Fish-oil Supplementation Enhances the Effects of Strength Training in Elderly Women
SOURCE: Am J Clin Nutr. 2012 (Feb); 95 (2): 428–436
Cintia LN Rodacki, André LF Rodacki,
Gleber Pereira, Katya Naliwaiko,
Paraná Federal University,
Setor de Ciências Biológicas,
Curitiba, Paraná, Brazil.
BACKGROUND: Muscle force and functional capacity generally decrease with aging in the older population, although this effect can be reversed, attenuated, or both through strength training. Fish oil (FO), which is rich in n-3 (omega-3) polyunsaturated fatty acids (PUFAs), has been shown to play a role in the plasma membrane and cell function of muscles, which may enhance the benefits of training. The effect of strength training and FO supplementation on the neuromuscular system of the elderly has not been investigated.
OBJECTIVE: The objective was to investigate the chronic effect of FO supplementation and strength training on the neuromuscular system (muscle strength and functional capacity) of older women.
DESIGN: Forty-five women (aged 64 ± 1.4 y) were randomly assigned to 3 groups. One group performed strength training only (ST group) for 90 d, whereas the others performed the same strength-training program and received FO supplementation (2 g/d) for 90 d (ST90 group) or for 150 d (ST150 group; supplemented 60 d before training). Muscle strength and functional capacity were assessed before and after the training period.
RESULTS: No differences in the pretraining period were found between groups for any of the variables. The peak torque and rate of torque development for all muscles (knee flexor and extensor, plantar and dorsiflexor) increased from pre- to posttraining in all groups. However, the effect was greater in the ST90 and ST150 groups than in the ST group. The activation level and electromechanical delay of the muscles changed from pre- to posttraining only for the ST90 and ST150 groups. Chair-rising performance in the FO groups was higher than in the ST group.
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CONCLUSIONS: Strength training increased muscle strength in elderly women. The inclusion of FO supplementation caused greater improvements in muscle strength and functional capacity.
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INTRODUCTION
The ability of skeletal muscles to generate torque and the rate at which this torque is developed are reduced by aging. [1] Such a phenomena occurs due to changes in the neuromuscular system, including morphologic and phenotypic changes, change in size of muscle fibers, and loss of muscle mass [2]; neural degenerative disorders of the central and/or peripheral nervous system [3]; low physical activity level; and nutritional changes. [4] Therefore, different strategies to attenuate or reverse the decline of the neuromuscular system in the elderly are advised. Indeed, it has been shown that strength training is able to attenuate and/or partially reverse the functional capacity reduction of the neuromuscular system ability in the elderly. [5]
Some studies report that strength training increases peak torque and RTD [4–6], as well as functional capacity. [7] In addition, the neural excitability is improved after a strength-training program, which decreases the EMD—ie, the time between the electrical stimulation and the mechanical response of muscle. [8] This suggests that strength training can induce neuromuscular adjustment in older individuals, leading to improvements in the quality of life.
Western diets are high in n–6 and low in n–3 polyunsaturated fatty acids (PUFAs), which compete for incorporation into the labile second position of phospholipids in the cell membranes. n–6 PUFAs, mainly linoleic acid, is a precursor of arachidonic acid, which is a substrate of cyclooxygenase and lipoxygenase enzymes that leads to a net proinflammatory environment that will cause damage in several tissues, including muscles. On the other hand, n–3 PUFAs exert pleiotropic actions on many tissues, particularly in the cardiovascular and central nervous systems, that might be protective against age-related diseases. The central nervous system has a high concentration of complex lipids, which determine the structural and functional properties of its cellular and subcellular membranes. [9–11] FO supplementation, which is rich in n–3 PUFAs, has been shown to increase nerve conduction velocity in the elderly [12], sarcolemma ion channel modulation [13], and improved heart contractile activity. [14] Thus, because FO supplementation improves both cardiac muscle contractility [15] and nerve conduction velocity, it is reasonable to hypothesize that it may potentiate strength-training effects on skeletal muscles. There is a dearth of studies that report the effects of FO supplementation on neuromuscular function in the elderly and a lack of information regarding the length of supplementation and dose.
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