Effect of Acute and Chronic Oral l-Carnitine Supplementation on Exercise Performance Based on the Exercise Intensity: A Systematic Review

l-Carnitine (l-C) and any of its forms (glycine-propionyl l-Carnitine (GPL-C) or l-Carnitine l-tartrate (l-CLT)) has been frequently recommended as a supplement to improve sports performance due to, among others, its role in fat metabolism and in maintaining the mitochondrial acetyl-CoA/CoA ratio. The main aim of the present systematic review was to determine the effects of oral l-C supplementation on moderate- (50–79% V˙O_{2 max}) and high-intensity (≥80% V˙O_{2 max}) exercise performance and to show the effective doses and ideal timing of its intake. A structured search was performed according to the PRISMA^® statement and the PICOS guidelines in the Web of Science (WOS) and Scopus databases, including selected data obtained up to 24 October 2021. The search included studies where l-C or glycine-propionyl l-Carnitine (GPL-C) supplementation was compared with a placebo in an identical situation and tested its effects on high and/or low–moderate performance. The trials that used the supplementation of l-C together with additional supplements were eliminated. There were no applied filters on physical fitness level, race, or age of the participants. The methodological quality of studies was evaluated by the McMaster Critical Review Form. Of the 220 articles obtained, 11 were finally included in this systematic review. Six studies used l-C, while three studies used l-CLT, and two others combined the molecule propionyl l-Carnitine (PL-C) with GPL-C. Five studies analyzed chronic supplementation (4–24 weeks) and six studies used an acute administration (<7 days). The administration doses in this chronic supplementation varied from 1 to 3 g/day; in acute supplementation, oral l-C supplementation doses ranged from 3 to 4 g. On the one hand, the effects of oral l-C supplementation on high-intensity exercise performance variables were analyzed in nine studies. Four of them measured the effects of chronic supplementation (lower rating of perceived exertion (RPE) after 30 min at 80% V˙O_{2 max} on cycle ergometer and higher work capacity in “all-out” tests, peak power in a Wingate test, and the number of repetitions and volume lifted in leg press exercises), and five studies analyzed the effects of acute supplementation (lower RPE after graded exercise test on the treadmill until exhaustion and higher peak and average power in the Wingate cycle ergometer test). On the other hand, the effects of l-C supplementation on moderate exercise performance variables were observed in six studies. Out of those, three measured the effect of an acute supplementation, and three described the effect of a chronic supplementation, but no significant improvements on performance were found. In summary, l-C supplementation with 3 to 4 g ingested between 60 and 90 min before testing or 2 to 2.72 g/day for 9 to 24 weeks improved high-intensity exercise performance. However, chronic or acute l-C or GPL-C supplementation did not present improvements on moderate exercise performance.     

Short-Term Very High Carbohydrate Diet and Gut-Training Have Minor Effects on Gastrointestinal Status and Performance in Highly Trained Endurance Athletes

We implemented a multi-pronged strategy (MAX) involving chronic (2 weeks high carbohydrate [CHO] diet + gut-training) and acute (CHO loading + 90 g·h⁻¹ CHO during exercise) strategies to promote endogenous and exogenous CHO availability, compared with strategies reflecting lower ranges of current guidelines (CON) in two groups of athletes. Nineteen elite male race walkers (MAX: 9; CON:10) undertook a 26 km race-walking session before and after the respective interventions to investigate gastrointestinal function (absorption capacity), integrity (epithelial injury), and symptoms (GIS). We observed considerable individual variability in responses, resulting in a statistically significant (p < 0.001) yet likely clinically insignificant increase (Δ 736 pg·mL⁻¹) in I-FABP after exercise across all trials, with no significant differences in breath H₂ across exercise (p = 0.970). MAX was associated with increased GIS in the second half of the exercise, especially in upper GIS (p < 0.01). Eighteen highly trained male and female distance runners (MAX: 10; CON: 8) then completed a 35 km run (28 km steady-state + 7 km time-trial) supported by either a slightly modified MAX or CON strategy. Inter-individual variability was observed, without major differences in epithelial cell intestinal fatty acid binding protein (I-FABP) or GIS, due to exercise, trial, or group, despite the 3-fold increase in exercise CHO intake in MAX post-intervention. The tight-junction (claudin-3) response decreased in both groups from pre- to post-intervention. Groups achieved a similar performance improvement from pre- to post-intervention (CON = 39 s [95 CI 15–63 s]; MAX = 36 s [13–59 s]; p = 0.002). Although this suggests that further increases in CHO availability above current guidelines do not confer additional advantages, limitations in our study execution (e.g., confounding loss of BM in several individuals despite a live-in training camp environment and significant increases in aerobic capacity due to intensified training) may have masked small differences. Therefore, athletes should meet the minimum CHO guidelines for training and competition goals, noting that, with practice, increased CHO intake can be tolerated, and may contribute to performance outcomes.     

