Fish-oil supplementation enhances the effects of strength training in elderly women

Supplements with purported effects on muscle mass and strength

PURPOSE

Several supplements are purported to promote muscle hypertrophy and strength gains in healthy subjects, or to prevent muscle wasting in atrophying situations (e.g., ageing or disuse periods). However, their effectiveness remains unclear.

METHODS

This review summarizes the available evidence on the beneficial impacts of several popular supplements on muscle mass or strength.

RESULTS

Among the supplements tested, nitrate and caffeine returned sufficient evidence supporting their acute beneficial effects on muscle strength, whereas the long-term consumption of creatine, protein and polyunsaturated fatty acids seems to consistently increase or preserve muscle mass and strength (evidence level A). On the other hand, mixed or unclear evidence was found for several popular supplements including branched-chain amino acids, adenosine triphosphate, citrulline, β-Hydroxy-β-methylbutyrate, minerals, most vitamins, phosphatidic acid or arginine (evidence level B), weak or scarce evidence was found for conjugated linoleic acid, glutamine, resveratrol, tribulus terrestris or ursolic acid (evidence level C), and no evidence was found for other supplements such as ornithine or α-ketoglutarate (evidence D). Of note, although most supplements appear to be safe when consumed at typical doses, some adverse events have been reported for some of them (e.g., caffeine, vitamins, α-ketoglutarate, tribulus terrestris, arginine) after large intakes, and there is insufficient evidence to determine the safety of many frequently used supplements (e.g., ornithine, conjugated linoleic acid, ursolic acid).

CONCLUSION

 In summary, despite their popularity, there is little evidence supporting the use of most supplements, and some of them have been even proven ineffective or potentially associated with adverse effects.

Omega-3 Polyunsaturated Fatty Acids: Benefits and Endpoints in Sport

The influence of nutrition has the potential to substantially affect physical function and body metabolism. Particular attention has been focused on omega-3 polyunsaturated fatty acids (n-3 PUFAs), which can be found both in terrestrial features and in the marine world. They are responsible for numerous cellular functions, such as signaling, cell membrane fluidity, and structural maintenance. They also regulate the nervous system, blood pressure, hematic clotting, glucose tolerance, and inflammatory processes, which may be useful in all inflammatory conditions. Animal models and cell-based models show that n-3 PUFAs can influence skeletal muscle metabolism. Furthermore, recent human studies demonstrate that they can influence not only the exercise and the metabolic response of skeletal muscle, but also the functional response for a period of exercise training. In addition, their potential anti-inflammatory and antioxidant activity may provide health benefits and performance improvement especially in those who practice physical activity, due to their increased reactive oxygen production. This review highlights the importance of n-3 PUFAs in our diet, which focuses on their potential healthy effects in sport.

Omega-3 supplementation with resistance training does not improve body composition or lower biomarkers of inflammation more so than resistance training alone in older men

The purpose of this study was to evaluate the effectiveness of 3.0 g/d of omega-3 fatty acid (eicosapentaenoic acid and docosahexaenoic acid) supplementation combined with progressive resistance training to improve body composition and lower inflammatory cytokines in older men when compared to placebo and resistance training. We hypothesized that completing a 12-week omega-3 supplementation period along with whole body resistance exercise (3 times/wk) would result in a significantly greater improvement in lean tissue mass as well as a significant decrease in interleukin-6 and tumor necrosis factor-α when compared to placebo. A total of 23 older men (≥65 years old) were randomized to an omega-3 supplementation group (n = 11) or placebo group (n = 12), and all the participants completed the same whole body progressive resistance training program. Baseline and 12-week data collection included body composition, muscle strength, functional ability, and inflammatory cytokines. Results indicated a significant main effect for time (all P < .05) for percent body fat (-2.5%), lean tissue mass (+1.1%), lumbar bone mineral density (+1.1%), hip bone mineral content (+1.1%), chest press strength (+31%), leg press strength (+37%), timed-up-and-go (-6.6%), and 6-minute walk distance (+4.5%) from baseline to post 12 weeks. No significant effects were noted for the 2 inflammatory cytokines measured (P > .05). We conclude that progressive resistance training exercise is an excellent method to enhance parameters of body composition, skeletal muscle strength, and functional ability in older men, whereas omega-3 supplementation did nothing to enhance these parameters or influence inflammatory biomarkers.

Association of Handgrip Strength with Dietary Intake in the Korean Population: Findings Based on the Seventh Korea National Health and Nutrition Examination Survey (KNHANES VII-1), 2016

To evaluate associations between handgrip strength (HGS) and dietary nutrients, this study of a representative Korean population of 1553 adults aged ≥60 years (706 men and 847 women) analyzed data from the Korea National Health and Nutrition Examination Survey (2016). HGS was measured in both hands three times using a digital grip strength dynamometer. Dietary intake data were collected by the 24-h recall method through computer-assisted personal interviews. The study population had a mean age of 70.1 years, body mass index (BMI) of 24.2 kg/m², and HGS of 35.7 kg in men, 21.2 kg in women. Total energy (r = 0.411), protein (r = 0.217), polyunsaturated fatty acid (PUFA) (r = 0.269), fiber (r = 0.272), and vitamin C (r = 0.098) were positively correlated with HGS. In multivariable regression analysis, PUFA (β = 0.083) and vitamin C (β = 0.003) were positively associated with HGS among women. Fiber (β = 0.071) and vitamin C (β = 0.006) showed a positive association with HGS among men. Community-dwelling older men and women with higher levels of PUFA, fiber, and vitamin C in their diet were more likely to have greater HGS even after adjusting for age, total calorie intake, BMI, chronic diseases and health-related habits.

The impact of exercise and nutrition on the regulation of skeletal muscle mass

The maintenance of skeletal muscle mass and strength throughout life is a key determinant of human health and well-being. There is a gradual loss of both skeletal muscle mass and strength with ageing (a process termed sarcopenia) that increases the risk of functional dependence, morbidity and mortality. Understanding the factors that regulate the size of human muscle mass, particularly during the later years of life, has therefore become an area of intense scientific inquiry. The amount of muscle mass is determined by coordinated changes in muscle protein synthesis (MPS) and muscle protein breakdown (MPB). In this review, we assess both classical and contemporary work that has examined how resistance exercise and nutrition impact on MPS and MPB. Special consideration is given to the role of different sources of dietary protein (food vs. supplements) and non-protein nutrients such as omega-3 fatty acids in regulating MPS. We also critically evaluate recent studies that have employed novel 'omic' technologies such as dynamic protein profiling to probe for changes in rates of MPS and MPB at the individual protein level following exercise. Finally, we provide suggestions for future research that we hope will yield important information for the development of exercise and nutritional strategies to counteract muscle loss in a variety of clinical settings.

