Fish Oil Supplementation Improves Muscle Function in Elderly Brazilian Women

High n-6 PUFA intake, as commonly seen in Western-style diets, can lead to a net increase in pro-inflammatory cytokines that may lead to tissue damage, including muscle tissue.

17 April 2012 --- Aging is accompanied by decreases in functional capacity that can degrade the quality of life.  Changes in function associated with aging include declines in the neuromuscular system, such as morphologic and phenotypic changes, changes in the size of muscle fibers and loss of muscle mass and strength.  Among the detrimental age-associated neuromuscular changes, the ability to generate muscle torque and the rate at which this torque can be developed declines.  However, studies have shown that these altered neuromuscular effects can be reversed or attenuated through strength training.  In addition, neural degenerative disorders of the central and/or peripheral nervous system, low physical activity level and nutritional changes associated with aging may exacerbate these changes in muscle function.

Dietary intake of fatty acids, such as n-6 and n-3 polyunsaturated fatty acids (PUFA) can influence the inflammatory environment. High n-6 PUFA intake, as commonly seen in Western-style diets, can lead to a net increase in pro-inflammatory cytokines that may lead to tissue damage, including muscle tissue.  In contrast, n-3 PUFA can exert anti-inflammatory effects that may be protective against a variety of age-related diseases. Fish oil is rich in n-3 PUFA, such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), and has been shown to influence nerve conduction velocity and cardiac contractile activity.  Given the potential positive effects of fish oil, it is reasonable to explore the possibility that the effects of strength training on skeletal muscles may be enhanced by increased fish oil intake.

In a recent study conducted by Brazilian researchers, 45 healthy elderly white women, aged 64 years, were randomly assigned to one of three experimental groups. One group performed strength training alone for 90 days.  A second group was supplemented with fish oil throughout the 90 days strength training treatment, and the third group was started on fish oil supplementation for 60 days before beginning the 90-day strength training and fish oil period.  All of the subjects who were supplemented received 2 g per day of fish oil, which provided 0.4 g of EPA and 0.3 g of DHA.  Otherwise, the participants maintained their normal eating habits and physical activity throughout the study. The focus of the strength training exercises was to improve lower limb muscle strength.  This strength training exercise was performed three times per week for 90 days. Assessments of neuromuscular and functional capacity were performed before and after the training.

No change in body mass and dietary intake were observed between the pre-and post-training assessments.  There was no change in plasma EPA and DHA levels in the group that received strength training alone.  The group that received strength training and 90 days of fish oil supplementation experienced a significant increase in EPA and DHA concentration.  Likewise, the strength training group that received 150 days of fish oil supplementation (60 days prior to exercise treatment and 90 days during exercise training) also experienced significant increases in plasma EPA and DHA concentrations.

Importantly, at the start of the study and prior to training there were no differences in peak muscle torque measurements among the three study groups.  As expected, strength training increased peak torque in those lower limb muscles assessed. Interestingly, fish oil supplementation resulted in a significantly higher peak torque post-training than in the strength training group alone.  However, the longer fish oil supplementation period of 150 days did not cause any additive effect on peak muscle torque and the results were similar to the group that received fish oil for only 90 days. Another measure of neuromuscular function, called the rate of torque development (RTD), also indicated that strength training was associated with a significant increase; but, fish oil supplementation was associated with a significantly higher RTD post-training than in the strength training group alone.  Also, as seen with the measure of peak torque, longer supplementation with fish oil did not cause an additive effect and the results were similar to those seen for the 90 day fish oil supplementation group.  Muscle activation level was also determined in the subjects, and it was found that fish oil supplementation increased muscle activation level compared to strength training alone. Finally, functional capacity was determined by a series of physical performance tests.  In one of these tests, which measured the ability to rise from a sitting position in a chair, strength training increased this measure of functional capacity, and supplementation with fish oil induced a further increase in the score on the chair-rising test.

A key finding from this study was that fish oil supplementation, along with strength training, was able to improve the response of the neuromuscular system in elderly women. Other important findings from this study indicate that the doses of EPA and DHA delivered (0.4 and 0.3 g/day) were sufficient to cause a functional response in these elderly women.  In addition, the observation that fish oil supplementation beyond 90 days was without additional benefit suggests that these changes occur relatively early in response to fish oil supplementation. The researchers suggest that fish oil supplementation may be an attractive supplement for the elderly to help maximize their neuromuscular responses to strength training, which could have important effects on their quality of life.