The interplay between gut microbiome and physical exercise in athletes.

PURPOSE OF REVIEW: The gut microbiome regulates several health and disease-related processes. However, the potential bidirectional relationship between the gut microbiome and physical exercise remains uncertain. Here, we review the evidence related to the gut microbiome in athletes. RECENT FINDINGS: The effect of physical exercise on the intestinal microbiome and intestinal epithelial cells depends on the type, volume, and intensity of the activity. Strenuous exercise negatively impacts the intestinal microbiome, but adequate training and dietary planning could mitigate these effects. An increase in short-chain fatty acids (SCFAs) concentrations can modulate signaling pathways in skeletal muscle, contributing to greater metabolic efficiency, preserving muscle glycogen, and consequently optimizing physical performance and recovery. Furthermore, higher SCFAs concentrations appear to lower inflammatory response, consequently preventing an exacerbated immune response and reducing the risk of infections among athletes. Regarding dietary interventions, the optimal diet composition for targeting the athlete's microbiome is not yet known. Likewise, the benefits or harms of using probiotics, synbiotics, and postbiotics are not well established, whereas prebiotics appear to optimize SCFAs production. SUMMARY: The intestinal microbiome plays an important role in modulating health, performance, and recovery in athletes. SCFAs appear to be the main intestinal metabolite related to these effects. Nutritional strategies focusing on the intestinal microbiome need to be developed and tested in well controlled clinical trials.

Short-Term Cocoa Supplementation Influences Microbiota Composition and Serum Markers of Lipid Metabolism in Elite Male Soccer Players.

OBJECTIVES: Dietary strategies to improve arachidonic acid:eicosapentaenoic acid (AA:EPA) ratios are of interest due to potential reductions in inflammation and oxidative stress following exercise. The aim of this study was to investigate the impact of a novel dietary intervention, that is, the ingestion of 30 g of dark chocolate, on blood lipid profiles and gut microbiota composition in elite male soccer players. METHODS: Professional male soccer players were randomly assigned to the experimental group (DC) provided with 30 g of dark chocolate or to the control group (WC), provided with 30 g of white chocolate, for 30 days. Before and after intervention, blood, fecal sample, and anthropometry data were collected. For each outcome, two-way repeated-measure analysis of variance was used to identify differences between baseline and endpoint (Week 4), considering treatment (dark chocolate, white chocolate) as intersubjects' factors. Metagenomic analysis was performed following the general guidelines, which relies on the bioBakery computational environment. RESULTS: DC group showed increased plasma polyphenols (from 154.7 ± 18.6 µg gallic acid equivalents/ml to 185.11 ± 57.6 µg gallic acid equivalents/ml, Δ pre vs. post = +30.41 ± 21.50) and significant improvements in lipid profiles: total cholesterol (Δ -32.47 ± 17.18 mg/dl DC vs. Δ -2.84 ± 6.25 mg/dl WC, Time × Treatment interaction p < .001), triglycerides (Δ -6.32 ± 4.96 mg/dl DC vs. Δ -0.42 ± 6.47 mg/dl WC, Time × Treatment interaction p < .001), low-density lipoprotein (Δ -18.42 ± 17.13 mg/dl vs. Δ -2.05 ± 5.19 mg/dl WC, Time × Treatment interaction p < .001), AA/EPA ratio (Δ -5.26 ± 2.35; -54.1% DC vs. Δ -0.47 ± 0.73, -6.41% WC, Time × Treatment interaction p < .001) compared with WC group. In addition, 4 weeks of intervention showed a significant increase in high-density lipoprotein concentration in DC group (Δ + 3.26 ± 4.49 mg/dl DC vs. Δ -0.79 ± 5.12 mg/dl WC). Microbial communities in the DC group maintained a slightly higher microbial stability over time (exhibiting lower within-subject community dissimilarity). CONCLUSION: Ingesting 30 g of dark chocolate over 4 weeks positively improved AA:EPA ratio and maintained gut microbial stability. Dark chocolate ingestion represents an effective nutritional strategy to improve blood lipid profiles in professional soccer players. What Are the Findings? Ingesting 30 g of dark chocolate for 4 weeks positively influences blood lipid AA: EPA ratio while maintaining gut microbial stability. What This Study Adds? Dietary intake of specific foods such as dark chocolate represents an alternative strategy to support the health and recovery of elite soccer players. What Impact Might This Have on Clinical Practice in the Future? From a clinical and translational perspective, dark chocolate ingestion positively modulates favorable blood lipid profiles and polyunsaturated fatty acid metabolism while maintaining gut microbial stability. Dark chocolate ingestion may be considered as an effective nutritional strategy in elite sport environments during periods of high-intensity training and congested competitions. Further research is required to determine functional outcomes associated with the observed improvements in blood lipid profiles.