Lipid remodeling and an altered membrane-associated proteome may drive the differential effects of EPA and DHA treatment on skeletal muscle glucose uptake and protein accretion

In striated muscle, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have differential effects on the metabolism of glucose and differential effects on the metabolism of protein. We have shown that, despite similar incorporation, treatment of C₂C₁₂ myotubes (CM) with EPA but not DHA improves glucose uptake and protein accretion. We hypothesized that these differential effects of EPA and DHA may be due to divergent shifts in lipidomic profiles leading to altered proteomic profiles. We therefore carried out an assessment of the impact of treating CM with EPA and DHA on lipidomic and proteomic profiles. Fatty acid methyl esters (FAME) analysis revealed that both EPA and DHA led to similar but substantials changes in fatty acid profiles with the exception of arachidonic acid, which was decreased only by DHA, and docosapentanoic acid (DPA), which was increased only by EPA treatment. Global lipidomic analysis showed that EPA and DHA induced large alterations in the cellular lipid profiles and in particular, the phospholipid classes. Subsequent targeted analysis confirmed that the most differentially regulated species were phosphatidylcholines and phosphatidylethanolamines containing long-chain fatty acids with five (EPA treatment) or six (DHA treatment) double bonds. As these are typically membrane-associated lipid species we hypothesized that these treatments differentially altered the membrane-associated proteome. Stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics of the membrane fraction revealed significant divergence in the effects of EPA and DHA on the membrane-associated proteome. We conclude that the EPA-specific increase in polyunsaturated long-chain fatty acids in the phospholipid fraction is associated with an altered membrane-associated proteome and these may be critical events in the metabolic remodeling induced by EPA treatment.

Targeted lipidomics analysis identified altered serum lipid profiles in patients with polymyositis and dermatomyositis

BACKGROUND

Polymyositis (PM) and dermatomyositis (DM) are severe chronic autoimmune diseases, characterized by muscle fatigue and low muscle endurance. Conventional treatment includes high doses of glucocorticoids and immunosuppressive drugs; however, few patients recover full muscle function. One explanation of the persistent muscle weakness could be altered lipid metabolism in PM/DM muscle tissue as we previously reported. Using a targeted lipidomic approach we aimed to characterize serum lipid profiles in patients with PM/DM compared to healthy individuals (HI) in a cross-sectional study. Also, in the longitudinal study we compared serum lipid profiles in patients newly diagnosed with PM/DM before and after immunosuppressive treatment.

METHODS

Lipidomic profiles were analyzed in serum samples from 13 patients with PM/DM, 12 HI and 8 patients newly diagnosed with PM/DM before and after conventional immunosuppressive treatment using liquid chromatography tandem mass spectrometry (LC-MS/MS) and a gas-chromatography flame ionization detector (GC-FID). Functional Index (FI), as a test of muscle performance and serum levels of creatine kinase (s-CK) as a proxy for disease activity were analyzed.

RESULTS

The fatty acid (FA) composition of total serum lipids was altered in patients with PM/DM compared to HI; the levels of palmitic (16:0) acid were significantly higher while the levels of arachidonic (20:4, n-6) acid were significantly lower in patients with PM/DM. The profiles of serum phosphatidylcholine and triacylglycerol species were changed in patients with PM/DM compared to HI, suggesting disproportionate levels of saturated and polyunsaturated FAs that might have negative effects on muscle performance. After immunosuppressive treatment the total serum lipid levels of eicosadienoic (20:2, n-6) and eicosapentaenoic (20:5, n-3) acids were increased and serum phospholipid profiles were altered in patients with PM/DM. The correlation between FI or s-CK and levels of several lipid species indicate the important role of lipid changes in muscle performance and inflammation.

CONCLUSIONS

Serum lipids profiles are significantly altered in patients with PM/DM compared to HI. Moreover, immunosuppressive treatment in patients newly diagnosed with PM/DM significantly affected serum lipid profiles. These findings provide new evidence of the dysregulated lipid metabolism in patients with PM/DM that could possibly contribute to low muscle performance.

Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) in Muscle Damage and Function

Nutritional supplementation not only helps in improving and maintaining performance in sports and exercise, but also contributes in reducing exercise fatigue and in recovery from exhaustion. Fish oil contains large amounts of omega-3 fatty acids, eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3). It is widely known that omega-3 fatty acids are effective for improving cardiac function, depression, cognitive function, and blood as well as lowering blood pressure. In the relationship between omega-3 fatty acids and exercise performance, previous studies have been predicted improved endurance performance, antioxidant and anti-inflammatory responses, and effectivity against delayed-onset muscle soreness. However, the optimal dose, duration, and timing remain unclear. This review focuses on the effects of omega-3 fatty acid on muscle damage and function as evaluated by human and animal studies and summarizes its effects on muscle and nerve damage, and muscle mass and strength.

The Effects of Krill Oil on mTOR Signaling and Resistance Exercise: A Pilot Study

INTRODUCTION

Krill oil supplementation has been shown to improve postexercise immune function; however, its effect on muscle hypertrophy is currently unknown. Therefore, the aim of present study was to investigate the ability of krill oil to stimulate mTOR signaling and its ability to augment resistance training-induced changes in body composition and performance.

METHODS

C2C12 myoblasts cells were stimulated with krill oil or soy-derived phosphatidylcholine (S-PC), and then, the ratio of P-p70-389 to total p70 was used as readout for mTOR signaling. In double-blind, placebo-controlled study, resistance trained subjects consumed either 3 g krill oil daily or placebo, and each took part in an 8-week periodized resistance training program. Body composition, maximal strength, peak power, and rate of perceived recovery were assessed collectively at the end of weeks 0 and 8. In addition, safety parameters (comprehensive metabolic panel (CMP), complete blood count (CBC), and urine analysis (UA)) and cognitive performance were measured pre- and posttesting.

RESULTS

Krill oil significantly stimulated mTOR signaling in comparison to S-PC and control. No differences for markers on the CMP, CBC, or UA were observed. Krill oil significantly increased lean body mass from baseline (p=0.021, 1.4 kg, +2.1%); however, there were no statistically significant differences between groups for any measures taken.

CONCLUSION

Krill oil activates mTOR signaling. Krill oil supplementation in athletes is safe, and its effect on resistance exercise deserves further research.

Effect of Protein or Essential Amino Acid Supplementation During Prolonged Resistance Exercise Training in Older Adults on Body Composition, Muscle Strength, and Physical Performance Parameters: A Systematic Review

Objectives:

Loss of muscle mass and strength with aging, sarcopenia, burdens many older adults, making identification of strategies on how to counteract it very relevant—especially to health care providers working in rehabilitation. The aim of this systematic review was to determine the effect of protein or essential amino acid (EAA) supplementation during prolonged resistance exercise training (RT) in older adults. No known stimulants of muscle protein synthesis, or ingredients with an effect on muscle strength/physical function, were allowed with the supplementation, differentiating this systematic review from others.

Data sources and methods:

In January 2017, 4 electronic databases and reference lists were searched for randomized controlled trials investigating the effect of protein or EAA supplementation during RT in older adults (mean age >60 years) on outcomes of body composition, muscle strength, and physical performance. Study selection and data extraction were performed by 2 independent reviewers.

Results

Sixteen studies (1107 participants) fulfilled the eligibility criteria. Methodologic differences between the studies disallowed a meta-analysis. Of the 16 studies, 6 found significant effects on body composition (3 studies), muscle strength (3 studies), and physical performance (2 studies) measures.

Conclusions

The evidence is weak and inconsistent, as benefit of protein or EAA supplementation during RT in older adults is only shown in some studies. The findings indicate that frail/sarcopenic older adults might benefit more than healthy older adults. Further research is needed to allow an interpretation on the importance of study population and design.

Trial registration:

PROSPERO, Reg. no.: CRD42017063808. Registered April 14, 2017.

