Journal of the International Society of Sports Nutrition最新文献

Background: Fatigue and gastrointestinal (GI) distress are common among athletes with an estimated 30-90% of athletes participating in marathons, triathlons, or similar events experiencing GI complaints. Intense exercise can lead to increased intestinal permeability, potentially allowing members of the gut microbiota to permeate into the bloodstream, resulting in an inflammatory response and cascade of performance-limiting outcomes. Probiotics, through their capacity to regulate the composition of the gut microbiota, may act as an adjunctive therapy by enhancing GI and immune function while mitigating inflammatory responses. This review investigates the effectiveness of probiotic supplementation on fatigue, inflammatory markers, and exercise performance based on randomized controlled trials (RCTs).

Methods: This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and PICOS (Population, Intervention, Comparison, Outcome, Study design) framework. A comprehensive search was conducted in Sportdiscus, PubMed, and Scopus databases, and the screening of titles, abstracts, and full articles was performed based on pre-defined eligibility criteria. Of the 3505 records identified, 1884 were screened using titles and abstracts, of which 450 studies were selected for full-text screening. After final screening, 13 studies met the eligibility criteria and were included for review. The studies contained 513 participants, consisting of 351 males and 115 females, however, two studies failed to mention the sex of the participants. Among the participants, 246 were defined as athletes, while the remaining participants were classified as recreationally active (n = 267). All trials were fully described and employed a double- or triple-blind placebo-controlled intervention using either a single probiotic strain or a multi-strain synbiotic (containing both pro- and pre-biotics).

Results: This review assesses the effects of daily probiotic supplementation, ranging from 13 to 90 days, on physical performance and physiological markers in various exercise protocols. Ten studies reported improvements in various parameters, such as, enhanced endurance performance, improved anxiety and stress levels, decreased GI symptoms, and reduced upper respiratory tract infections (URTI). Moreover, despite no improvements in maximal oxygen uptake (VO₂), several studies demonstrated that probiotic supplementation led to amelioration in lactate, creatine kinase (CK), and ammonia concentrations, suggesting beneficial effects on mitigating exercise-induced muscular stress and damage.

Conclusion: Probiotic supplementation, specifically at a minimum dosage of 15 billion CFUs daily for a duration of at least 28 days, may contribute to the reduction of perceived or actual fatigue.

Background: Caffeine (CAF) ingestion improves performance in a broad range of exercise tasks. Nevertheless, the CAF-induced, dose-dependent effect on discipline-specific performance and cognitive functions in CrossFit/High-Intensity Functional Training (HIFT) has not been sufficiently investigated. The aim of this study was to evaluate the effect of acute supplementation of three different doses of CAF and placebo (PLA) on specific performance, reaction time (R_Time), postural stability (P_Stab), heart rate (HR) and perceived exertion (RPE).

Methods: In a randomized double-blind placebo-controlled crossover design, acute pre-exercise supplementation with CAF (3, 6, or 9 mg/kg body mass (BM)) and PLA in 26 moderately trained CrossFit practitioners was examined. The study protocol involved five separate testing sessions using the Fight Gone Bad test (FGB) as the exercise performance evaluation and biochemical analyses, HR and RPE monitoring, as well as the assessment of R_Time and P_Stab, with regard to CYP1A2 (rs762551) and ADORA2A (rs5751876) single nucleotide polymorphism (SNP).

Results: Supplementation of 6 mg_CAF/kg_BM induced clinically noticeable improvements in FGB_Total results, R_Time and pre-exercise motor time. Nevertheless, there were no significant differences between any CAF doses and PLA in FGB_Total, HR_max, HR_mean, RPE, pre/post-exercise R_Time, P_Stab variables or pyruvate concentrations. Lactate concentration was higher (p < 0.05) before and after exercise in all CAF doses than in PLA. There was no effect of CYP1A2 or ADORA2A SNPs on performance.

Conclusions: The dose-dependent effect of CAF supplementation appears to be limited to statistically nonsignificant but clinically considered changes on specific performance, R_Time, P_Stab, RPE or HR. However, regarding practical CAF-induced performance implications in CrossFit/HIFT, 6 mg_CAF/kg_BM may be supposed as the most rational supplementation strategy.

Background: Sports practice, particularly eccentric exercises, induces significant muscular changes, including muscle fiber injuries, strength loss, pain, and increased permeability of the muscle membrane. The duration of muscle recovery depends on factors such as exercise intensity and the specific muscle groups engaged. The inflammatory response plays a crucial role in muscle regeneration, involving various cell types. Curcumin, especially when its stability is enhanced through encapsulation, exhibits potent antioxidant and anti-inflammatory properties. Supplementing with curcumin can reduce muscle damage and inflammation caused by eccentric exercise, making it a potential remedy for athletes.

Objective: The objective of this systematic review is to assess the scientific evidence supporting the efficacy of curcumin in reducing muscle damage caused by sports.