Cycle ergometer training and resistance training similarly increase muscle strength in trained men.

The aim of this study was to compare two different maximal intensity exercise modality training protocols of similar durations on muscle strength, cardiorespiratory fitness, and lower limb composition in recreationally trained men. Twenty-five trained men (28.9 ± 5.6 years) were randomly divided into Cycle ergometer (4 sets of 30 seconds sprints) and Leg press (4 sets of 10-12 repetitions to momentary failure). Both groups trained three times a week for 5 weeks. Before and after the training period, the participants performed a 10-repetition maximum (10RM) test for knee extension, an incremental exercise test on a treadmill for time to exhaustion (TTE) and peak oxygen consumption (V˙O2peak) and underwent dual energy X-ray absorptiometry to assess lower limb composition. Knee extension 10RM and TTE increased in both groups with no statistically significant between group (p = 0.614 and p = 0.210). Only cycle ergometer group increased V˙O2peak (p = 0,012). For all lower limb composition outcomes, changes were minimal. The results suggest that 5 weeks of effort and duration matched exercise protocols using cycle ergometer training or leg press may produce similar strength adaptations.

Optimizing Microbiota Profiles for Athletes.

Gut microbiome influences athletes' physiology, but because of the complexity of sport performance and the great intervariability of microbiome features, it is not reasonable to define a single healthy microbiota profile for athletes. We suggest the use of specific meta-omics analysis coupled with innovative computational systems to uncover the hidden association between microbes and athlete's physiology and predict personalized recommendation.

Gut microbiota is associated with adiposity markers and probiotics may impact specific genera.

PURPOSE: It has been suggested that restoring gut microbiota alterations with probiotics represents a potential clinical target for the treatment of gut microbiota-related diseases, such as obesity. Here, we apply 16S rDNA microbiota profiling to establish which bacteria in the human gut are associated with obesity and cardiometabolic risk factors, and to evaluate whether probiotic supplementation modulates gut microbiota. METHODS: We evaluated the effects of a probiotic mixture (2 × 1010 CFU/day of Lactobacillus acidophilus LA-14, Lactobacillus casei LC-11, Lactococcus lactis LL-23, Bifidobacterium bifidum BB-06, and Bifidobacterium lactis BL-4) in 32 overweight or obese women in a double-blind, randomized, placebo-controlled study. Using 16S rDNA sequencing, we characterized fecal samples and investigated the relationships between microbiome data and diet, body composition, antioxidant enzymes, and inflammatory profile. In addition, we characterized the degree of variation among fecal communities after the intervention. RESULTS: BMI, weight, fat mass, lean mass, conicity index, protein intake, monounsaturated fat intake, glycated hemoglobin, TNF-α, and IL6/IL10 were significantly correlated with microbiome composition. The candidate division TM7 was strongly associated with all adiposity markers and Clostridiaceae associated negatively with TNF-α. The family Clostridiaceae increased and TM7 tended to decrease after the probiotic mixture supplementation. Subjects were clustered according to body composition, and a higher proportion of TM7 was observed in those with higher adiposity. CONCLUSIONS: Ecosystem-wide analysis of probiotic use effects on the gut microbiota revealed a genera specific influence, and one of which (TM7) represents a promising novel target for obesity treatment. TRIAL REGISTRATION NUMBER: U1111-1137-4566.

Effects of turmeric extract supplementation on inflammation and muscle damage after a half-marathon race: a randomized, double-blind, placebo-controlled trial.