Potential Roles of n-3 PUFAs during Skeletal Muscle Growth and Regeneration

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), which are commonly found in fish oil supplements, are known to possess anti-inflammatory properties and more recently alter skeletal muscle function. In this review, we discuss novel findings related to how n-3 PUFAs modulate molecular signaling responsible for growth and hypertrophy as well as the activity of muscle stem cells. Muscle stem cells commonly known as satellite cells, are primarily responsible for driving the skeletal muscle repair process to potentially damaging stimuli, such as mechanical stress elicited by exercise contraction. To date, there is a paucity of human investigations related to the effects of n-3 PUFAs on satellite cell content and activity. Based on current in vitro investigations, this review focuses on novel mechanisms linking n-3 PUFA’s to satellite cell activity and how they may improve muscle repair. Understanding the role of n-3 PUFAs during muscle growth and regeneration in association with exercise could lead to the development of novel supplementation strategies that increase muscle mass and strength, therefore possibly reducing the burden of muscle wasting with age.

Effects of multidomain lifestyle intervention, omega-3 supplementation or their combination on physical activity levels in older adults: secondary analysis of the Multidomain Alzheimer Preventive Trial (MAPT) randomised controlled trial

Background/objectives

to investigate the effects of a 3-year multidomain lifestyle intervention, omega-3 supplementation or both on physical activity (PA) in older adults with subjective memory complaints.

Design/settings/subjects

the Multidomain Alzheimer Preventive Trial was a 3-year randomised controlled trial that enroled 1,680 community-dwelling adults aged 70 years or over, with subjective memory complaints. Participants were randomised to omega-3 supplementation (total daily dose of 800 mg docosahexanoic acid and up to 225 mg eicosapentanoic acid), multidomain intervention (nutritional and exercise counselling and cognitive training), omega-3 plus multidomain intervention or placebo with usual care.

Methods

PA was assessed using a self-reported questionnaire. From this, global moderate-to-vigorous PA, leisure-time PA, non-leisure-time PA and light PA were measured in metabolic equivalent tasks-minutes per week (MET-min/week).

Results

in the multidomain groups, participants significantly increased their moderate-to-vigorous and leisure-time PA at 6 months (≥300 MET-min/week for both in the multidomain groups; P ≤ 0.002) before returning to baseline by the end of the trial. Activity in the placebo/usual care and omega-3/usual care groups declined overtime. Between-group differences remained significant for both multidomain groups for leisure-time physical activity at 2- and 3-year follow-ups. Compared to placebo/usual care, interventions had no significant effects on non-leisure-time PA and light PA. Omega-3 supplementation alone had no effects on PA.

Conclusions

a multidomain intervention focused on cognitive training, and nutritional and PA counselling increased PA in the short-term and limited its decline in the long-term among older adults with memory complaints. ClinicalTrials.gov-Registration number: NCT0067268.

Fish oil-derived n-3 polyunsaturated fatty acids for the prevention and treatment of sarcopenia

PURPOSE OF REVIEW

Muscle mass and function decline progressively starting in middle age, which can result in sarcopenia and affect people's mobility and independence later in life. Exercise training and increased protein intake are typically recommended to counteract the age-associated decline in muscle mass and function. However, few people comply with exercise recommendations and the effectiveness of high-protein intake to halt the decline in muscle mass and function has not been proven. This review aims to explore recent developments in the potential for fish-oil derived n-3 polyunsaturated fatty acids (n-3 PUFA) to improve muscle mass and function in older people.

RECENT FINDINGS

The results from several recent studies demonstrate that dietary supplementation with fish oil-derived n-3 PUFA stimulates muscle protein synthesis and improves muscle mass and function in sedentary older adults and augments the resistance exercise training-induced increase in muscle strength in older adults. The exact mechanisms by which fish oil-derived n-3 PUFAs exert their beneficial effects on muscle mass and function remain to be elucidated.

SUMMARY

Fish-oil supplementation has antisarcopenic effects and should be considered in the clinical care of older adults.

Is fish oil supplementation effective on maternal serum FBS, oral glucose tolerance test, hemoglobin and hematocrit in low risk pregnant women? A triple-blind randomized controlled trial

Background

Fish oil contains polyunsaturated fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which were considered as essential fatty acids. The purpose of present study was to evaluate the effects of fish oil supplementation on maternal serum fasting blood sugar (FBS), oral glucose tolerance test (OGTT), hemoglobin (Hb), and hematocrit (Hct).

Methods

In this randomized triple-blind clinical trial, 150 pregnant women were allocated into two groups randomly. In the intervention group, women received one fish oil capsule daily (1,000 mg consisted of 120 mg DHA and 180 mg EPA), and control group received placebo from the end of twentieth week of pregnancy until delivery (140 capsules). FBS, 2-hour 75 g OGTT, Hb, and Hct were measured at 6–10 and 26–30 weeks of pregnancy. Analysis was based on intervention to treat.

Results

At the weeks 26–30, mean FBS in the intervention and control groups were 76.92 (9.8) and 75.64 (8.2) mg/dl, respectively [adjusted mean difference (aMD) (95% CI):1.46 (−2.13 to 5.05)]. Also, there was no significant difference between two groups in 2-hour OGTT [aMD (95% CI): −4.69 (−13.75 to 4.52)]. Mean (SD) Hb was 11.8 (1.1) versus 11.8 (0.7) g/dl in the intervention and control groups, respectively [aMD (95% CI): 0.001 (−0.328 to 0.330)], mean (SD) Hct were 36.12% (2.8%) and 35.84% (2.3%), respectively [aMD (95% CI): 0.25 (−0.65 to 1.14)].

Conclusions

Based on the findings of present study, fish oil supplementation has no significant effect on Hb, Hct, FBS and 2-hour OGTT of pregnant women.

Omega-3 fatty acids in obesity and metabolic syndrome: a mechanistic update

Strategies to reduce obesity have become public health priorities as the prevalence of obesity has risen in the United States and around the world. While the anti-inflammatory and hypotriglyceridemic properties of long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) are well known, their antiobesity effects and efficacy against metabolic syndrome, especially in humans, are still under debate. In animal models, evidence consistently suggests a role for n-3 PUFAs in reducing fat mass, particularly in the retroperitoneal and epididymal regions. In humans, however, published research suggests that though n-3 PUFAs may not aid weight loss, they may attenuate further weight gain and could be useful in the diet or as a supplement to help maintain weight loss. Proposed mechanisms by which n-3 PUFAs may work to improve body composition and counteract obesity-related metabolic changes include modulating lipid metabolism; regulating adipokines, such as adiponectin and leptin; alleviating adipose tissue inflammation; promoting adipogenesis and altering epigenetic mechanisms.

A role for nutritional intervention in addressing the aging neuromuscular junction

The purpose of this review is to discuss the structural and physiological changes that underlie age-related neuromuscular dysfunction and to summarize current evidence on the potential role of nutritional interventions on neuromuscular dysfunction-associated pathways. Age-related neuromuscular deficits are known to coincide with distinct changes in the central and peripheral nervous system, in the neuromuscular system, and systemically. Although many features contribute to the age-related decline in neuromuscular function, a comprehensive understanding of their integration and temporal relationship is needed. Nonetheless, many nutrients and ingredients show promise in modulating neuromuscular output by counteracting the age-related changes that coincide with neuromuscular dysfunction. In particular, dietary supplements, such as vitamin D, omega-3 fatty acids, β-hydroxy-β-methylbutyrate, creatine, and dietary phospholipids, demonstrate potential in ameliorating age-related neuromuscular dysfunction. However, current evidence seldom directly assesses neuromuscular outcomes and is not always in the context of aging. Additional clinical research studies are needed to confirm the benefits of dietary supplements on neuromuscular function, as well as to define the appropriate population, dosage, and duration for intervention.

Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food Consumption

Dietary protein ingestion is critical to maintaining the quality and quantity of skeletal muscle mass throughout adult life. The performance of acute exercise enhances muscle protein remodeling by stimulating protein synthesis rates for several hours after each bout, which can be optimized by consuming protein during the post-exercise recovery period. To date, the majority of the evidence regarding protein intake to optimize post-exercise muscle protein synthesis rates is limited to isolated protein sources. However, it is more common to ingest whole food sources of protein within a normal eating pattern. Emerging evidence demonstrates a promising role for the ingestion of whole foods as an effective nutritional strategy to support muscle protein remodeling and recovery after exercise. This review aims to evaluate the efficacy of the ingestion of nutrient-rich and protein-dense whole foods to support post-exercise muscle protein remodeling and recovery with pertinence towards physically active people.

Mediterranean Diet attenuates risk of frailty and sarcopenia: New insights and future directions

Sarcopenia and physical frailty are associated with progressive disability and predictive of negative health outcomes. Dietary interventions are considered the cornerstone in the management of sarcopenic symptomology and physical frailty. However few studies have investigated preventative strategies. Moreover, most studies have focused on the efficacy of individual nutrients or supplements rather than dietary patterns. The Mediterranean Diet (MedDiet) is a dietary pattern that provides evidence for an association between diet quality, healthy ageing and disease prevention. The purpose of this paper was to examine, synthesise and develop a narrative review of the current literature, investigating the potential benefits associated with adherence to a MedDiet and attenuation of physical frailty and sarcopenic symptomology in older adults. We also explored the underlying mechanisms underpinning the potential benefits of the MedDiet on ameliorating physical frailty and sarcopenic symptomology. Synthesis of the reviewed literature is suggestive of a decreased risk of physical frailty and sarcopenic symptomology with greater adherence to a MedDiet. We identified the anti-inflammatory and high antioxidant components of the MedDiet as two potential biological mechanisms involved. Due to a lack of evidence from RCTs to support the proposed physiological mechanisms, we suggest investigating these observations in older adults with type 2 diabetes (T2DM) whom are vulnerable to physical frailty and disability. A number of biological mechanisms describing the pathway to disability in older adults with T2DM have been postulated with many of these mechanisms potentially mitigated with dietary interventions involving the MedDiet. Exploring these mechanisms with the use of well-designed, longer-term dietary intervention studies in older adults with an increased vulnerability to physical frailty and sarcopenia is warranted.  

The Role of Inflammation in Age-Related Sarcopenia

Many physiological changes occur with aging. These changes often, directly or indirectly, result in a deterioration of the quality of life and even in a shortening of life expectancy. Besides increased levels of reactive oxygen species, DNA damage and cell apoptosis, another important factor affecting the aging process involves a systemic chronic low-grade inflammation. This condition has already been shown to be interrelated with several (sub)clinical conditions, such as insulin resistance, atherosclerosis and Alzheimer's disease. Recent evidence, however, shows that chronic low-grade inflammation also contributes to the loss of muscle mass, strength and functionality, referred to as sarcopenia, as it affects both muscle protein breakdown and synthesis through several signaling pathways. Classic interventions to counteract age-related muscle wasting mainly focus on resistance training and/or protein supplementation to overcome the anabolic inflexibility from which elderly suffer. Although the elderly benefit from these classic interventions, the therapeutic potential of anti-inflammatory strategies is of great interest, as these might add up to/support the anabolic effect of resistance exercise and/or protein supplementation. In this review, the molecular interaction between inflammation, anabolic sensitivity and muscle protein metabolism in sarcopenic elderly will be addressed.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

Effect of conjugated linoleic acids and omega-3 fatty acids with or without resistance training on muscle mass in high-fat diet-fed middle-aged mice

NEW FINDINGS

What is the central question of this study? This study examined the effects of 20 weeks of administration of conjugated linoleic acids/omega-3 fatty acids with or without programed resistance exercise training on body composition, skeletal muscle properties and functional capacity in middle-aged mice fed a high-fat diet. What is the main finding and its importance? Chronic daily administration of conjugated linoleic acids/omega-3 fatty acids with resistance exercise training can help to blunt fat gain, alleviate loss of myogenic capacity and sensorimotor function and lower tissue inflammation in middle-aged mice during chronic high-fat diet-induced catabolism. This study investigated the effects of 20 weeks of combined conjugated linoleic acid (CLA)/omega-3 fatty acid (n-3) administration independently or combined with resistance exercise training (RET) on skeletal muscle in middle-aged mice consuming a high-fat diet (HFD). Nine-month-old C57BL/6 mice were randomly assigned into four experimental groups (H, high-fat diet; HE, H + RET; HCN, H + CLA/n-3; and HECN, H + CLA/n3 + RET). Body composition and functional capacity were assessed pre- and post-intervention. Muscle tissues were collected at 14 months of age. ANOVA was used, with significance set at P ≤ 0.05. Fat mass significantly increased in H (+74%), HE (+142%) and HECN (+43%) but not in HCN. Muscle wet weights were significantly lower in H and HCN than in HE and HECN. Grip strength substantially declined in H (-15%) and HCN (-17%), whereas sensorimotor function significantly declined only in H (-11%). HECN exhibited improvement in strength (+22%) and sensorimotor coordination (+17%). In comparison to H, muscle tumour necrosis factor-α mRNA expression was significantly lower in HE (-39%), HCN (-24%) and HECN (-21%), respectively. Mean myofibre cross-sectional areas were markedly lower in H and HCN than in HE and HECN. H showed significantly lower satellite cell abundance and numbers of myonuclei than all other groups. Our findings suggest that long-term daily CLA/n-3 intake with resistance training improved sensorimotor function, ameliorated fat gain and prevented loss of myogenic capacity while lowering tumour necrosis factor-α expression during chronic HFD.

Effects of conjugated linoleic acid/n-3 and resistance training on muscle quality and expression of atrophy-related ubiquitin ligases in middle-aged mice with high-fat diet-induced obesity

PURPOSE

To investigate the effects of conjugated linoleic acid (CLA)/n-3 supplements and resistance exercise training (RT) for 20 weeks on muscle quality and genes related to protein synthesis/degradation in middle-aged mice with high-fat diet (HFD)-induced obesity.

METHODS

Nine-month-old C57BL/6 male mice were randomly assigned to five groups: 1) normal diet (C), 2) high-fat diet (H), 3) H+RT (HRT), 4) H+CLA/n-3 (H-CN), and 5) H+RT+CLA/n-3 (H-RTCN). HFD groups were given a diet containing 60% fat for 20 weeks, and exercised groups underwent progressive RT using weighted ladder climbing. The CLA/n-3 mixed diet contained 1% CLA and 1% n-3. Grip strength was assessed, and triceps were removed. RT-PCR was used to analyze transcript levels.

RESULTS

Grip strength of the H group was significantly lower than that of the C group; however, those in the H-CN, H-RT, and H-RTN groups were significantly greater than that in the H group. However, the muscle quality was significantly greater only in the H-RT group compared with the H and H-CN groups. Akt expression decreased in the H-CN, H-RT, and H-RTCN groups compared with those in the C and H groups, whereas mammalian target of rapamycin expression increased in the H, H-CN, H-RT, and H-RTCN groups compared with that in the C group. However, atrogin1 was significantly downregulated in the H-RTCN group compared with that in the H and H-CN groups, and MuRF1 expression was also decreased in the H-RT and H-RTCN groups. Interestingly, atrogin1 and MuRF1 were downregulated in the H-RTCN group compared with that in the H-CN group.

