Muscle Strength: Build it Better with Fish Oil and Strength Training

[frame src="/wp-content/uploads/images/PUFA4.12_Callout26.png" alt="" width="163" height="193" align="right"]Among the changes in health and function with aging are losses in muscle mass (sarcopenia), strength and function. These developments parallel those occurring in bone, to which muscle function is related. As muscle weakness and loss progress, an individual loses functional independence, incurs greater disability and faces a higher risk of mortality after bone fracture. Muscle weakness is also a predictor of major mobility disability. In addition to the consequences of time, changes in lifestyle, physical activity, nutrition and health may further undermine the strength and quality of life in the elderly. Loss of muscle strength in older adults appears to be greater in men (12% loss in leg muscle strength per decade) compared with women (2% loss per decade), despite the maintenance of muscle mass. Although these observations suggest gloom, there is encouraging news. [frame src="/wp-content/uploads/images/PUFA4.12_Photo9.png" alt="" width="261" height="221" align="left"]Changes in physical activity, strength training and nutrition have been associated with improved gait speed, stride length and cadence in 61-year-old women who performed lower limb strength training for 12 weeks. Resistance training was also associated with improved muscle strength, balance and depressive symptoms in older adults. Even Austrian skiers aged 60 to 76 years who averaged 28 days of guided alpine skiing over 12 weeks significantly increased their aerobic capacity, leg muscle power and strength compared with those who did not ski. That’s a lot of days on the slopes! Another study reported that alpine skiing increased muscle thickness, length and torque in the relevant knee and leg muscles of 67-year old men and women who took up recreational skiing for 12 weeks after experiencing sarcopenia and muscle weakness. Further, a recent study in master’s level athletes aged 40 to 81 years reported that high levels of chronic exercise (training 4 to 5 times per week) was associated with the retention of lean muscle mass in the mid-thigh and peak torque in the quadriceps. Less strenuous resistance training also improves strength and quality of life in elderly adults. These findings suggest that chronic disuse more than aging contributes to the loss of muscle mass and strength in sedentary adults. Researchers at Parana Federal University in Brazil were curious whether supplementation with fish oil might enhance the effects of strength training on skeletal muscle in older adults. Evidence suggests that fish oil or long-chain omega-3 PUFAs (n-3 LC-PUFAs) might enhance ventricular function (left ventricular ejection fraction) in patients with chronic heart failure. One study reported that n-3 LC-PUFA supplementation was associated with a greater rate of muscle protein synthesis in a small number of older adults. Low levels of DHA and other PUFAs were associated with poorer nerve function. There is also evidence that n-3 LC-PUFAs, specifically EPA, may have favorable effects on skeletal muscle metabolism and glucose utilization. Thus, it seemed plausible that fish oil might improve the effects of targeted exercise in healthy older women. There are few studies on the effects of n-3 LC-PUFAs or fish oil on neuromuscular function in healthy and older adults, so this study is exploring new territory. [frame src="/wp-content/uploads/images/PUFA4.12_Callout27.png" alt="" width="195" height="218" align="right"]For their study, the investigators recruited 45 healthy white women whose average age was 64 years. Their average body mass index was approximately 26 kg/m2 and none was receiving hormone replacement therapy or engaging in regular physical activity. After accounting for the participants’ baseline relative knee extension strength, the investigators randomly assigned the women to one of 3 experimental groups. The first group performed only strength training for 90 days; the second consumed fish oil providing approximately 400 mg of EPA and 300 mg of DHA per day and participated in strength training for 90 days; the third group consumed a similar amount of EPA and DHA for 60 days before beginning the 90-day program of strength training and continued with the supplementation for the following 90 days of training. The exercise program was designed to improve lower limb muscle strength and involved supervised resistance-training exercises 3 times/week for 12 weeks. Each group conducted their exercises at different times and days from the other groups. The volunteers received 2 weeks of exercise familiarization performed at 50% of their baseline one-repetition maximal test. The first week of the 12-week study period involved the exercises at 70% of the baseline maximal value. The second week used 80% of the baseline maximal value, with weekly adjustments thereafter to the last week of training. Descriptions of the specific exercises are given in the paper. The measured outcomes were peak torque, defined as the maximal voluntary isometric contraction from 3 trials, and the rate of torque development, defined as the slope of the force-time curve between 20% and 80% of the peak torque value. Measurements of torque and its rate of development are related to the ability to maintain balance. Inability to produce torque rapidly may jeopardize an individual’s ability to respond quickly to changes in balance. Muscle performance was assessed at baseline prior to exercise training and at the completion of the training. In those consuming fish oil prior to training, an additional assessment was conducted at the beginning of supplementation. [frame src="/wp-content/uploads/images/PUFA4.12_Photo10.1.png" alt="" width="282" height="235" align="left"] Muscle activation and electromechanical delay during maximal isometric contractions were assessed using a surface electromyography device (Noraxon Telemyo 900). Measurements from this device were used to determine the muscle activation level. The electromechanical delay was assessed as the time lag between the beginning of the electromyographic activity and the beginning of the mechanical response or torque increase. More details of these measurements are described in the original paper. These measurements reflect how quickly the muscles respond to nervous impulses from the brain. Functional capacity was determined at baseline and at the completion of resistance training. The evaluation consisted of these tests: foot-up-and-go; sit and reach; chair-rising; and 6-minute walk. An interval of 20 minutes occurred between each test. [frame src="/wp-content/uploads/images/PUFA4.12_Photo11.1.png" alt="" width="273" height="258" align="right"]The investigation’s key finding was that fish oil supplementation plus strength training was associated with improved responses in the neuromuscular system of healthy 64-year-old women who had been sedentary. As expected, a 12-week program of strength training improved all measures of peak torque and the rate of torque development compared with baseline values. When fish oil was added to the training for 90 days or 150 days, peak torque and the rate of torque development were significantly higher compared with the training program alone. There was no significant improvement with longer duration of fish oil consumption in any of the measurements except one, the activation level of the gastrocnemius muscle. In terms of functional capacity, strength training improved performance in the chair-rising exercise, foot up and go and the 6-minute walk tests, but fish oil consumption was associated with improved performance only in the chair-raising test. These results confirm others reporting improved neuromuscular performance with strength training. The authors suggest that improved rate of torque development reflects better muscle contractility, which would have positive implications for daily tasks and recovery from a slip or trip. Strength training has been associated with muscle protein anabolism in the elderly, while n-3 LC-PUFAs have been reported to augment muscle protein anabolism in healthy young and middle-aged adults. One might expect an increase in muscle mass in these participants, but the investigators did not measure change in muscle mass. Although these findings must be confirmed before adding them to the list of health benefits associated with n-3 LC-PUFAs, this study may open the door to additional research on the effect of these fatty acids in neuromuscular performance. Rodacki CL, Rodacki AL, Pereira G, Naliwaiko K, Coelho I, Pequito D, Fernandes LC. Fish-oil supplementation enhances the effects of strength training in elderly women. Am J Clin Nutr 2012;95:428-436. PubMed