PURPOSE: Strenuous exercise induces inflammation and muscle damage. Turmeric (Curcuma longa L.) is a widely used spice that exhibits potent anti-inflammatory response and appears to decrease indirect markers of muscle damage. A randomized, double-blind, placebo-controlled trial was conducted to evaluate the effects of Curcuma longa L. extract (CLE) on inflammation and muscle damage after a half-marathon race. METHODS: Twenty-eight healthy, normal-weight men were randomly assigned to one of two groups: (1) CLE (3 capsules per day, 500 mg each); or (2) placebo (PLA, 3 capsules per day, 500 mg of microcrystalline cellulose). Participants received the intervention for 4 weeks and immediately before and after the half-marathon race. Creatine kinase, lactate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, myoglobin, interleukins 6 and 10 were assessed at baseline, immediately before, after, and at 2, 24, and 48 h after the half-marathon race. RESULTS: The half-marathon race increased markers of inflammation and muscle damage. A greater increase in interleukin-10 was observed in the CLE group immediately after the competition compared to the PLA group (7.54 ± 1.45 vs 5.25 ± 0.59 pg/mL; p < 0.05; d = 0.55). Myoglobin concentration was lower 2 h after the race in participants from the CLE group compared to the PLA group (62.10 ± 8.26 vs 107.85 ± 18.45 ng/mL; p = 0.01; d = 0.86). CONCLUSION: Curcuma longa L. extract supplementation leads to an increase in IL-10 and decreased myoglobin in recreational male runners after a half-marathon race. TRIAL REGISTRATION NUMBER: U1111-1179-6335, February 13, 2016.

Sodium Bicarbonate Supplementation Does Not Improve Running Anaerobic Sprint Test Performance in Semiprofessional Adolescent Soccer Players.

Ergogenic strategies have been studied to alleviate muscle fatigue and improve sports performance. Sodium bicarbonate (NaHCO3) has improved repeated sprint performance in adult team-sports players, but the effect for adolescents is unknown. The aim of the present study was to evaluate the effect of NaHCO3 supplementation on repeated sprint performance in semiprofessional adolescent soccer players. In a double-blind, placebo-controlled, crossover trial, 15 male semiprofessional adolescent soccer players (15 ± 1 years; body fat 10.7 ± 1.3%) ingested NaHCO3 or a placebo (sodium chloride) 90 min before performing the running anaerobic sprint test (RAST). A countermovement jump was performed before and after the RAST, and ratings of perceived exertion, blood parameters (potential hydrogen and bicarbonate concentration), and fatigue index were also evaluated. Supplementation with NaHCO3 promoted alkalosis, as demonstrated by the increase from the baseline to preexercise, compared with the placebo (potential hydrogen: +0.07 ± 0.01 vs. -0.00 ± 0.01, p < .001 and bicarbonate: +3.44 ± 0.38 vs. -1.45 ± 0.31 mmol/L, p < .001); however, this change did not translate into an improvement in RAST total time (32.12 ± 0.30 vs. 33.31 ± 0.41 s, p = .553); fatigue index (5.44 ± 0.64 vs. 6.28 ± 0.64 W/s, p = .263); ratings of perceived exertion (7.60 ± 0.33 vs. 7.80 ± 0.10 units, p = .525); countermovement jump pre-RAST (32.21 ± 3.35 vs. 32.05 ± 3.51 cm, p = .383); or countermovement jump post-RAST (31.70 ± 0.78 vs. 32.74 ± 1.11 cm, p = .696). Acute NaHCO3 supplementation did not reduce muscle fatigue or improve RAST performance in semiprofessional adolescent soccer players. More work assessing supplementation in this age group is required to increase understanding in the area.

Bioanalytical method by HPLC-FLD for curcumin analysis in supplemented athletes.

