title: Strength training increases regional bone mineral density and bone remodeling in middle-aged and older men.
abstract: To determine the effects of strength training (ST) on bone mineral density (BMD) and bone remodeling, 18 previously inactive untrained males [mean age 59 +/- 2 (SE) yr] were studied before and after 16 wk of either ST (n = 11) or no exercise (inactive controls; n = 7). Total, spinal (L2-L4), and femoral neck BMD were measured in nine training and seven control subjects before and after the experimental period. Serum concentrations of osteocalcin, skeletal alkaline phosphatase isoenzyme, and tartrate-resistant acid phosphatase were measured before, during, and after the experimental program in all subjects. Training increased muscular strength by an average of 45 +/- 3% (P < 0.001) on a three-repetition maximum test and by 32 +/- 4% (P < 0.001) on an isokinetic test of the knee extensors performed at 60 degrees/s. BMD increased in the femoral neck by 3.8 +/- 1.0% (0.900 +/- 0.05 vs. 0.933 +/- 0.05 g/cm2, P < 0.05) and in the lumbar spine by 2.0 +/- 0.9% (1.180 +/- 0.06 vs. 1.203 +/- 0.06 g/cm2, P < 0.05). However, changes in lumbar spine BMD were not significantly different from those in the control group. There was no significant change in total body BMD. Osteocalcin increased by 19 +/- 6% after 12 wk of training (P < 0.05) and remained significantly elevated after 16 wk of training (P < 0.05). There was a 26 +/- 11% increase in skeletal alkaline phosphatase isoenzyme levels (P < 0.05) after 16 wk of training.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: University of Maryland, Department of Kinesiology, College Park 20742.
authors.forename: A
authors.initials: A
authors.lastname: Menkes
authors.forename: S
authors.initials: S
authors.lastname: Mazel
authors.forename: R A
authors.initials: RA
authors.lastname: Redmond
authors.forename: K
authors.initials: K
authors.lastname: Koffler
authors.forename: C R
authors.initials: CR
authors.lastname: Libanati
authors.forename: C M
authors.initials: CM
authors.lastname: Gundberg
authors.forename: T M
authors.initials: TM
authors.lastname: Zizic
authors.forename: J M
authors.initials: JM
authors.lastname: Hagberg
authors.forename: R E
authors.initials: RE
authors.lastname: Pratley
authors.forename: B F
authors.initials: BF
authors.lastname: Hurley
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000368:Aged; D000469:Alkaline Phosphatase / Q000378:metabolism; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology*; D001842:Bone and Bones / Q000201:enzymology; D004032:Diet; D006801:Humans; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training; D014891:Weight Lifting
chemical_list: D015675:Osteocalcin; D000469:Alkaline Phosphatase; D000135:Acid Phosphatase