CONCLUSION

HFD-mediated gene expression involved in protein degradation was attenuated following 20-week RT with CLA/n-3. Furthermore, RT with or without CLA/n-3 improved grip strength and muscle quality in middle-aged mice during HFD. Therefore, RT with CLA/n-3 during HFD may improve muscle strength and quality by suppressing protein degradation.

ENabling Reduction of Low-grade Inflammation in SEniors Pilot Study: Concept, Rationale, and Design

OBJECTIVES

To test two interventions to reduce interleukin (IL)-6 levels, an indicator of low-grade chronic inflammation and an independent risk factor for impaired mobility and slow walking speed in older adults.

DESIGN

The ENabling Reduction of low-Grade Inflammation in SEniors (ENRGISE) Pilot Study was a multicenter, double-blind, placebo-controlled randomized pilot trial of two interventions to reduce IL-6 levels.

SETTING

Five university-based research centers.

PARTICIPANTS

Target enrollment was 300 men and women aged 70 and older with an average plasma IL-6 level between 2.5 and 30 pg/mL measured twice at least 1 week apart. Participants had low to moderate physical function, defined as self-reported difficulty walking one-quarter of a mile or climbing a flight of stairs and usual walk speed of less than 1 m/s on a 4-m usual-pace walk.

INTERVENTION

Participants were randomized to losartan, omega-3 fish oil (ω-3), combined losartan and ω-3, or placebo. Randomization was stratified depending on eligibility for each group. A titration schedule was implemented to reach a dose that was safe and effective for IL-6 reduction. Maximal doses were 100 mg/d for losartan and 2.8 g/d for ω-3.

MEASUREMENTS

IL-6, walking speed over 400 m, physical function (Short Physical Performance Battery), other inflammatory markers, safety, tolerability, frailty domains, and maximal leg strength were measured.

RESULTS

Results from the ENRGISE Pilot Study will provide recruitment yields, feasibility, medication tolerance and adherence, and preliminary data to help justify a sample size for a more definitive randomized trial.

CONCLUSION

The ENRGISE Pilot Study will inform a larger subsequent trial that is expected to have important clinical and public health implications for the growing population of older adults with low-grade chronic inflammation and mobility limitations.

Does nutrition play a role in the prevention and management of sarcopenia?

There is a growing body of evidence that links nutrition to muscle mass, strength and function in older adults, suggesting that it has an important role to play both in the prevention and management of sarcopenia. This review summarises the discussions of a working group [ESCEO working group meeting 8th September 2016] that met to review current evidence and to consider its implications for preventive and treatment strategies. The review points to the importance of 'healthier' dietary patterns that are adequate in quality in older age, to ensure sufficient intakes of protein, vitamin D, antioxidant nutrients and long-chain polyunsaturated fatty acids. In particular, there is substantial evidence to support the roles of dietary protein and physical activity as key anabolic stimuli for muscle protein synthesis. However, much of the evidence is observational and from high-income countries. Further high-quality trials, particularly from more diverse populations, are needed to enable an understanding of dose and duration effects of individual nutrients on function, to elucidate mechanistic links, and to define optimal profiles and patterns of nutrient intake for older adults.

A whey protein-based multi-ingredient nutritional supplement stimulates gains in lean body mass and strength in healthy older men: A randomized controlled trial

Protein and other compounds can exert anabolic effects on skeletal muscle, particularly in conjunction with exercise. The objective of this study was to evaluate the efficacy of twice daily consumption of a protein-based, multi-ingredient nutritional supplement to increase strength and lean mass independent of, and in combination with, exercise in healthy older men. Forty-nine healthy older men (age: 73 ± 1 years [mean ± SEM]; BMI: 28.5 ± 1.5 kg/m²) were randomly allocated to 20 weeks of twice daily consumption of either a nutritional supplement (SUPP; n = 25; 30 g whey protein, 2.5 g creatine, 500 IU vitamin D, 400 mg calcium, and 1500 mg n-3 PUFA with 700 mg as eicosapentanoic acid and 445 mg as docosahexanoic acid); or a control (n = 24; CON; 22 g of maltodextrin). The study had two phases. Phase 1 was 6 weeks of SUPP or CON alone. Phase 2 was a 12 week continuation of the SUPP/CON but in combination with exercise: SUPP + EX or CON + EX. Isotonic strength (one repetition maximum [1RM]) and lean body mass (LBM) were the primary outcomes. In Phase 1 only the SUPP group gained strength (Σ1RM, SUPP: +14 ± 4 kg, CON: +3 ± 2 kg, P < 0.001) and lean mass (LBM, +1.2 ± 0.3 kg, CON: -0.1 ± 0.2 kg, P < 0.001). Although both groups gained strength during Phase 2, upon completion of the study upper body strength was greater in the SUPP group compared to the CON group (Σ upper body 1RM: 119 ± 4 vs. 109 ± 5 kg, P = 0.039). We conclude that twice daily consumption of a multi-ingredient nutritional supplement increased muscle strength and lean mass in older men. Increases in strength were enhanced further with exercise training.

Trial Registration: ClinicalTrials.gov NCT02281331

Lower limb explosive strength capacity in elderly women: effects of resistance training and healthy diet

The effects of 24 wk of resistance training combined with a healthy diet on lower limb explosive strength capacity were investigated in a population of healthy elderly women. Participants ( n = 63; 67.5 ± 0.4 yr) were randomized into three groups; resistance training (RT), resistance training and healthy diet (RT-HD), and control (CON). Progressive resistance training was performed at a load of 75–85% one-repetition maximum. A major adjustment in the healthy dietary approach was an n-6/n-3 polyunsaturated fatty acid (PUFA) ratio below 2. Lower limb maximal strength, explosive force capacity during dynamic and isometric movements, whole body lean mass, and physical function were assessed. Whole body lean mass significantly increased by 1.5 ± 0.5% in RT-HD only. Isometric strength performance during knee extension as well as the performance in the five sit-to-stand and single-leg-stance tests increased similarly in RT and RT-HD. Improvements in dynamic peak power and time to reach peak power (i.e shorter time) during knee extension occurred in both RT (+15.7 ± 2.6 and −11.0 ± 3.8%, respectively) and RT-HD (+24.6 ± 2.6 and −20.3 ± 2.7%, respectively); however, changes were significantly larger in RT-HD. Similarly, changes in peak force and rate of force development during squat jump were higher in RT-HD (+58.5 ± 8.4 and +185.4 ± 32.9%, respectively) compared with RT (+35.7 ± 6.9 and +105.4 ± 22.4%, respectively). In conclusion, a healthy diet rich in n-3 PUFA can optimize the effects of resistance training on dynamic explosive strength capacity during isolated lower limb movements and multijoint exercises in healthy elderly women.

NEW & NOTEWORTHY Age-related decline in lower limb explosive strength leads to impaired ability to perform daily living tasks. The present randomized controlled trial demonstrates that a healthy diet rich in n-3 polyunsaturated fatty acid (n-3 PUFA) enhances resistance training-induced gains in dynamic explosive strength capacity during isolated lower limb movements and multijoint exercises in healthy elderly women. This supports the use of strategies combining resistance training and dietary changes to mitigate the decline in explosive strength capacity in older adults.