In sports, curcumin, a substance derived from the rhizome of Curcuma longa (turmeric) plant with antioxidant effect 8 times greater than vitamin E, has attracted the attention of scientists because of its potent antioxidant action, since in athletes subjected to intense exercise the-endogenous mechanisms of neutralization of reactive species are saturated. However, the pharmacokinetic characteristics of curcumin do not favor its medicinal use due to its low absorption, accelerated metabolism and rapid systemic elimination. Thus, the determination of plasma levels in supplemented patients is a crucial step in their pharmacodynamic evaluation. Therefore, the objective of this work was to develop and validate an analytical method by HPLC-FLD for curcumin evaluation in plasma of supplemented athletes. Luna column (C18; 150 × 4 mm; 3 µm), acetonitrile: acetic acid pH 3.2 (45:55 to 60:40) as mobile phase, flow rate of 1 mL min-1, excitation at 429/285 nm and emission at 529 nm and injection of 10 µL were the chromatographic conditions used. Plasma samples were extracted using ethylacetate and methanol (95: 5, 500 µL) and estradiol (30 µg mL-1) as internal standard, with subsequent stirring (3 min) and centrifugation (8 min) (triple extraction). The organic fraction was evaporated under N2 (20 min) and the dried residue reconstituted in acetonitrile. The method was linear between 44 and 261 ng mL-1, showing intra-day (2.05.6%) and inter-day (4.0-5.1%) precision with accuracy and selectiveness (curcumin tR = 8.7 min and internal standard tR = 13.9 min with relative recovery of 83.2%). So, it can be successfully used for curcumin evaluation in plasma samples from supplemented athletes, as well as being an alternative and advantageous method to UV-Vis and MS/MS in bioavailability studies.

Intradialytic Resistance Training Improves Functional Capacity and Lean Mass Gain in Individuals on Hemodialysis: A Randomized Pilot Trial.

OBJECTIVE: To compare the effects of high vs moderate loads of intradialytic resistance training (RT) on body composition, sarcopenia prevalence, functional capacity, inflammatory markers, and quality of life (QoL) in individuals on hemodialysis. DESIGN: A pilot randomized clinical trial. SETTING: Two hemodialysis centers. PARTICIPANTS: Individuals on hemodialysis (N=80; 51% men, aged 30-75y) in treatment for at least 3 months, adequately dialyzed (Kt/V≥1.2, where K is dialyzer clearance in mL/min, t is time, and V is volume of water) with vascular access via arteriovenous fistula. INTERVENTIONS: The 12 weeks of intradialytic RT was performed 3 times per week. The training groups were: high-load intradialytic group (HLG, 8-10 repetitions), moderate-load intradialytic group (MLG, 16-18 repetitions), and control group (CG, stretching exercise). The total training volume was equalized among training groups. MAIN OUTCOME MEASURES: Lean leg mass was assessed by a dual-energy x-ray absorptiometry; functional capacity was assessed by Short Physical Performance Battery and Timed Up and Go test; and QoL was assessed by Kidney Disease QoL Instrument, inflammatory markers, and sarcopenia. RESULTS: After the training period, the HLG increased lean leg mass compared with the CG. The HLG also displayed improvements in the pain and physical function domains. The skeletal muscle index and functional capacity increased in both RT protocols. The prevalence of sarcopenia was reduced 14.3% and 25% in the MLG and HLG, respectively, while there was an increase of 10% in the CG. No differences were observed in cytokines after intervention. CONCLUSIONS: High-load intradialytic RT was associated with gains in lean leg mass and QoL while functional capacity, appendicular muscle mass, and sarcopenia status were improved regardless of the RT load.

The effect of artichoke on lipid profile: A review of possible mechanisms of action.

Cardiovascular disease is a highly prevalent issue worldwide, and one of its main manifestations, dyslipidaemia, needs more attention. Cooked artichoke (Cynara scolymus) hearts or artichoke leaf extract (ALE) are believed to be helpful in the treatment of dyslipidaemia. In this narrative review, we provide a brief overview of the potential impact of artichoke consumption on lipid profile. We appraised the Cochrane, MEDLINE and Web of Science databases, and included articles published between 2000 and June 2018 on intervention in humans only. The main potential of ALE administration observed on lipid profile relates to decreased serum LDL, total cholesterol and triglyceride concentrations, although no strong evidence for increasing HDL appears to exist. Evidence suggests that decreases of 8-49 mg/dL for LDL concentration, 12-55 mg/dL for total cholesterol, and 11-51 mg/dL for triglycerides, can be attributed to 2 to 3 g/d of ALE, in which its components luteolin and chlorogenic acid may play a key role. On the other hand, the effects of cooked artichoke hearts can be attributed mainly to its soluble fibres, particularly inulin. Despite the convincing evidence on its health benefits, additional long-term clinical trials are pivotal to fully elucidate the potential effects of ALE administration on positive cardiovascular outcomes.