Randomized Controlled Trial of Exercise and Nutrition Supplementation on Physical and Cognitive Function in Older Chinese Adults Aged 50 Years and Older

ObjectivesTo assess whether a 24-week multidomain lifestyle intervention including a nutritional milk supplement and an exercise program had any effect on physical and cognitive function, self-rated health, and health-related quality of life in older Chinese adults.DesignRandomized controlled trial.Setting and participantsCommunity-living people aged 50 years and older.Methods180 participants (mean age 61 ± 6 years) were randomized to 24 weeks of exercise plus nutrition supplementation or no intervention. The primary outcome was gait speed, with additional physical and cognitive function measures, self-rated health, and health-related quality of life as secondary outcomes. Information collected also included dietary intake by 3-day dietary records, and blood sampling for renal function, glycated hemoglobin, serum vitamin B₁₂, 25-hydroxyvitamin D, and biochemical indices of bone turnover.ResultsThere was no significant group difference in the change of gait speed, muscle strength, muscle power, cardiovascular fitness, or cognitive function over time, either by intention-to-treat or per-protocol analysis. A significant time × group effect (P = .039) on self-rated health was detected, but there was no significant time or time × group difference in the change of physical and mental health-related quality of life measures over time. In addition, moderate physical activity level was greatly increased from baseline to 24 weeks in the intervention group compared with the control group.Conclusions and implicationsA 24-week exercise and nutrition supplementation program among community-living people in late midlife to early old age improved self-rated health and the overall level of physical activity, without objective improvements in physical and cognitive function.     

Acute Paraxanthine Ingestion Improves Cognition and Short-Term Memory and Helps Sustain Attention in a Double-Blind,Placebo-Controlled,Crossover Trial

This study examined the effects of acute paraxanthine (PXN) ingestion on markers of cognition, executive function, and psychomotor vigilance. In a randomized, double blind, placebo-controlled, crossover, and counterbalanced manner, 13 healthy male and female participants were randomly assigned to consume a placebo (PLA) or 200 mg of PXN (ENFINITY™, Ingenious Ingredients, L.P.). Participants completed stimulant sensitivity and side effect questionnaires and then performed the Berg Wisconsin Card Sorting Test (BCST), the Go/No-Go test (GNG), the Sternberg task test (STT), and the psychomotor vigilance task test (PVTT). Participants then ingested one capsule of PLA or PXN treatment. Participants completed side effect and cognitive function tests after 1, 2, 3, 4, 5, and 6 h after ingestion of the supplement. After 7 days, participants repeated the experiment while consuming the alternative treatment. Data were analyzed by general linear model (GLM) univariate analyses with repeated measures using body mass as a covariate, and by assessing mean and percent changes from baseline with 95% confidence intervals (CIs) expressed as means (LL, UL). PXN decreased BCST errors (PXN −4.7 [−0.2, −9.20], p = 0.04; PXN −17.5% [−36.1, 1.0], p = 0.06) and perseverative errors (PXN −2.2 [−4.2, −0.2], p = 0.03; PXN −32.8% [−64.4, 1.2], p = 0.04) at hour 6. GNG analysis revealed some evidence that PXN ingestion better maintained mean accuracy over time and Condition R Round 2 response time (e.g., PXN −25.1 [−52.2, 1.9] ms, p = 0.07 faster than PLA at 1 h), suggesting better sustained attention. PXN ingestion improved STT two-letter length absent and present reaction times over time as well as improving six-letter length absent reaction time after 2 h (PXN −86.5 ms [−165, −7.2], p = 0.03; PXN −9.0% [−18.1, 0.2], p = 0.05), suggesting that PXN enhanced the ability to store and retrieve random information of increasing complexity from short-term memory. A moderate treatment x time effect size (η_p² = 0.08) was observed in PVTT, where PXN sustained vigilance during Trial 2 after 2 h (PXN 840 ms [103, 1576], p = 0.03) and 4 h (PXN 1466 ms [579, 2353], p = 0.002) compared to PL. As testing progressed, the response time improved during the 20 trials and over the course of the 6 h experiment in the PXN treatment, whereas it significantly increased in the PL group. The results suggest that acute PXN ingestion (200 mg) may affect some measures of short-term memory, reasoning, and response time to cognitive challenges and help sustain attention.     