Preserving Healthy Muscle during Weight Loss

Weight loss is the cornerstone of therapy for people with obesity because it can ameliorate or completely resolve the metabolic risk factors for diabetes, coronary artery disease, and obesity-associated cancers. The potential health benefits of diet-induced weight loss are thought to be compromised by the weight-loss-associated loss of lean body mass, which could increase the risk of sarcopenia (low muscle mass and impaired muscle function). The objective of this review is to provide an overview of what is known about weight-loss-induced muscle loss and its implications for overall physical function (e.g., ability to lift items, walk, and climb stairs). The currently available data in the literature show the following: 1) compared with persons with normal weight, those with obesity have more muscle mass but poor muscle quality; 2) diet-induced weight loss reduces muscle mass without adversely affecting muscle strength; 3) weight loss improves global physical function, most likely because of reduced fat mass; 4) high protein intake helps preserve lean body and muscle mass during weight loss but does not improve muscle strength and could have adverse effects on metabolic function; 5) both endurance- and resistance-type exercise help preserve muscle mass during weight loss, and resistance-type exercise also improves muscle strength. We therefore conclude that weight-loss therapy, including a hypocaloric diet with adequate (but not excessive) protein intake and increased physical activity (particularly resistance-type exercise), should be promoted to maintain muscle mass and improve muscle strength and physical function in persons with obesity.

Intake of Marine-Derived Omega-3 Polyunsaturated Fatty Acids and Mortality in Renal Transplant Recipients

The effect of marine-derived omega-3 polyunsaturated fatty acids (n-3 PUFA) on long-term outcome in renal transplant recipients (RTR) remains unclear. We investigated whether marine-derived n-3 PUFA intake is associated with all-cause and cardiovascular (CV) mortality in RTR. Intake of eicosapentaenoic acid plus docosahexaenoic acid (EPA-DHA) was assessed using a validated Food Frequency Questionnaire. Cox regression analyses were performed to evaluate the associations of EPA-DHA intake with all-cause and CV mortality. We included 627 RTR (age 53 ± 13 years). EPA-DHA intake was 102 (42–215) mg/day. During median follow-up of 5.4 years, 130 (21%) RTR died, with 52 (8.3%) due to CV causes. EPA-DHA intake was associated with lower risk of all-cause mortality (Hazard Ratio (HR) 0.85; 95% confidence interval (95% CI) 0.75–0.97). Age (p= 0.03) and smoking status (p = 0.01) significantly modified this association, with lower risk of all-cause and CV mortality particularly in older (HR 0.75, 95% CI 0.61–0.92; HR 0.68, 95% CI 0.48–0.95) and non-smoking RTR (HR 0.80, 95% CI 0.68–0.93; HR 0.74, 95% CI 0.56–0.98). In conclusion, marine-derived n-3 PUFA intake is inversely associated with risk of all-cause and CV mortality in RTR. The strongest associations were present in subgroups of patients, which adds further evidence to the plea for EPA-DHA supplementation, particularly in elderly and non-smoking RTR.

"Nutraceuticals" in relation to human skeletal muscle and exercise

Skeletal muscles have a fundamental role in locomotion and whole body metabolism, with muscle mass and quality being linked to improved health and even lifespan. Optimizing nutrition in combination with exercise is considered an established, effective ergogenic practice for athletic performance. Importantly, exercise and nutritional approaches also remain arguably the most effective countermeasure for muscle dysfunction associated with aging and numerous clinical conditions, e.g., cancer cachexia, COPD, and organ failure, via engendering favorable adaptations such as increased muscle mass and oxidative capacity. Therefore, it is important to consider the effects of established and novel effectors of muscle mass, function, and metabolism in relation to nutrition and exercise. To address this gap, in this review, we detail existing evidence surrounding the efficacy of a nonexhaustive list of macronutrient, micronutrient, and "nutraceutical" compounds alone and in combination with exercise in relation to skeletal muscle mass, metabolism (protein and fuel), and exercise performance (i.e., strength and endurance capacity). It has long been established that macronutrients have specific roles and impact upon protein metabolism and exercise performance, (i.e., protein positively influences muscle mass and protein metabolism), whereas carbohydrate and fat intakes can influence fuel metabolism and exercise performance. Regarding novel nutraceuticals, we show that the following ones in particular may have effects in relation to 1) muscle mass/protein metabolism: leucine, hydroxyl β-methylbutyrate, creatine, vitamin-D, ursolic acid, and phosphatidic acid; and 2) exercise performance: (i.e., strength or endurance capacity): hydroxyl β-methylbutyrate, carnitine, creatine, nitrates, and β-alanine.

Influence of omega-3 fatty acids on skeletal muscle protein metabolism and mitochondrial bioenergetics in older adults

Omega-3 polyunsaturated fatty acids (n3-PUFA) are recognized for their anti-inflammatory effects and may be beneficial in the context of sarcopenia. We determined the influence of n3-PUFA on muscle mitochondrial physiology and protein metabolism in older adults. Twelve young (18-35 years) and older (65-85 years) men and women were studied at baseline. Older adults were studied again following n3-PUFA supplementation (3.9g/day, 16 weeks). Muscle biopsies were used to evaluate respiratory capacity (high resolution respirometry) and oxidant emissions (spectrofluorometry) in isolated mitochondria. Maximal respiration was significantly lower in older compared to young. n3-PUFA did not change respiration, but significantly reduced oxidant emissions. Participants performed a single bout of resistance exercise, followed by biopsies at 15 and 18 hours post exercise. Several genes involved in muscle protein turnover were significantly altered in older adults at baseline and following exercise, yet muscle protein synthesis was similar between age groups under both conditions. Following n3-PUFA supplementation, mixed muscle, mitochondrial, and sarcoplasmic protein synthesis rates were increased in older adults before exercise. n3-PUFA increased post-exercise mitochondrial and myofibrillar protein synthesis in older adults. These results demonstrate that n3-PUFA reduce mitochondrial oxidant emissions, increase postabsorptive muscle protein synthesis, and enhance anabolic responses to exercise in older adults.

Therapy and Rehabilitation for Upper Extremity Injuries in Athletes

The approach to rehabilitation of upper extremity injuries in athletes differs from traditional rehabilitation protocols. In general, athletes have higher functional demands and wish to return to competitive sport in a timely manner. Comprehensive rehabilitation must therefore be balanced with a timely and safe return to sport. Several rehabilitation programs and adjunctive therapies are available to hasten convalescence while minimizing the athlete's risks of reinjury. Here, we review techniques for soft tissue mobilization and strength training in athletic populations. We also discuss orthotics, taping, and alternative therapies used in rehabilitation and evaluate the evidence in support of these modalities.

Dietary Variety and Decline in Lean Mass and Physical Performance in Community-Dwelling Older Japanese: A 4-year Follow-Up Study

OBJECTIVES

To examine associations of dietary variety with changes in lean mass and physical performance during a 4-year period in an elderly Japanese population.

DESIGN

Four-year prospective study.

SETTING

The Hatoyama Cohort Study and Kusatsu Longitudinal Study, Japan.

PARTICIPANTS

935 community-dwelling Japanese aged 65 years or older.