Creatine supplementation and glycemic control: a systematic review.

The focus of this review is the effects of creatine supplementation with or without exercise on glucose metabolism. A comprehensive examination of the past 16 years of study within the field provided a distillation of key data. Both in animal and human studies, creatine supplementation together with exercise training demonstrated greater beneficial effects on glucose metabolism; creatine supplementation itself demonstrated positive results in only a few of the studies. In the animal studies, the effects of creatine supplementation on glucose metabolism were even more distinct, and caution is needed in extrapolating these data to different species, especially to humans. Regarding human studies, considering the samples characteristics, the findings cannot be extrapolated to patients who have poorer glycemic control, are older, are on a different pharmacological treatment (e.g., exogenous insulin therapy) or are physically inactive. Thus, creatine supplementation is a possible nutritional therapy adjuvant with hypoglycemic effects, particularly when used in conjunction with exercise.

Gut microbiota, probiotics and diabetes.

Diabetes is a condition of multifactorial origin, involving several molecular mechanisms related to the intestinal microbiota for its development. In type 2 diabetes, receptor activation and recognition by microorganisms from the intestinal lumen may trigger inflammatory responses, inducing the phosphorylation of serine residues in insulin receptor substrate-1, reducing insulin sensitivity. In type 1 diabetes, the lowered expression of adhesion proteins within the intestinal epithelium favours a greater immune response that may result in destruction of pancreatic ß cells by CD8+ T-lymphocytes, and increased expression of interleukin-17, related to autoimmunity. Research in animal models and humans has hypothesized whether the administration of probiotics may improve the prognosis of diabetes through modulation of gut microbiota. We have shown in this review that a large body of evidence suggests probiotics reduce the inflammatory response and oxidative stress, as well as increase the expression of adhesion proteins within the intestinal epithelium, reducing intestinal permeability. Such effects increase insulin sensitivity and reduce autoimmune response. However, further investigations are required to clarify whether the administration of probiotics can be efficiently used for the prevention and management of diabetes.

Standardization of gut microbiome analysis in sports.

The gut microbiome plays a significant role in physiological functions such as nutrient processing, vitamin production, inflammatory response, and immune modulation, which, in turn, are important contributors to athlete health and performance. To date, the interpretation, discussion, and visualization of microbiome results of athletes are challenging, due to a lack of standard parameters and reference data for collection and comparison. The purpose of this perspective piece is to provide researchers with an easy-to-understand framework for the collection, analysis, and data management related to the gut microbiome with a specific focus on athletic populations. In the absence of a consensus on microbiome research in the sports field, we hope that these considerations serve as foundational "best practice." Adherence to these standard operating procedures will accelerate the path toward improving the quality of data and ultimately our understanding of the influence of the gut microbiome in sport settings.

Impact of oral nutritional supplement composition on healing of different chronic wounds: A systematic review.

Chronic wounds are characterized by prolonged non-healing, significantly affecting patients' quality of life. Oral formulas may enhance the wound healing process and contribute to cost reduction in care. This review aimed to evaluate the effects of oral nutritional supplementation on chronic wound healing and provide insights into formula characteristics. A comprehensive search across Cinahl, Embase, PubMed, and Web of Science databases yielded nine studies from the past decade involving 741 patients ages 52 to 81.7 across various care settings: hospitals, long-term care facilities, and home care. Primary wound types included pressure injuries (58%), diabetic foot ulcers (40%), and venous ulcers (2%). The intervention duration ranged from 2 to 16 wk, with sample sizes varying from 24 to 270 patients. Notably, four studies reported a reduction in wound area and an increased healing rate with a hypercaloric, hyperproteic formula enriched with zinc and vitamins A, C, and E. However, two studies found no significant differences compared with control groups. Two other studies investigated a combination of arginine, glutamine, and ß-hydroxy-ß-methylbutyrate; however, they did not yield significant results, and one study favored a hyperproteic formula instead of a hyperproteic formula with arginine. This review provides evidence supporting the potential of oral nutritional supplementation to enhance the healing process of chronic wounds. Based on our findings, a desirable formula should be characterized by a high calorie and protein content and the inclusion of antioxidant micronutrients, including, but not limited to, vitamins A, E, C, and zinc.