Coffee Increases Post-Exercise Muscle Glycogen Recovery in Endurance Athletes: A Randomized Clinical Trial

Coffee is one of the most widely consumed beverages worldwide and caffeine is known to improve performance in physical exercise. Some substances in coffee have a positive effect on glucose metabolism and are promising for post-exercise muscle glycogen recovery. We investigated the effect of a coffee beverage after exhaustive exercise on muscle glycogen resynthesis, glycogen synthase activity and glycemic and insulinemic response in a double-blind, crossover, randomized clinical trial. Fourteen endurance-trained men performed an exhaustive cycle ergometer exercise to deplete muscle glycogen. The following morning, participants completed a second cycling protocol followed by a 4-h recovery, during which they received either test beverage (coffee + milk) or control (milk) and a breakfast meal, with a simple randomization. Blood samples and muscle biopsies were collected at the beginning and by the end of recovery. Eleven participants were included in data analysis (age: 39.0 ± 6.0 years; BMI: 24.0 ± 2.3 kg/m²; VO_2max: 59.9 ± 8.3 mL·kg⁻¹·min⁻¹; PPO: 346 ± 39 W). The consumption of coffee + milk resulted in greater muscle glycogen recovery (102.56 ± 18.75 vs. 40.54 ± 18.74 mmol·kg dw⁻¹; p = 0.01; d = 0.94) and greater glucose (p = 0.02; d = 0.83) and insulin (p = 0.03; d = 0.76) total area under the curve compared with control. The addition of coffee to a beverage with adequate amounts of carbohydrates increased muscle glycogen resynthesis and the glycemic and insulinemic response during the 4-h recovery after exhaustive cycling exercise.     

Glucose and Fructose Supplementation and Their Acute Effects on Anaerobic Endurance and Resistance Exercise Performance in Healthy Individuals: A Double-Blind Randomized Placebo-Controlled Crossover Trial

Background: The effects of glucose, fructose and a combination of these on physical performance have been subject of investigation, resulting in diverse findings. Objective: The aim of this study was to investigate how an individualized amount of glucose, fructose, and a combination of these compared to placebo (sucralose) alter endurance performance on a cycle ergometer, lower and upper body resistance exercise performance at individualized thresholds in healthy young individuals. Methods: A total of 16 healthy adults (9 females) with an age of 23.8 ± 1.6 years and a BMI of 22.6 ± 1.8 kg/m² (body mass (BM) 70.9 ± 10.8 kg, height 1.76 ± 0.08 m) participated in this study. During the screening visit, the lactate turn point 2 (LTP2) was defined and the weights for chest-press and leg-press were determined. Furthermore, 30 min prior to each exercise session, participants received either 1 g/kg BM of glucose (Glu), 1 g/kg BM of fructose (Fru), 0.5 g/kg BM of glucose/fructose (GluFru) (each), or 0.2 g sucralose (placebo), respectively, which were dissolved in 300 mL of water. All exercises were performed until volitional exhaustion. Time until exhaustion (TTE) and cardio-pulmonary variables were determined for all cycling visits; during resistance exercise, repetitions until muscular failure were counted and time was measured. During all visits, capillary blood glucose and blood lactate concentrations as well as venous insulin levels were measured. Results: TTE in cycling was 449 ± 163 s (s) (Glu), 443 ± 156 s (Fru), 429 ± 160 s (GluFru) and 466 ± 162 s (Pla) (p = 0.48). TTE during chest-press sessions was 180 ± 95 s (Glu), 180 ± 92 s (Fru), 172 ± 78 s (GluFru) and 162 ± 66 s (Pla) (p = 0.25), respectively. Conclusions: Pre-exercise supplementation of Glu, Fru and a combination of these did not have an ergogenic effect on high-intensity anaerobic endurance performance and on upper and lower body moderate resistance exercise in comparison to placebo.     