MEASUREMENTS

Dietary variety was assessed using a 10-item food frequency questionnaire. Body composition was determined by multifrequency bioelectrical impedance analysis, and physical performance (grip strength and usual gait speed) was measured in surveys at baseline and 4 years later. Longitudinal analysis included only participants who were originally in the upper three quartiles of lean body mass, appendicular lean mass, grip strength, and usual gait speed. The outcome measures were decline in lean body mass, appendicular lean mass, grip strength, and usual gait speed, defined as a decrease to the lowest baseline quartile level at the 4-year follow-up survey. Associations of dietary variety with the outcome measures were examined by logistic regression analysis adjusted for potential confounders.

RESULTS

In the fully adjusted model, the odds ratios for decline in grip strength and usual gait speed were 0.43 (95% confidence interval, 0.19-0.99) and 0.43 (confidence interval, 0.19-0.99), respectively, for participants in the highest category of dietary variety score as compared with those in the lowest category. Dietary variety was not significantly associated with changes in lean body mass or appendicular lean mass.

CONCLUSION

Among older adults, greater dietary variety may help maintain physical performance, such as grip strength and usual gait speed, but not lean mass.

Sex differences in the effect of fish-oil supplementation on the adaptive response to resistance exercise training in older people: a randomized controlled trial

BACKGROUND

Resistance exercise increases muscle mass and function in older adults, but responses are attenuated compared with younger people. Data suggest that long-chain n-3 polyunsaturated fatty acids (PUFAs) may enhance adaptations to resistance exercise in older women. To our knowledge, this possibility has not been investigated in men.

OBJECTIVE

We sought to determine the effects of long-chain n-3 PUFA supplementation on resistance exercise training-induced increases in muscle mass and function and whether these effects differ between older men and women.

DESIGN

Fifty men and women [men: n = 27, mean ± SD age: 70.6 ± 4.5 y, mean ± SD body mass index (BMI; in kg/m2): 25.6 ± 4.2; women: n = 23, mean ± SD age: 70.7 ± 3.3 y, mean ± SD BMI: 25.3 ± 4.7] were randomly assigned to either long-chain n-3 PUFA (n = 23; 3 g fish oil/d) or placebo (n = 27; 3 g safflower oil/d) and participated in lower-limb resistance exercise training twice weekly for 18 wk. Muscle size, strength, and quality (strength per unit muscle area), functional abilities, and circulating metabolic and inflammatory markers were measured before and after the intervention.

RESULTS

Maximal isometric torque increased after exercise training to a greater (P < 0.05) extent in the long-chain n-3 PUFA group than in the placebo group in women, with no differences (P > 0.05) between groups in men. In both sexes, the effect of exercise training on maximal isokinetic torque at 30, 90, and 240° s-1, 4-m walk time, chair-rise time, muscle anatomic cross-sectional area, and muscle fat did not differ (P > 0.05) between groups. There was a greater (P < 0.05) increase in muscle quality in women after exercise training in the long-chain n-3 PUFA group than in the placebo group, with no such differences in men (P > 0.05). Long-chain n-3 PUFAs resulted in a greater decrease (P < 0.05) than the placebo in plasma triglyceride concentrations in both sexes, with no differences (P > 0.05) in glucose, insulin, or inflammatory markers.

CONCLUSION

Long-chain n-3 PUFA supplementation augments increases in muscle function and quality in older women but not in older men after resistance exercise training. This trial was registered at clinicaltrials.gov as NCT02843009.

Lipids and physical function in older adults

PURPOSE OF REVIEW

Healthy aging is a public health priority. The maintenance of adequate physical function is recognized as a key element of healthy aging. In recent years, scientific evidence has increased concerning the ability of lipids, in particular omega 3 polyunsaturated fatty acids (n-3 PUFAs), to positively influence muscle and overall physical function in older patients. The article will critically review observational as well as intervention studies on this topic, and it will elucidate the potential biological mechanisms underlying the beneficial effects of n-3 PUFA on physical function.

RECENT FINDINGS

Observational studies and clinical trials performed in healthy older patients and in older patients with chronic diseases mostly found positive effects of n-3 PUFA on muscle metabolism, muscle strength and in general physical function.

SUMMARY

Although the use of n-3 PUFA might represent an important intervention to preserve physical function in older adults, several key questions still need to be answered. Above all, large randomized controlled trials should be performed to confirm the utility of n-3 PUFA as therapeutic agents to prevent and treat physical function decline in old age.

Fit with good fat? The role of n-3 polyunsaturated fatty acids on exercise performance

N-3 PUFA (n-3) polyunsaturated fatty acids (PUFA) are a family of fatty acids mainly found in oily fish and fish oil supplements. The effects of n-3 PUFA on health are mainly derived from its anti-inflammatory proprieties and its influence on immune function. Lately an increased interest in n-3 PUFA supplementation has reached the world of sport nutrition, where the majority of athletes rely on nutrition strategies to improve their training and performance. A vast amount of attention is paid in increasing metabolic capacity, delaying the onset of fatigue, and improving muscle hypertrophy and neuromuscular function. Nutritional strategies are also frequently considered for enhancing recovery, improving immune function and decreasing oxidative stress. The current review of the literature shows that data regarding the effects of n-3PUFA supplementation are conflicting and we conclude that there is, therefore, not enough evidence supporting a beneficial role on the aforementioned aspects of exercise performance.

Effects of Almond- and Olive Oil-Based Docosahexaenoic- and Vitamin E-Enriched Beverage Dietary Supplementation on Inflammation Associated to Exercise and Age

n-3-polyunsaturated fatty acids and polyphenols are potential key factors for the treatment and prevention of chronic inflammation associated to ageing and non-communicable diseases. The aim was to analyse effects of an almond and olive oil beverage enriched with α-tocopherol and docosahexaenoic, exercise and age on inflammatory plasma markers, and immune gene expression in peripheral blood mononuclear cells (PBMCs). Five young and five senior athletes who were supplemented for five weeks with a functional beverage performed a stress test under controlled conditions before and after beverage supplementation. Blood samples were taken immediately before and 1 h after each test. Plasma, erythrocytes and PBMCs were isolated. Beverage supplementation increased plasmatic Tumour Necrosis Factor α (TNFα) levels depending on age and exercise. Exercise increased plasma non esterified fatty acids (NEFAs), soluble Intercellular adhesion molecule 3 (sICAM3) and soluble L-selectin (sL-Selectin), and this increase was attenuated by the supplementation. Exercise increased PGE2 plasma levels in supplemented young and in senior placebo athletes. Exercise increased NFkβ-activated levels in PBMCs, which are primed to a pro-inflammatory response increasing pro-inflammatory genes expression after the exercise mainly in the young group after the supplementation. The functional beverage supplementation to young athletes enhances a pro-inflammatory circulating environment in response to the exercise that was less evident in the senior group.

Effect of dietary n-3 PUFA supplementation on the muscle transcriptome in older adults

Dietary fish oil-derived n-3 PUFA supplementation can increase muscle mass, reduce oxygen demand during physical activity, and improve physical function (muscle strength and power, and endurance) in people. The results from several studies conducted in animals suggest that the anabolic and performance-enhancing effects of n-3 PUFA are at least in part transcriptionally regulated. The effect of n-3 PUFA therapy on the muscle transcriptome in people is unknown. In this study, we used muscle biopsy samples collected during a recently completed randomized controlled trial that found that n-3 PUFA therapy increased muscle mass and function in older adults to provide a comprehensive assessment of the effect of n-3 PUFA therapy on the skeletal muscle gene expression profile in these people. Using the microarray technique, we found that several pathways involved in regulating mitochondrial function and extracellular matrix organization were increased and pathways related to calpain- and ubiquitin-mediated proteolysis and inhibition of the key anabolic regulator mTOR were decreased by n-3 PUFA therapy. However, the effect of n-3 PUFA therapy on the expression of individual genes involved in regulating mitochondrial function and muscle growth, assessed by quantitative RT-PCR, was very small. These data suggest that n-3 PUFA therapy results in small but coordinated changes in the muscle transcriptome that may help explain the n-3 PUFA-induced improvements in muscle mass and function.