The impact of the obesity onset on the inflammatory and glycemic profile of women with severe obesity.

BACKGROUND: The stage of life at the onset of obesity is an important factor in assessing inflammatory state and cardiometabolic risk. OBJECTIVES: This study aimed to evaluate the relationship between the obesity onset and the inflammatory profile in women with severe obesity. SETTING: Public hospital, Brazil. METHODS: Forty-eight women with severe obesity (20-59 yr old) were evaluated according to weight, height, neck circumference (NC), waist circumference (WC), and hip circumference, as well blood metabolic and inflammatory parameters. The participants were grouped according to obesity onset stage of life (early group: ≤19 yr; late group: >19 yr). RESULTS: The demographic means of the participants were: age of 39.7 years, weight of 122.7 kg and body mass index (BMI) of 48.4 kg/m2. The late group presented significantly higher values of leptin (lep)/adiponectin (adipo) ratio and homeostatic model assessment for insulin resistance (HOMA-IR) than the early group. The late group also had a lower adipo/lep ratio. Moreover, the late group showed correlations between the lep/adipo ratio and BMI (r = .460, P = .021), NC (r = .478, P = .016), and WC (r = .535, P = .006). Adipo was also correlated with NC (r = -.418, P = .038), WC (r = -.437, P = .029), and glycated hemoglobin (HbA1C) (r = -.485, P = .019). By contrast, in the early group, the lep/adipo ratio showed correlations with insulin (r = .647, P = .004) and HOMA-B (r = .564, P = .015). CONCLUSIONS: The inflammatory profile is correlated with anthropometric values in women with late-onset obesity. Inflammatory markers seemed to correlate with the glycemic profile in women with early-onset obesity. Furthermore, inflammation was higher in women with late-onset obesity compared to those with early-onset obesity.

The Effects of Ketogenic Diet on Insulin Sensitivity and Weight Loss, Which Came First: The Chicken or the Egg?

The ketogenic diet (KD) is, nowadays, considered an interesting nutritional approach for weight loss and improvement in insulin resistance. Nevertheless, most of the studies available in the literature do not allow a clear distinction between its effects on insulin sensitivity per se, and the effects of weight loss induced by KDs on insulin sensitivity. In this review, we discuss the scientific evidence on the direct and weight loss mediated effects of KDs on glycemic status in humans, describing the KD's biochemical background and the underlying mechanisms.

Impact of Chemotherapy Regimens on Body Composition of Breast Cancer Women: A Multicenter Study across Four Brazilian Regions.

This study aimed to investigate the effect of chemotherapy (CT) and its different types of regimens on the anthropometry and body composition of women with breast cancer. Three-hundred-and-four women with breast cancer were enrolled in this multicenter study. The participants were evaluated before the infusion of the first cycle of CT (pre-CT), and until two weeks after CT completion (post-CT), regarding body weight, body mass index (BMI); waist circumference (WC); waist-to-height ratio (WHtR); conicity index (C-index); fat mass index (FMI); and fat-free mass index (FFMI). CT regimens were classified as anthracycline-based (AC-doxorubicin or epirubicin); anthracyclines and taxane (ACT); cyclophosphamide, methotrexate, and 5-fluorouracil (CMF); or isolated taxanes (paclitaxel or docetaxel). Women significantly increased BMI and FMI post-CT (p < 0.001 and p = 0.007, respectively). The ACT regimen increased FMI (p < 0.001), while FFMI increased after AC (p = 0.007). It is concluded that the CT negatively impacted body composition and the type of regime had a strong influence. The ACT regimen promoted an increase in FMI compared to other regimens, and the AC increased FFMI. These findings reinforce the importance of nutritional monitoring of breast cancer patients throughout the entire CT treatment.

A Protocol of Intradialytic Exercise for Improvements in Inflammatory Status, Body Composition, and Functional Capacity.