Methods: A structured search in SCOPUS, Medline, and Web of Science databases was conducted in March 2023, including all available articles. The strategy involved selecting English articles without time constraints, using the search terms "curcumin" AND "Exercise-Induced Muscle Damage" (ALL(curcumin AND "Exercise-Induced Muscle Damage")). Titles and abstracts were screened to assess eligibility. Studies were chosen based on PICOS criteria, and quality was evaluated using the reliable PEDro scale. The eligibility criteria included adults without any diagnosed diseases who regularly exercise (at least three times per week) and follow a consistent pattern of curcumin intake before, during, or after exercise.

Results: The comprehensive search identified 11 relevant studies investigating the effects of curcumin supplementation in sport-simulated interventions. These studies suggest that curcumin intake may help reduce muscle symptoms associated with eccentric exercises, thereby improving pain perception. Effective use of curcumin depends on factors such as dosage, bioavailability, and timing, with post-exercise ingestion appearing to be more beneficial.

Conclusions: Curcumin demonstrates a significant potential to relieve muscle-related symptoms, especially delayed-onset muscle soreness (DOMS) that arises from eccentric exercises, thus potentially improving the well-being of those who are trained. It also appears to have the capability to lower biomarkers associated with inflammation and boost antioxidant levels. Nevertheless, for future studies, the bioavailability of curcumin must be considered, as it is a key factor in its efficacy.

Background: The regular practice of physical activity is considered a health promoter and appears to be one of the main contributors to the prevention of chronic diseases. However, the potential effects of exercise on health depending on the time of day at which it is performed have not yet been fully elucidated.

Objectives: To evaluate the effect of physical exercise (aerobic or anaerobic) and chronobiology (morning or afternoon) on the glycemic metabolism of healthy subjects.

Methods: Healthy subjects participated in aerobic or anaerobic physical exercise sessions, either in the morning or in the afternoon. Blood was drawn from the subjects before, at the end of the exercise and 2 hours after the end of the exercise. Glycemic parameters were analyzed at these time points. A general linear model test was performed after verifying the normal distribution of the raw data (as assessed by the Shapiro-Wilk test) or after a logarithmic/square root transformation, considering aerobic or anaerobic exercise and morning or afternoon exercise as independent variables.

Results: Twenty-three subjects (14 women and 9 men) were included in the study. The rate of change in glucose levels was significantly higher at the end of anaerobic exercise compared to aerobic exercise (1.19 ± 0.04 vs. 0.98 ± 0.02, respectively), with a more pronounced decrease in insulin and C-peptide levels following aerobic exercise. In addition, the increase of glucose was higher after the exercise in the morning compared with the afternoon (1.14 ± 0.03 vs. 1.03 ± 0.03, respectively).

Conclusions: The type of exercise and chronobiology influence short-term glucose metabolism.

Background: A commercial three-dimensional optical (3DO) scanning system was reported to be used in body composition assessment. However, the applicability in Chinese adults has yet to be well-studied.

Methods: This secondary analysis was based on a 16-week weight-loss clinical trial with an optional extension to 24 weeks. Waist and hip circumference and body composition were measured by 3DO scanning at each follow-up visit during the study. Bioelectrical impedance analysis (BIA) was also performed to confirm the reliability of 3DO scanning at each visit. We used Lin's concordance correlation coefficients (CCC) to evaluate the correlation between the two methods above-mentioned. Bland-Altman analysis was also performed to evaluate the agreement and potential bias between different methods.

Results: A total number of 70 Chinese adults overweight and obese (23 men and 47 women, aged 31.8 ± 5.8 years) were included in the analysis, which resulted in 350 3DO scans and corresponding 350 BIA measurements. The percent body fat, fat mass, and fat-free mass were 33.9 ± 5.4%, 26.7 ± 4.6 kg, and 50.3 ± 8.7 kg before the trial by 3DO scanning. And they were 30.5 ± 5.8%, 22.5 ± 4.7 kg, and 49.4 ± 8.3 kg after 16 weeks of the trial. Compared with BIA, 3DO scanning performed best in the assessment of fat-free mass (CCC = 0.89, 95%CI: 0.86, 0.90), then followed by fat mass (CCC = 0.76, 95%CI: 0.71, 0.80) and percent body fat (CCC = 0.70, 95%CI: 0.64, 0.75). Subgroup analysis showed that 3DO scanning and BIA correlated better in women than that in men, and correlated better in measuring fat-free mass in participants with larger body weight (BMI ≥28.0 kg/m²) than those with smaller body weight (<28.0 kg/m²).

Conclusions: 3DO scanning is an effective technology to monitor changes in body composition in Chinese adults overweight and obese. However its accuracy and reliability in different ethnicities needs further exploration.

Background: Beetroot juice (BRJ) intake has been considered a practical nutritional strategy among well-trained athletes. This study aimed to assess the effects of BRJ intake on performance, cardiorespiratory and metabolic variables during a simulated 2000-meter rowing ergometer test in well-trained master rowers.