An Organic Khorasan Wheat-Based Replacement Diet Improves Risk Profile of Patients with Acute Coronary Syndrome: A Randomized Crossover Trial

Khorasan wheat is an ancient grain with previously reported health benefits in clinically healthy subjects. The aim of this study was to examine whether a replacement diet, thereby substituting all other cereal grains, with products made with organic khorasan wheat could provide additive protective effects in reducing lipid, oxidative and inflammatory risk factors, in patients with Acute Coronary Syndromes (ACS) in comparison to a similar replacement diet using products made from organic modern wheat. A randomized double-blinded crossover trial with two intervention phases was conducted on 22 ACS patients (9 F; 13 M). The patients were assigned to consume products (bread, pasta, biscuits and crackers) made either from organic semi-whole khorasan wheat or organic semi-whole control wheat for eight weeks in a random order. On average, patients ingested 62.0 g dry weight (DW) day⁻¹ khorasan or control semolina; and 140.5 g DW day⁻¹ khorasan or control flour, respectively. An eight-week washout period was implemented between the respective interventions. Blood analyses were performed both at the beginning and end of each intervention phase; thereby permitting a comparison of both the khorasan and control intervention phases, respectively, on circulatory risk factors for the same patient. Consumption of products made with khorasan wheat resulted in a significant amelioration in total cholesterol (−6.8%), low-density lipoprotein cholesterol (LDL-C) (−8.1%) glucose (−8%) and insulin (−24.6%) from baseline levels, independently of age, sex, traditional risk factors, medication and diet quality. Moreover, there was a significant reduction in reactive oxygen species (ROS), lipoperoxidation of circulating monocytes and lymphocytes, as well as in the levels of Tumor Necrosis Factor-alpha. No significant differences from baseline in the same patients were observed after the conventional control wheat intervention phase. The present results suggest that a replacement diet with cereal products made from organic khorasan wheat provides additional protection in patients with ACS. Circulating cardiovascular risk factors, including lipid parameters, and markers of both oxidative stress and inflammatory status, were reduced, irrespective of the number and combination of medicinal therapies with proven efficacy in secondary prevention.     

The Influence of Nutrition and Physical Activity on Exercise Performance after Mild COVID-19 Infection in Endurance Athletes-CESAR Study

COVID-19 and imposed restrictions are linked with numerous health consequences, especially among endurance athletes (EA). Unfavorable changes in physical activity and nutrition may affect later sports and competition performance. The aims of this study were: (1) to assess the impact of COVID-19 infection and pandemic restrictions on the nutrition and physical activity of EAs and (2) to compare them with the results of cardiopulmonary exercise testing (CPET). In total, 49 EAs (n_male = 43, n_female = 6, mean age = 39.9 ± 7.8 year., height = 178.4 ± 6.8 cm, weight = 76.3 ± 10.4 kg; BMI = 24.0 ± 2.6 kg·m⁻²) underwent pre- and post-COVID-19 CPET and fulfilled the dietary and physical activity survey. COVID-19 infection significantly deteriorated CPET performance. There was a reduction in oxygen uptake and in heart rate post-COVID-19 (both p < 0.001). Consuming processed meat and replacing meat with plant-based protein affected blood lactate concentration (p = 0.035). Fat-free mass was linked with consuming unsaturated fatty acids (p = 0.031). Adding salt to meals influenced maximal speed/power (p = 0.024) and breathing frequency (p = 0.033). Dietary and Fitness Practitioners and Medical Professionals should be aware of possible COVID-19 infection and pandemic consequences among EA. The results of this study are a helpful guideline to properly adjust the treatment, nutrition, and training of EA.     