Skeletal muscle wasting has been well-documented among hemodialysis patients. This catabolic condition can be induced by numerous factors, including low-grade inflammation, and is associated with impairments in functional capacity and quality of life, as well as an increased mortality risk. We previously showed that 12 weeks of intradialytic resistance training increases lean mass, functional capacity, and the quality of life of hemodialysis patients. This chapter provides the details of a protocol of intradialytic exercise that leads to improvements in inflammatory status, body composition, and functional capacity.

Factors that Moderate the Effect of Nitrate Ingestion on Exercise Performance in Adults: A Systematic Review with Meta-Analyses and Meta-Regressions.

To identify how variables such as exercise condition, supplementation strategy, participant characteristics and demographics, and practices that control oral microbiota diversity could modify the effect of inorganic nitrate ingestion (as nitrate salt supplements, beetroot juice, and nitrate-rich vegetables) on exercise performance, we conducted a systematic review with meta-analysis. Studies were identified in PubMed, Embase, and Cochrane databases. Eligibility criteria included randomized controlled trials assessing the effect of inorganic nitrate on exercise performance in healthy adults. To assess the variation in effect size, we used meta-regression models for continuous variables and subgroup analysis for categorical variables. A total of 123 studies were included in this meta-analysis, comprising 1705 participants. Nitrate was effective for improving exercise performance (standardized mean difference [SMD]: 0.101; 95% CI: 0.051, 0.151, P <0.001, I2 = 0%), although nitrate salts supplementation was not as effective (P = 0.629) as ingestion via beetroot juice (P <0.001) or a high-nitrate diet (P = 0.005). Practices that control oral microbiota diversity influenced the nitrate effect, with practices harmful to oral bacteria decreasing the ergogenic effect of nitrate. The ingestion of nitrate was most effective for exercise lasting between 2 and 10 min (P <0.001). An inverse dose-response relation between the fraction of inspired oxygen and the effect size (coefficient: -0.045, 95% CI: -0.085, -0.005, P = 0.028) suggests that nitrate was more effective in increasingly hypoxic conditions. There was a dose-response relation for acute administration (P = 0.049). The most effective acute dose was between 5 and 14.9 mmol provided ≥150 min prior to exercise (P <0.001). An inverse dose-response for protocols ≥2 d was observed (P = 0.025), with the optimal dose between 5 and 9.9 mmol·d-1 (P <0.001). Nitrate, via beetroot juice or a high-nitrate diet, improved exercise performance, in particular, in sessions lasting between 2 and 10 min. Ingestion of 5-14.9 mmol⋅d-1 taken ≥150 min prior to exercise appears optimal for performance gains and athletes should be aware that practices controlling oral microbiota diversity may decrease the effect of nitrate.

Sex and population-specific cutoff values of muscle quality index: Results from NHANES 2011-2014.

BACKGROUND & AIMS: Muscle quality index (MQI) is used to measure the quality of the muscles. It is defined as the ratio of muscle strength per unit of muscle mass, but since this might vary by rage and ethnicity, we aimed to develop sex, and population-specific normative data and cutoff values for MQI (extremally low and low) using the arm or appendicular skeletal muscle mass (ASM) obtained from a population-representative sample. METHODS: This cross-sectional analysis included data from 4849 volunteers (aged 20-59 years) from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Measures of handgrip strength (HGS) were performed using a hand dynamometer. ASM was assessed by dual-energy X-ray absorptiometry (DXA). Arm ASM mass was used to calculate MQIArm [dominant HGS/dominant arm ASM (kg/kg)]; ASM was used to calculate MQIApp [dominant HGS/ASM (kg/kg)]; and the sum of the non-dominant hand and dominant hand were used to calculate MQItotal [HGS sum/ASM (kg/kg)]. Cutoff values were derived from a young reference subgroup (n = 1625 aged, 20-39 years), with low and extremely low MQI defined as 1 and 2 sex-specific standard deviations below the mean, respectively. RESULTS: MQIArm, MQIApp, and MQITotal differed by sex and population studied. Overall, using the proposed cutoffs, men showed lower values of MQIArm than women, and higher MQIApp, and MQITotal values. Compared to non-Hispanic Whites, non-Hispanic Asians had higher values of MQI while non-Hispanic Black people had lower values. CONCLUSION: MQIs cutoffs were established for both sexes and different populations studied. MQIArm, MQIApp, and MQITotal values were lower after the fifth-decade in men, but not in women.