Effects of Weight Training Program on Forearm Muscle Strength and Bone Mineral Density in Healthy Young Women
Abstract
Background and objective: The incidence of fractures caused by osteoporosis is increasing and forearm is one of the common sites for fractures. Mechanical loading applied to the bone can stimulate its development and adaptation leading to increase bone strength and prevent fracture. The purposes of this study were to assess the effects of weight training program on forearm muscle strength and bone mineral density in healthy young women.
Methods: Sixteen female volunteers, aged 19-23 years, were participated in a weight training program (biceps curl with a dumbbell; 70-85% of one repetition maximum (1RM), 8-12 times/set, 3 sets/day, 3 days/week) for 12 weeks. The program was performed in non-dominant arm and reassessed 1RM every 2 weeks. Changes in muscle strength (elbow flexors, wrist flexors and wrist extensors) were measured as maximal voluntary isometric contraction (MVIC) using a digital dynamometer. The bone mineral density (BMD) was assessed by dual-energy X-ray absorptiometry at before and after training at 4, 8, and 12 weeks.
Results: Both of MVIC (elbow flexors, wrist flexors and wrist extensors) and BMD (radius and ulna) showed significant increases after training compared to before training (p<0.05). The mean changes of each MVIC at the end of training were increased 2.34 (95%CI 2.04, 2.64), 1.83 (95%CI 1.64, 2.01) and 1.86 (95%CI 1.67, 2.06) kg whereas BMD were increased 0.068 (95%CI 0.050, 0.086) and 0.073 (95%CI 0.054, 0.092) g/cm2, respectively.
Conclusion: Results indicated that the 12 weeks weight training program (biceps curl with a dumbbell) increased forearm muscle and bone strength. We belief that these changes may reduce the risk of bone fracture and osteoporosis.
Key word: Weight Training Program, Muscle Strength, Bone Mineral Density
