Omega-3 (n-3) polyunsaturated fatty acid (PUFA) supplementation has recently been proposed as an ergogenic aid for athletes. This claim is primarily based on mechanistic evidence that n-3PUFA's exert anti-inflammatory properties and act to change the functional capacity of the muscle cell by modifying the membrane fluidity of proteins and lipids within the cell membrane. In this review, we critically evaluate the scientific literature that examines the efficacy of n-3PUFA supplementation to improve athlete performance within the context of promoting muscle adaptation, energy metabolism, muscle recovery and injury prevention (e.g. muscle loss during immobilisation, concussion). These findings have applications to athletes competing in strength/power-, endurance-and team-, based sports. Based on available information, there is promising scientific evidence that n-3PUFA supplementation may improve endurance capacity by reducing the oxygen cost of exercise. Moreover, several studies report a benefit of n-3PUFA supplementation in promoting recovery from eccentric-based muscle damaging exercise. In contrast, there is insufficient evidence from studies in athletic populations to support the claim that n-3PUFA supplementation facilitates muscle growth during resistance training or preserves muscle mass during catabolic scenarios such as energy restriction or immobilisation. Moving forward, there remains ample scope to investigate context-specific applications of n-3PUFA supplementation for sport performance.

Soccer players often experience eccentric exercise-induced muscle damage given the physical demands of soccer match-play. Since long chain n-3 polyunsaturated fatty acids (n-3PUFA) enhance muscle sensitivity to protein supplementation, dietary supplementation with a combination of fish oil-derived n-3PUFA, protein and carbohydrate may promote exercise recovery. This study examined the influence of adding n-3PUFA to a whey protein, leucine and carbohydrate containing beverage over a 6 week supplementation period on physiological markers of recovery measured over 3 days following eccentric exercise. Competitive soccer players were assigned to one of three conditions (2 × 200mL): FO (n=10) contained n-3PUFA (1100mg DHA/EPA -approx. 550mg DHA, 550mg EPA), whey protein (15g), leucine (1.8g) and carbohydrate (20g); PRO (n=10) contained whey protein (15g), leucine (1.8g) and carbohydrate (20g) and CHO (n=10) contained carbohydrate (24g). Eccentric exercise consisted of unilateral knee extension/flexion contractions on both legs separately. Maximal force production was impaired by 22% during the 72 hour recovery period following eccentric exercise (p<0.05). Muscle soreness, expressed as AUC during 72 hour recovery, was less in FO (1948±1091 mm×72 h) than PRO (4640±2654 mm×72h, p<0.05) and CHO (4495±1853 mm×72h p=0.10). Blood concentrations of creatine kinase, expressed as AUC, were ~60% lower in FO compared to CHO (p<0.05) and tended to be lower (~39%, p = 0.07) than PRO.No differences in muscle function, soccer performance or blood c-reactive protein concentrations were observed between groups. In conclusion, the addition of n-3PUFA to a beverage containing whey protein, leucine and carbohydrate ameliorates the increase in muscle soreness and blood concentrations of creatine kinase following eccentric exercise in competitive soccer players.

Background: A detrimental consequence of diet-induced weight loss, common in athletes who participate in weight cutting sports, is muscle loss. Dietary omega-3 polyunsaturated fatty acids (n-3PUFA) exhibit a protective effect on the loss of muscle tissue during catabolic situations such as injury-simulated leg immobilization. This study aimed to investigate the influence of dietary n-3PUFA supplementation on changes in body composition and muscle strength following short-term diet-induced weight loss in resistance-trained men. Methods: Twenty resistance-trained young (23 ± 1 years) men were randomly assigned to a fish oil group that supplemented their diet with 4 g n-3PUFA, 18 g carbohydrate, and 5 g protein (FO) or placebo group containing an equivalent carbohydrate and protein content (CON) over a 6 week period. During weeks 1–3, participants continued their habitual diet. During week 4, participants received all food items to control energy balance and a macronutrient composition of 50% carbohydrate, 35% fat, and 15% protein. During weeks 5 and 6, participants were fed an energy-restricted diet equivalent to 60% habitual energy intake. Body composition and strength were measured during weeks 1, 4, and 6. Results: The decline in total body mass (FO = −3.0 ± 0.3 kg, CON = −2.6 ± 0.3 kg), fat free mass (FO = −1.4 ± 0.3 kg, CON = −1.2 ± 0.3 kg) and fat mass (FO = −1.4 ± 0.2 kg, CON = −1.3 ± 0.3 kg) following energy restriction was similar between groups (all p > 0.05; d: 0.16–0.39). Non-dominant leg extension 1 RM increased (6.1 ± 3.4%) following energy restriction in FO ( p < 0.05, d = 0.29), with no changes observed in CON ( p > 0.05, d = 0.05). Dominant leg extension 1 RM tended to increase following energy restriction in FO ( p = 0.09, d = 0.29), with no changes in CON ( p > 0.05, d = 0.06). Changes in leg press 1 RM, maximum voluntary contraction and muscular endurance following energy restriction were similar between groups ( p > 0.05, d = 0.05). Conclusion: Any possible improvements in muscle strength during short-term weight loss with n-3PUFA supplementation are not related to the modulation of FFM in resistance-trained men.

Resident tissue macrophages (RTMs) develop from distinct waves of embryonic progenitor cells that seed tissues before birth. Tissuespecific signals drive a differentiation program that leads to the functional specialization of RTM subsets. Genetic programs that regulate the development of RTMs are incompletely understood, as are the mechanisms that enable their maintenance in adulthood. In this study, we show that the ligand-activated nuclear hormone receptor, retinoid X receptor (RXR)a, is a key regulator of murine RTM development. Deletion of RXRa in hematopoietic precursors severely curtailed RTM populations in adult tissues, including the spleen, peritoneal cavity, lung, and liver. The deficiency could be traced to the embryonic period, and mice lacking RXRa in hematopoietic lineages had greatly reduced numbers of yolk sac and fetal liver macrophages, a paucity that persisted into the immediate postnatal period. ImmunoHorizons, 2022, 6: 366-372.

RESULTS: Dot blot analyses of exosome-specific proteins (CD9, CD63, and CD81) and TRPS confirmed the presence of isolated exosomes in all samples following SEC elution. Western Blot confirmed the absence of contaminating proteins. Although no differences in exosome concentration were seen following any of the exercise interventions, exosome profiling showed a decrease in exosomes associated with cancer metastasis (MCSP) between pre-(0.029 ± 0.01) and post-intervention (0.017 ± 0.019, p=0.03). The exosome expression of the monocyte and macrophage marker was also reduced from 0.023 ± 0.029 to 0.007 ± 0.019 (p=0.02) post-intervention in all groups. CONCLUSION: This evaluation and validation of methods have shown that exosome isolation, characterization, and profiling can be achieved with minimal volume. Funded by NIH R21AG058181.