Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women |
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Authors: | S M Nickols-Richardson L E Miller D F Wootten W K Ramp W G Herbert |
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Institution: | (1) Department of Human Nutrition, Foods and Exercise (0430), Virginia Polytechnic Institute and State University, 225 Wallace Hall, Blacksburg, VA 24061-0430, USA;(2) Health Research Group, Rockbridge Baths, VA, USA;(3) Department of Nutritional Sciences, The Pennsylvania State University, S-129D South Henderson Bldg., University Park, PA 16802, USA |
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Abstract: | Summary Women participated in 5 months of unilateral concentric (n = 37) or eccentric (n = 33) isokinetic resistance training of the legs and arms. Limb muscular strength increased as did total body, leg, and arm
fat-free soft tissue mass, total body BMC, hip BMD, and forearm BMC and BMD. Isokinetic training benefits bone mineral acquisition.
Introduction and hypothesis Isokinetic resistance training (IRT) is osteogenic; however, it is not known if concentric or eccentric modalities of IRT
produce differential effects on bone. We tested our hypothesis that high-load eccentric versus concentric mode of IRT would
produce greater increases in muscular strength, fat-free soft tissue mass (FFSTM), bone mineral density (BMD) and content
(BMC) in trained legs and arms.
Methods Participants were randomized to 5 months of concentric (n = 37) or eccentric (n = 33) training. The non-dominant leg and arm were used during training; dominant limbs served as controls. Muscular strength
was measured with an isokinetic dynamometer; body composition was measured by dual-energy X-ray absorptiometry.
Results Muscular strength of the concentrically and eccentrically trained leg (18.6%; 28.9%) and arm (12.5%; 24.6%) significantly
increased with training. Gains in total body (TB) BMC (p < 0.05) and, in the trained limbs, total proximal femur BMD (p < 0.05) and total forearm BMD (p < 0.05) and BMC (p < 0.05) occurred in both groups. FFSTM increased for the TB and trained leg and arm (all p < 0.001) in both modes.
Conclusion Regardless of the mode, high-intensity, slow-velocity IRT increases muscular strength and FFSTM of trained limbs and imparts
benefits to TB BMC and site-specific BMD and BMC in young women. |
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Keywords: | Bone densitometry Bone mineral Mechanical loading Muscular strength Women |
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