading;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Cullen, DM Creighton Univ, Osteoporosis Res Ctr, 601 N 30th St 5766, Omaha, NE 68131 USA Creighton Univ 601 N 30th St 5766 Omaha NE USA 68131 68131 USA
Citazione:
D.M. Cullen et al., "Bone-loading response varies with strain magnitude and cycle number", J APP PHYSL, 91(5), 2001, pp. 1971-1976

Abstract

Mechanical loading stimulates bone formation and regulates bone size, shape, and strength. It is recognized that strain magnitude, strain rate, and frequency are variables that explain bone stimulation. Early loading studieshave shown that a low number (36) of cycles/day (cyc) induced maximal boneformation when strains were high (2,000 mu epsilon) (Rubin CT and Lanyon LE. J Bone Joint Surg Am 66: 397-402, 1984). This study examines whether cycle number directly affects the bone response to loading and whether cycle number for activation of formation varies with load magnitude at low frequency. The adult rat tibiae were loaded in four-point bending at 25 (-800 mu epsilon) or 30 N (-1,000 mu epsilon) for 0, 40, 120, or 400 cyc at 2 Hz for 3 wk. Differences in periosteal and endocortical formation were examined byhistomorphometry. Loading did not stimulate bone formation at 40 cyc. Compared with control tibiae, tibiae loaded at -800 mu epsilon showed 2.8-fold greater periosteal bone formation rate at 400 cyc but no differences in endocortical formation. Tibiae loaded at -1,000 mu epsilon and 120 or 400 cyc had 8- to 10-fold greater periosteal formation rate, 2- to 3-fold greater formation surface, and 1-fold greater endocortical formation surface than control. As applied load or strain magnitude decreased, the number of cyc required for activation of formation increased. We conclude that, at constant frequency, the number of cyc required to activate formation is dependent onstrain and that, as number of cyc increases, the bone response increases.

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Documento generato il 01/04/20 alle ore 20:42:56