Nutrition-Education Program Improves Preschoolers' At-Home Diet: A Group Randomized Trial

ObjectiveThis study evaluated whether a nutrition-education program in child-care centers improved children's at-home daily consumption of fruits and vegetables, at-home use of low-fat/fat-free milk, and other at-home dietary behaviors.Materials and methodsTwenty-four child-care centers serving low-income families were matched by region, type, and size, and then randomly assigned to either an intervention or control condition. In the 12 intervention centers, registered dietitian nutritionists provided nutrition education to children and parents separately during a 6- to 10-week period. They also held two training sessions for center staff, to educate them on healthy eating and physical activity policies at the centers, and distributed weekly parent newsletters that included activities and recipes. Parents (n=1,143) completed a mail or telephone survey at baseline and follow-up to report information on their child's fruit, vegetable, and milk consumption and other dietary behaviors at home. This study used general and generalized linear mixed models to evaluate program impacts, while accounting for the clustering of children within centers. This study included child age, child sex, household size, respondent race/ethnicity, respondent age, and respondent sex as covariates.ResultsThe program had a substantial impact on children's at-home daily consumption of vegetables and use of low-fat/fat-free milk. This study also found a significant increase in the frequency of child-initiated vegetable snacking, which might have contributed to the significant increase in vegetable consumption. The program did not have a significant impact on fruit consumption or parental offerings of fruits and vegetables, child-initiated fruit snacking, or child fruit consumption.ConclusionsThis intervention in child-care settings that emphasized children, parents, and teachers significantly increased at-home vegetable and low-fat/fat-free milk consumption among low-income preschoolers.     

Short-Term Pilot Study to Evaluate the Impact of Salbi Educa Nutrition App in Macronutrients Intake and Adherence to the Mediterranean Diet: Randomized Controlled Trial

Promoting a healthy diet is a relevant strategy for preventing non-communicable diseases. This study aims to evaluate the impact of an innovative tool, the SAlBi educa nutrition app, in primary healthcare dietary counseling to improve dietary profiles as well as adherence to the Mediterranean diet. A multi-center randomized control trial comprising 104 participants was performed. Both control (n = 49) and intervention (n = 55) groups attended four once-weekly sessions focusing on healthy eating habits and physical activity, over one month. As well as attending the meetings, the intervention group used the app, which provides self-monitoring and tailored dietary advice based on the Mediterranean diet model. In a second intervention (one arm trial), the potential of SAlBi educa was evaluated for three months during the COVID-19 pandemic. At 4 weeks, the intervention group had significantly increased their carbohydrate intake (7.7% (95% CI: 0.16 to 15.2)) and decreased their total fat intake (−5.7% (95% CI: −10.4 to −1.15)) compared to the control group. Significant differences were also found for carbohydrates (3.5% (95% CI: −1.0 to 5.8)), total fats (−5.9% (95% CI: −8.9 to −3.0)), fruits and vegetables (266.3 g/day (95% CI: 130.0 to 402.6)), legumes (7.7g/day (95% CI: 0.2 to 15.1)), starchy foods (36.4 g/day (95% CI: 1.1 to 71.7)), red meat (−17.5 g/day (95% CI: −34.0 to −1.1)), and processed meat (−6.6 g/day (95% CI: −13.1 to −0.1)) intakes during the COVID-19 pandemic. SAlBi educa is a useful tool to support nutrition counseling in primary healthcare, including in special situations such as the COVID-19 pandemic. Trial registration: ISRCTN57186362.     

Green Juice in Human Metabolism: A Randomized Trial

ABSTRACT

Objective: Fruits and vegetables contain many compounds presenting potential antioxidant activity. The objective of this study was to evaluate the effect of a green juice recipe in adult metabolism in order to identify new preventive dietary sources.

Method: This was a single-blind randomized controlled clinical trial. Recruitment and data were, respectively, made and collected at the Universidade Federal de Ciências da Saúde de Porto Alegre. Individuals who met all the inclusion criteria during the period of recruitment were included. Green juice (experimental group) or placebo (control group) were consumed from Monday to Friday between 8 and 9 am, in the amount of 300 mL for 60 days (except Saturdays and Sundays). To verify the effect of green juice on metabolism, the following were evaluated: (a) glycemia, plasma lipid profile, renal and liver functions, redox profile, and antioxidant enzymes; (b) anthropometry; and (c) well-being and anxiety.

Results: This study included 14 participants in the test group (juice group) and 13 controls (placebo group), with mean ages of 31.07 and 30.15 years, respectively. We did not observe a significant difference between the treatments. Dietary properties of vegetable and fruit juices are an area of significant interest.

