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/cm2) when compared to both LI (0.213 ± 0.003 g/cm2) and Con (0.206 ± 0.005 g/cm2) 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.
Key words
tibia - osteocalcin - pyridinoline - DXA
References
-
1
Bassey E J, Ramsdale S J.
Increase in femoral bone density in young women following high-impact exercise.
Osteoporos Int.
1994;
4
72-75
-
2
Bennell K, Page C, Khan K, Warmington S, Plant D, Thomas D, Palamara J, Williams D, Wark J D.
Effects of resistance training on bone parameters in young and mature rats.
Clin Exp Pharmacol Physiol.
2000;
27
88-94
-
3
Bradney M, Pearce G, Naughton G, Sullivan C, Bass S, Beck T, Carlson J, Seeman E.
Moderate exercise during growth in prepubertal boys: changes in bone mass, size, volumetric density, and bone strength: a controlled prospective study.
J Bone Min Res.
1998;
13
1814-1821
-
4
Carter D R, Bouxsein M L, Marcus R.
New approaches for interpreting projected bone densitometry data.
J Bone Min Res.
1992;
7
137-145
-
5
Creighton D L, Morgan A L, Boardley D, Brolinson P G.
Weight-bearing exercise and markers of bone turnover in female athletes.
J Appl Physiol.
2001;
90
565-570
-
6
Frisch F, Sumida K D.
Strength training does not alter the effects of testosterone propionate injections on high-density lipoprotein cholesterol concentrations.
Metab.
1999;
48
1493-1497
-
7
Honda A, Naota S, Nagasawa S, Shimizu T, Umemura Y.
High-impact exercise strengthens bone in osteogenic ovariectomized rats with the same outcome as Sham rats.
J Appl Physiol.
2003;
95
1032-1037
-
8
Hornberger T A, Farrar R P.
Physiological hypertrophy of the FHL muscle following 8 weeks progressive resistance exercise in the rat.
Can J Appl Physiol.
2004;
29
16-31
-
9
Huang T H, Lin S C, Chang F L, Hsieh S S, Liu S H, Yang R S.
Effects of different exercise modes on mineralization, structure, and biochemical properties in growing bone.
J Appl Physiol.
2003;
95
300-307
-
10
Leeds E M, Wilkerson J E, Brown G D, Kamen G, Bredle D.
Effects of exercise and anabolic steroids on total and lipoprotein cholesterol concentrations in male and female rats.
Med Sci Sports Exerc.
1986;
18
663-667
-
11
Lowry O H, Rosebrough N J, Farr A L, Randall R J.
Protein measurement with the Folin phenol reagent.
J Biol Chem.
1951;
193
265-275
-
12
Morris F L, Naughton G A, Gibbs J L, Carlson J S, Wark J D.
Prospective ten-month exercise intervention in premenarcheal girls: positive effects on bone and lean mass.
J Bone Min Res.
1997;
12
1453-1462
-
13
Notomi T, Lee S J, Okimoto N, Okazaki Y, Takamoto T, Nakamura T, Suzuki M.
Effects of resistance exercise training on mass, strength, and turnover of bone in growing rats.
Eur J Appl Physiol.
2000;
82
268-274
-
14
Notomi T, Okimoto N, Okazaki Y, Tanaka Y, Nakamura T, Suzuki M.
Effects of tower climbing exercise on bone mass, strength, and turnover in growing rats.
J Bone Min Res.
2001;
16
166-174
-
15
Pruitt L A, Taaffe D R, Marcus R.
Effects of a one-year high-intensity versus low-intensity resistance training program on bone mineral density in older women.
J Bone Miner Res.
1995;
10
1788-1795
-
16
Robling A G, Burr D B, Turner C H.
Recovery periods restore mechanosensitivity to dynamically loaded bone.
J Exp Biol.
2001;
204
3389-3399
-
17
Rubin C T, Lanyon L E.
Regulation of bone formation by applied dynamic loads.
J Bone Joint Surg [Am].
1984;
66
397-402
-
18
Sale D G.
Neural adaptation to resistance training.
Med Sci Sports Exerc.
1988;
20
S135-S145
-
19
Schroeder E T, Hawkins S A, Jaque S V.
Musculoskeletal adaptations to 16 weeks of eccentric progressive resistance training in young women.
J Strength Cond Res.
2004;
18
227-235
-
20
Taaffe D R, Snow-Harter C, Connolly D A, Robinson T L, Brown M D, Marcus R.
Differential effects of swimming versus weight-bearing activity on bone mineral status of eumenorrheic athletes.
J Bone Miner Res.
1995;
10
586-593
-
21
Turner C H, Ichiro O, Takano Y.
Mechanotransduction in bone: role of strain rate.
Am J Physiol.
1995;
269
E438-E442
-
22
Westerlind K C, Fluckley J D, Gordon S E, Kraemer W J, Farrell P A, Turner R T.
Effect of resistance exercise training on cortical and cancellous bone in mature male rats.
J Appl Physiol.
1998;
84
459-464
-
23
Yeh J K, Liu C C, Aloia J F.
Effects of exercise and immobilization on bone formation and resorption in young rats.
Am J Physiol.
1993;
264
E182-E189
Dr. PhD Ken D. Sumida
Department of Biological Sciences
Chapman University
One University Drive
Orange, CA 92866
United States
Phone: + 1 71 49 97 69 95
Fax: + 1 71 45 32 60 48
Email: sumida@chapman.edu