title: Resistance training and bone mineral density during growth.
abstract: This study examined the efficacy of two different resistance training programs in enhancing bone modeling and bone mineral density (BMD) in maturating rats. One exercise mode involved lifting a lighter weight with more repetitions (LI), while the other regimen involved lifting a heavier weight with fewer repetitions (HI) where the total volume of work between exercise programs was equivalent by design. Twenty-three male rats were randomly divided into control (Con, n = 8), LI (n = 7), and HI (n = 8) groups. The LI and HI groups were conditioned to climb a vertical ladder with weights appended to their tail 4 days/wk for 6 wks. After training, serum osteocalcin (OC) was significantly (p < 0.05) higher in both HI (45.2 +/- 1.7 ng/ml) and LI (39.1 +/- 2.2 ng/ml) when compared to Con (29.9 +/- 0.9 ng/ml). Left tibial BMD was significantly (p < 0.05) greater for HI (0.231 +/- 0.004 g/cm (2)) when compared to both LI (0.213 +/- 0.003 g/cm (2)) and Con (0.206 +/- 0.005 g/cm (2)) with no significant difference between LI and Con. The results indicate that both HI and LI are effective in elevating serum OC, implicating an osteogenic response; however, only HI resulted in a significant elevation in BMD.
authors: Department of Biological Sciences, Chapman University, Orange, CA 92866, USA.
authors: M Z
authors: MZ
authors: Smith
authors: B M
authors: BM
authors: Goettsch
authors: R D
authors: RD
authors: Van Ramshorst
authors: J A
authors: JA
authors: O'Brien
authors: S V
authors: SV
authors: Jaque
authors: K D
authors: KD
authors: Sumida
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D008297:Male; D023421:Models, Animal; D009124:Muscle Proteins / Q000032:analysis; D015675:Osteocalcin / Q000097:blood; D010805:Physical Conditioning, Animal; D011897:Random Allocation; D051381:Rats / Q000254:growth & development*; D017208:Rats, Wistar; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D009124:Muscle Proteins; D015675:Osteocalcin