Conclusions: Together with an analysis of previous works, we suggest that green juice did not cause an improvement in metabolic function and there is a need for further research on this issue, mainly through different interventions and other samples.     

Fucoidan Supplementation Improves Exercise Performance and Exhibits Anti-Fatigue Action in Mice

Fucoidan (FCD) is a well-known bioactive constituent of seaweed extract that possess a wide spectrum of activities in biological systems, including anti-cancer, anti-inflammation and modulation of immune systems. However, evidence on the effects of FCD on exercise performance and physical fatigue is limited. Therefore, we investigated the potential beneficial effects of FCD on ergogenic and anti-fatigue functions following physiological challenge. Male ICR mice from three groups (n = 8 per group) were orally administered FCD for 21 days at 0, 310 and 620 mg/kg/day, which were, respectively, designated the vehicle, FCD-1X and FCD-2X groups. The results indicated that the FCD supplementations increased the grip strength (p = 0.0002) and endurance swimming time (p = 0.0195) in a dose-depend manner. FCD treatments also produced dose-dependent decreases in serum levels of lactate (p < 0.0001) and ammonia (p = 0.0025), and also an increase in glucose level (p < 0.0001) after the 15-min swimming test. In addition, FCD supplementation had few subchronic toxic effects. Therefore, we suggest that long-term supplementation with FCD can have a wide spectrum of bioactivities on health promotion, performance improvement and anti-fatigue.     

Effects of Diets Supplemented with Branched-Chain Amino Acids on the Performance and Fatigue Mechanisms of Rats Submitted to Prolonged Physical Exercise

This study aimed to determine the effects of diets chronically supplemented with branched-chain amino acids (BCAA) on the fatigue mechanisms of trained rats. Thirty-six adult Wistar rats were trained for six weeks. The training protocol consisted of bouts of swimming exercise (one hour a day, five times a week, for six weeks). The animals received a control diet (C) (n = 12), a diet supplemented with 3.57% BCAA (S1) (n = 12), or a diet supplemented with 4.76% BCAA (S2) (n = 12). On the last day of the training protocol, half the animals in each group were sacrificed after one hour of swimming (1H), and the other half after a swimming exhaustion test (EX). Swimming time until exhaustion was increased by 37% in group S1 and reduced by 43% in group S2 compared to group C. Results indicate that the S1 diet had a beneficial effect on performance by sparing glycogen in the soleus muscle (p < 0.05) and by inducing a lower concentration of plasma ammonia, whereas the S2 diet had a negative effect on performance due to hyperammonemia (p < 0.05). The hypothalamic concentration of serotonin was not significantly different between the 1H and EX conditions. In conclusion, chronic BCAA supplementation led to increased performance in rats subjected to a swimming test to exhaustion. However, this is a dose-dependent effect, since chronic ingestion of elevated quantities of BCAA led to a reduction in performance.     

Effects of Nitrate Supplementation on Exercise Performance in Humans: A Narrative Review

Nitrates have become increasingly popular for their potential role as an ergogenic aid. The purpose of this article was to review the current scientific evidence of nitrate supplementation on human performance. The current recommendation of nitrate supplementation is discussed, as well as possible health complications associated with nitrate intake for athletes, and dietary strategies of covering nitrate needs through sufficient intake of nitrate-rich foods alone are presented. Pubmed, Scopus, and Web of Science were searched for articles on the effects of nitrate supplementation in humans. Nitrates are an effective ergogenic aid when taken acutely or chronically in the range of ~5–16.8 mmol (~300–1041 mg) 2–3 h before exercise and primarily in the case of exercise duration of ~10–17 min in less trained individuals (VO_2max < 65 mL/kg/min). Nitrate needs are most likely meet by ingesting approximately 250–500 g of leafy and root vegetables per day; however, dietary supplements might represent a more convenient and accurate way of covering an athlete’s nitrate needs. Athletes should refrain from mouthwash usage when nitrate supplementation benefits are desired. Future research should focus on the potential beneficial effects of nitrate supplementation on brain function, possible negative impacts of chronic nitrate supplementation through different nitrate sources, and the effectiveness of nitrate supplementation on strength and high-intensity intermittent exercise.     