Fish oil supplementation suppresses resistance exercise and feeding-induced increases in anabolic signaling without affecting myofibrillar protein synthesis in young men

Fish oil (FO) supplementation potentiates muscle protein synthesis (MPS) in response to a hyperaminoacidemic-hyperinsulinemic infusion. Whether FO supplementation potentiates MPS in response to protein ingestion or when protein ingestion is combined with resistance exercise (RE) remains unknown. In a randomized, parallel group design, 20 healthy males were randomized to receive 5 g/day of either FO or coconut oil control (CO) for 8 weeks. After supplementation, participants performed a bout of unilateral RE followed by ingestion of 30 g of whey protein. Skeletal muscle biopsies were obtained before and after supplementation for assessment of muscle lipid composition and relevant protein kinase activities. Infusion of L-[ring-(13)C6] phenylalanine was used to measure basal myofibrillar MP Sat rest (REST), in a nonexercised leg following protein ingestion (FED) and following RE and protein ingestion (FEDEX).MPS was significantly elevated above REST during FEDEX in both the FO and CO groups, but there was no effect of supplementation. There was a significant increase in MPS in both groups above REST during FED but no effect of supplementation. Supplementation significantly decreased pan PKB activity at RESTin the FO group but not the CO group. There was a significant increase from REST at post-RE for PKB and AMPKα2 activity in the CO group but not in the FO group. In FEDEX, there was a significant increase in p70S6K1 activity from REST at 3 h in the CO group only. These data highlight that 8 weeks of FO supplementation alters kinase signaling activity in response to RE plus protein ingestion without influencing MPS.

Eicosapentaenoic and Docosahexaenoic Acid-Enriched High Fat Diet Delays Skeletal Muscle Degradation in Mice

Low-grade chronic inflammatory conditions such as ageing, obesity and related metabolic disorders are associated with deterioration of skeletal muscle (SkM). Human studies have shown that marine fatty acids influence SkM function, though the underlying mechanisms of action are unknown. As a model of diet-induced obesity, we fed C57BL/6J mice either a high fat diet (HFD) with purified marine fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (HFD-ED), a HFD with corn oil, or normal mouse chow for 8 weeks; and used transcriptomics to identify the molecular effects of EPA and DHA on SkM. Consumption of ED-enriched HFD modulated SkM metabolism through increased gene expression of mitochondrial β-oxidation and slow-fiber type genes compared with HFD-corn oil fed mice. Furthermore, HFD-ED intake increased nuclear localization of nuclear factor of activated T-cells (Nfatc4) protein, which controls fiber-type composition. This data suggests a role for EPA and DHA in mitigating some of the molecular responses due to a HFD in SkM. Overall, the results suggest that increased consumption of the marine fatty acids EPA and DHA may aid in the prevention of molecular processes that lead to muscle deterioration commonly associated with obesity-induced low-grade inflammation.

Sarcopenia in Patients with Chronic Liver Disease: Can It Be Altered by Diet and Exercise?

Sarcopenia, a loss of muscle mass, is being increasingly recognized to have a deleterious effect on outcomes in patients with chronic liver disease. Factors related to diet and the inflammatory nature of chronic liver disease contribute to the occurrence of sarcopenia in these patients. Sarcopenia adversely influences quality of life, performance, morbidity, success of transplantation, and even mortality. Specific deficiencies in macronutrients (protein, polyunsaturated fatty acids) and micronutrients (vitamins C, D, and E, carotenoids, and selenium) have been linked to sarcopenia. Lessons learned from nutritional therapy in geriatric patient populations may provide strategies to manage sarcopenia in patients with liver disease. Combining diet modification and nutrient supplementation with an organized program of exercise may help ameliorate or even reverse the effects of sarcopenia on an already complex disease process.

High Dose Omega-3 Fatty Acid Administration and Skeletal Muscle Protein Turnover in Maintenance Hemodialysis Patients

BACKGROUND AND OBJECTIVES

Protein energy wasting and systemic inflammation are prevalent in maintenance hemodialysis (MHD) patients. Omega-3 (ω-3) fatty acids have anti-inflammatory properties and have been shown to improve protein homeostasis. We hypothesized that administration of high-dose (2.9 g/d) ω-3 would be associated with decreased muscle protein breakdown in MHD patients with systemic inflammation.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

This is a substudy from a randomized, placebo-controlled study (NCT00655525). Patients were recruited between September 2008 and June 2011. Primary inclusion criteria included signs of chronic inflammation (average C-reactive protein of ≥5 mg/L over three consecutive measurements), lack of active infectious or inflammatory disease, no hospitalization within 1 month prior to the study, and not receiving steroids (>5 mg/d) and/or immunosuppressive agents. The primary outcomes were forearm muscle and whole body protein breakdown and synthesis before and after the intervention. The patients received ω-3 (n=11) versus placebo (n=9) for 12 weeks. Analysis of covariance was used to compare outcome variables at 12 weeks. Models were adjusted for a propensity score that was derived from age, sex, race, baseline high sensitivity C-reactive protein, diabetes mellitus, and fat mass because the groups were not balanced for several characteristics.

RESULTS

Compared with placebo, ω-3 supplementation was significantly associated with decreased muscle protein breakdown at 12 weeks (-31, [interquartile range, -98--13] versus 26 [interquartile range, 13-87] µg/100 ml per min; P=0.01), which remained significant after multivariate adjustment (-46, [95% confidence interval, -102 to -1] µg/100 ml per min). ω-3 Supplementation resulted in decreased forearm muscle protein synthesis while the rate in the placebo group increased; however, there is no longer a statistically significant difference in skeletal muscle protein synthesis or in net protein balance after multivariate adjustment. There was no statistically significant effect of ω-3 supplementation on whole body protein synthesis or breakdown.

CONCLUSIONS

High-dose ω-3 supplementation over 12 weeks in MHD patients with systemic inflammation was associated with attenuation of forearm muscle protein breakdown but did not influence skeletal muscle protein synthesis, skeletal muscle net protein balance or any component of the whole-body protein balance. These results should be interpreted cautiously given the imbalance in the two groups and the short duration of the intervention.

The Effects of Dietary Omega-3s on Muscle Composition and Quality in Older Adults

This review will focus on findings from the few studies performed to date in humans to examine changes in muscle protein turnover, lean or muscle mass and physical function following fish oil-derived omega-3 fatty acid treatment. Although considerable gaps in our current knowledge exist, hypertrophic responses (e.g., improvements in the rate of muscle protein synthesis and mTOR signaling during increased amino acid availability and an increase in muscle volume) have been reported in older adults following prolonged (8 to 24 weeks) of omega-3 fatty acid supplementation. There is also accumulating evidence that increased omega-3 fatty acid levels in red blood cells are positively related to strength and measures of physical function. As a result, increased omega-3 fatty acid consumption may prove to be a promising low-cost dietary approach to attenuate or prevent aging associated declines in muscle mass and function.