Method: Ten well-trained male master rowers (30-48 years) participated in a randomized, double-blind, crossover design for 3 weeks. In the first week, a researcher explained all the experimental procedures to the participants. In the next two weeks, the participants were tested in 2 rowing ergometer sessions, separated from each other by a 7-day washout period. In both strictly identical sessions, the participants randomly drank BRJ or placebo (PL) 3 hours before the start of the tests. Subsequently, the participants carried out the 2000-meter rowing ergometer tests. Oxygen saturation and blood lactate measurements were performed before starting (pretest) and at the end of the test (posttest). Performance parameters and cardiorespiratory variables were recorded during the rowing ergometer test.

Results: An improvement in time trial performance was observed, with a mean difference of 4 seconds (90% confidence limits ± 3.10; p ≤ 0.05) compared to PL. Relative and absolute $\mathrm{maximaloxygenuptake}\left(\dot{V}{O}_{2max}\right)$ increased (mean difference of 2.10 mL·kg^-1·min^-1, 90% confidence limits ± 1.80; mean difference of 0.16 L·min^-1 90% confidence limits ± 0.11, respectively; p ≤ 0.05) compared to PL. No ergogenic effect was observed on ventilatory efficiency and blood lactate concentrations after BRJ intake.

Conclusion: Acute BRJ intake may improve time trial performance as well as $\dot{V}{O}_{2max}$ in well-trained master rowers. However, BRJ does not appear to improve ventilatory efficiency.

Background: The purpose of the review was to evaluate the literature exploring nutritional habits and practices in female soccer players.

Methods: The PRISMA-ScR Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews were followed. Searches of Web of Science, PubMed and Scopus databases were conducted for studies exploring the nutritional habits and practices of female soccer players.

Results: A total of 72 studies were included in the scoping review. Studies on female soccer players mainly focused on daily energy expenditure, daily energy and macronutrient intake and hydration status. A negative energy balance was consistent across studies, and the ingestion of CHO appears below the current recommendations. Female soccer players are predominately in negative energy balance, which may indicate that they are at risk of low energy availability. A high use of nutritional supplements is apparent in female soccer, whilst a large proportion of players commence training dehydrated.

Conclusions: The current findings have implications for practitioners relating to the planning, management, monitoring, and implementation of nutritional intake and training and competition schedules.

Background: The effect of low-carbohydrate high-fat dietary manipulation, such as the ketogenic diet (KD), on muscle strength assessment in resistance-training (RT) participants has focused on the one-repetition maximum test (1-RM). However, a pre-specified 1-RM value during an exercise training program disregards several confounding factors (i.e. sleep, diet, and training-induced fatigue) that affect the exerciser's "true" load and daily preparedness. We aimed to evaluate the effect of a 6-week RT program on load control-related variables in trained subjects following a KD intervention.

Methods: Fourteen resistance-trained individuals (3F, 11 M; 30.1 [6.2] years; 174.2 [7.6] cm; 75.7 [10.8] kg; BMI 24.8 [2.1] kg·m^-2) completed this single-arm repeated-measures clinical trial. Load management variables included volume load, number of repetitions, perceived exertion (RPE), movement velocity loss, and exertion index. These primary outcomes were assessed weekly before, during, and at the end of a 6-week RT program that included traditional RT exercises (bench press, femoral lying down, lat pulldown, leg extension, and back squat).

Results: There was a significant difference in RPE between weeks (p = 0.015, W = 0.19) with a slight trend in decreasing RPE. We found differences in the volume load per week (p < 0.001; W = 0.73 and p < 0.001, W = 0.81, respectively), with an increase in the last weeks. In the control of the load based on movement velocity, we did not find significant differences between weeks (p = 0.591, W = 0.06), although significant differences were found in the effort index (p = 0.026, W = 0.17).

Conclusions: A KD diet in recreational strength participants does not appear to lead to performance losses during a RT program aimed at improving body composition. However, the lack of adherence and familiarity with the ketogenic diet must be considered specially during first weeks.

Background: Due to the increase in global temperature, it is necessary to investigate solutions so that athletes competing in hot conditions can perform in optimal conditions avoiding loss of performance and health problems. Therefore, this study aims to evaluate the effect of pre-exercise glycerol supplementation during a rectangular test at ambient temperature mid (28.2ºC) on dehydration variables in international race walkers.

Methods: Eight international male race walkers (age: 28.0 years (4.4); weight: 65.6 kg (6.6); height: 180.0 cm (5.0); fat mass: 6.72% (0.66); muscle mass: 33.3 kg (3.3); VO_2MAX: 66.5 ml · kg^-1·min^-1 (1.9)) completed this randomized crossover design clinical trial. Subjects underwent two interventions: they consumed placebo (n = 8) and glycerol (n = 8) acutely, before a rectangular test where dehydration, RPE, metabolic, kinematic, and thermographic variables were analyzed before, during and after the test.

Results: After the intervention, significant differences were found between groups in body mass in favor of the placebo (Placebo: -2.23 kg vs Glycerol: -2.48 kg; p = 0.033). For other variables, no significant differences were found.

Conclusion: Therefore, pre-exercise glycerol supplementation was not able to improve any dehydration, metabolic, kinematic, or thermographic variables during a rectangular test at temperature mid in international race walkers. Possibly, a higher environmental temperature could have generated a higher metabolic and thermoregulatory stress, generating differences between groups like other previous scientific evidence.