Acute Beetroot Juice Supplementation Enhances Intermittent Running Performance but Does Not Reduce Oxygen Cost of Exercise among Recreational Adults

Nitrate (NO₃⁻) supplementation has been reported to enhance intermittent exercise performance; however, its impact on oxygen (O₂) cost during intermittent running exercise is unclear. The aim of this study was to assess if acute NO₃⁻ supplementation would elicit performance benefits in recreationally active individuals during the Yo–Yo intermittent recovery level 1 (Yo-Yo IR1) test, with its potential benefit on O₂ consumption (VO₂), in a double-blind, randomized, crossover study, 12 recreational males consumed NO₃⁻-rich (NIT; ~12.8 mmol), and NO₃⁻-depleted (PLA; 0.04 mmol) concentrated beetroot juice 3 h before completing the Yo-Yo IR1 test. VO₂ was measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). Performance in the Yo–Yo IR1 was greater with NIT (990 ± 442.25 m) compared to PLA (870 ± 357.4 m, p = 0.007). The VO₂ was not significantly different at 160 m (1.92 ± 0.99 vs. 2.1 ± 0.88 L·min⁻¹), 280 m (2.62 ± 0.94 vs. 2.83 ± 0.94 L·min⁻¹), 440 m (3.26 ± 1.04 vs. 3.46 ± 0.98 L·min⁻¹) and peak (4.71 ± 1.01 vs. 4.92 ± 1.17 L·min⁻¹) between NIT and PLA trials (all p > 0.05). The present study has indicated that acute supplementation of NO₃⁻ enhanced intermittent running performance but had no effect on VO₂ during the Yo–Yo IR1 test in recreational young adults.     

Diet of an Olympian: Food with a purpose

Olympic medals are often decided by a fraction of a per cent. Over the last 20 years, elite athletes have taken a systematic approach to improving their performance. Performance nutrition is the systematic use of nutrition science to improve sporting performance and is increasingly being used by elite athletes. There are three areas of sporting performance where performance nutrition may be applied, namely the prevention of illness and injury, facilitation of adaptation from training and improvement of competition performance. Performance nutrition can help prevent illness by providing the correct amount of energy and macronutrients to match the energy needs of training and to prevent fatigue. Post‐exercise carbohydrate and protein intake supports recovery from exercise and enables athletes to be in a position to train again. Nutrients such as calcium can promote bone health and prevent injury. Nutrient intake around training facilitates the adaptation to exercise. Protein intake post resistance exercise enhances the hypertrophy adaptation to exercise and manipulation of carbohydrate intake facilitates the adaptive response to endurance exercise. Use of both macronutrients and ergogenic aids (such as beetroot juice) around competition can enhance the sporting performance.     

Effects of a Short-Term “Fat Adaptation with Carbohydrate Restoration” Diet on Metabolic Responses and Exercise Performance in Well-Trained Runners

Periodized carbohydrate availability can enhance exercise capacity, but the effects of short-term fat adaptation carbohydrate restoration (FACR) diets on metabolic responses and exercise performance in endurance athletes have not been conclusively determined. This study aimed to investigate the effect of a FACR diet on measures of resting metabolism, exercise metabolism, and exercise performance. Well-trained male runners (n = 8) completed a FACR dietary intervention (five days’ carbohydrate < 20% and fat > 60% energy, plus one-day carbohydrate ≥ 70% energy), and a control high-carbohydrate (HCHO) diet for six days (carbohydrate > 60% energy; fat < 20% energy) in a randomized crossover design. Pre- and post-intervention metabolic measures included resting metabolic rate (RMR), respiratory quotient (RQ), maximum fat oxidation rate during exercise (MFO), and maximum fat oxidation intensity (FATmax). Measures of exercise performance included maximal oxygen uptake (VO₂max), running economy (RE), and 5 km running time trial (5 km-TT). In FACR compared with HCHO, there were significant improvements in FATmax (p = 0.006) and RE (p = 0.048). There were no significant differences (p > 0.05) between FACR and HCHO in RMR, RQ, VO₂max, or 5 km-TT. Findings suggest that a short-term (six days) FACR diet may facilitate increased fat oxidation and submaximal exercise economy but does not improve 5 km-TT performance.     

Effect of a Four-Week Vegan Diet on Performance,Training Efficiency and Blood Biochemical Indices in CrossFit-Trained Participants

This interventional study examined the effect of a four-week vegan diet (Veg_D) during a four-week high-intensity functional training (HIFT) on performance, training results and blood biochemical indices in female (n = 12) and male (n = 8) moderate-trained CrossFit participants. The whole study group performed the maximum number of repetitions with a load of 70% one repetition-maximum (1RM) and a modified Fight Gone Bad (FGB_Mod) test before and after a dietary intervention (the group was divided to follow a Veg_D or a traditional mixed diet (Mix_D)) in a randomised and parallel design. Pre-exercise resting blood samples were also analysed. There was a significant improvement in the number of repetitions performed at a load corresponding to 70% of 1RM in the classic squat in the Mix_D group (p < 0.001), and in the classic deadlift in the Veg_D group (p = 0.014). Furthermore, there was a significant improvement in the results of the FGB_Mod performance test after a Mix_D. Moreover, an improvement in some exercises in the modified FGB_Mod test (Wall Ball after the Veg_D and the Mix_D, and rowing after the Mix_D) was also observed. However, differences between the Mix_D and the Veg_D groups were not clinically relevant. In conclusion, the short-term study conducted here indicated that a Veg_D in HIFT training positively affects strength endurance in the classic deadlift but is unlikely to be more beneficial in improving performance than a Mix_D.     

L-Carnitine Tartrate Supplementation for 5 Weeks Improves Exercise Recovery in Men and Women: A Randomized,Double-Blind,Placebo-Controlled Trial

L-carnitine tartrate has been shown to improve relatively short-term recovery among athletes. However, there is a lack of research on the longer-term effects in the general population. Objective: The primary objectives of this randomized double-blind, placebo-controlled trial were to evaluate the effects of daily L-carnitine tartrate supplementation for 5 weeks on recovery and fatigue. Method: In this study, eighty participants, 21- to 65-years-old, were recruited. Participants were split into two groups of forty participants each, a placebo, and a L-carnitine Tartrate group. Seventy-three participants completed a maintenance exercise training program that culminated in a high-volume exercise challenge. Results: Compared to placebo, L-carnitine tartrate supplementation was able to improve perceived recovery and soreness (p = 0.021), and lower serum creatine kinase (p = 0.016). In addition, L-carnitine tartrate supplementation was able to blunt declines in strength and power compared to placebo following an exercise challenge. Two sub-analyses indicated that these results were independent of gender and age. Interestingly, serum superoxide dismutase levels increased significantly among those supplementing with L-carnitine tartrate. Conclusions: These findings agree with previous observations among healthy adult subjects and demonstrate that L-carnitine tartrate supplementation beyond 35 days is beneficial for improving recovery and reducing fatigue following exercise across gender and age.     

Scientific Evidence of Interventions Using the Mediterranean Diet: A Systematic Review

The Mediterranean Diet has been associated with greater longevity and quality of life in epidemiological studies, the majority being observational. The application of evidence-based medicine to the area of public health nutrition involves the necessity of developing clinical trials and systematic reviews to develop sound recommendations. The purpose of this study was to analyze and review the experimental studies on Mediterranean diet and disease prevention. A systematic review was made and a total of 43 articles corresponding to 35 different experimental studies were selected. Results were analyzed for the effects of the Mediterranean diet on lipoproteins, endothelial resistance, diabetes and antioxidative capacity, cardiovascular diseases, arthritis, cancer, body composition, and psychological function. The Mediterranean diet showed favorable effects on lipoprotein levels, endothelium vasodilatation, insulin resistance, metabolic syndrome, antioxidant capacity, myocardial and cardiovascular mortality, and cancer incidence in obese patients and in those with previous myocardial infarction. Results disclose the mechanisms of the Mediterranean diet in disease prevention, particularly in cardiovascular disease secondary prevention, but also emphasize the need to undertake experimental research and systematic reviews in the areas of primary prevention of cardiovascular disease, hypertension, diabetes, obesity, infectious diseases, age-related cognitive impairment, and cancer, among others. Interventions should use food scores or patterns to ascertain adherence to the Mediterranean diet. Further experimental research is needed to corroborate the benefits of the Mediterranean diet and the underlying mechanisms, and in this sense the methodology of the ongoing PREDIMED study is explained.