Journal of the International Society of Sports Nutrition最新文献

Background: Coffee is one of the most widely consumed beverages worldwide, with ongoing debate regarding its potential benefits and drawbacks for human health, particularly sleep quality. Simultaneously, dietary composition-especially a predominantly plant-based diet-has been linked to better health outcomes. This study aimed to investigate how coffee intake and dominant dietary components relate to sleep quality in physically active individuals, with consideration of additional lifestyle factors such as stress and emotional well-being.

Methods: A cross-sectional survey was administered online and via QR codes displayed in sports facilities. Physically active adults (N = 392) completed a standardized questionnaire assessing sleep quality, stress, physical activity, and demographic data. Factor analysis identified underlying dimensions of interest, which were then used in K-Means clustering to group participants with similar response patterns. Statistical analyses, including the Kruskal-Wallis test and Dunn's post-hoc comparisons, determined differences in dietary and coffee consumption habits across factors and clusters.

Results: Four factors emerged from the analysis: Stress, Health, Relaxation, and Emotional Well-being. Higher stress levels strongly correlated with poor sleep quality, while coffee consumption alone was not statistically linked to stress or sleep problems. Respondents who consumed more than two cups of coffee daily often clustered into groups reporting higher health and emotional well-being. A predominantly plant-based diet was significantly associated with better overall health scores and lower stress. Clustering analysis revealed that participants with the healthiest behaviors (Cluster 2) tended to follow plant-rich diets and reported lower stress levels and better sleep outcomes.

Conclusion: In a physically active population, stress appears to be a more robust predictor of poor sleep quality than coffee consumption. Moderate coffee intake may even coincide with higher health and emotional well-being scores. The findings emphasize that coffee consumption does not adversely affect sleep quality, and in fact has a positive effect on emotional wellbeing and health.

Background: Competitive sports and sports nutrition, popular among amateur athletes aiming for a lean physique, have limited research on gut microbiota.

Methods: We conducted a 46-week study to analyze the consequences of fat loss and diet restrictions in 23 fitness athletes who prepared for a physique competition. Body composition, dietary intakes, serum cytokines and chemokines, and fecal samples were analyzed.

Results: Fat loss through caloric restriction and aerobic exercise led to an increased phylogenetic diversity of gut microbiota and changes in the composition of gut microbiota, with Faecalibacterium, Lachnospiraceae, Bacteroides, and Intestinimonas showing altered abundances. Fat loss also changed the predicted microbial functions responsible for the metabolism of carbohydrates and amino acids. Consumption of energy, carbohydrates, fiber, vitamins and minerals, and various fatty acids decreased during the preparation for the competition, which was partly associated with changes in gut microbiota. Several cytokine levels decreased (IL1a, IL1b, IL10, and TFNα), and certain chemokine levels increased (GROa and RANTES). During the 23-week regain period after the competition, gut microbiota showed signs of recovery, with increased diversity compared to pre- and post-competition measurements. Most taxonomic changes returned to their baseline levels after the regain period.

Conclusions: The study highlights the dynamic nature of gut microbiota and its response to fat loss and regain in non-obese fitness/physique competitors and provides novel insights into how competitive sports and sports nutrition can influence the gut ecosystem.

Background: Compared to the general population, athletes experience high energy expenditures requiring increased energy and macronutrient intakes to sustain training and optimize performance. While the International Olympic Committee (IOC) and International Society for Sports Nutrition (ISSN) have established recommendations for nutrient intakes, many athletes do not meet the recommended daily allowance (RDA) for the general population, and sport and sex-specific differences are not well documented. Exploration of within-day energy balance (WDEB) shows athletes may achieve energy balance by the end of the day but may present with poor WDEB. Data support that female athletes are at greater risk of nutrient deficiencies than their male counterparts, and it is unclear whether swimmers meet sport-specific nutrient intake and timing recommendations. Following our previous WDEB analysis, the purpose of this investigation was to assess dietary macronutrient intake as related to RDAs (USDA and IOC/ISSN), within-day macronutrient timing, and associated sex differences in swimmers.

Methods: In elite male and female swimmers (n = 25; 18-22 yr), we assessed energy intake (EI), total daily energy expenditure (TDEE), macronutrient intake (fat (FAT), protein (PRO), carbohydrate (CHO)) and timing during heavy training. Frequency analysis was utilized to determine the number of athletes meeting general and athlete-specific RDAs. Repeated-measures ANOVA was used to assess nutrient timing across sex groups.

Results: When compared to IOC/ISSN daily recommendations, only 6/25 swimmers met FAT intake, 7/25 met CHO intake, and 24/25 met PRO intake IOC/ISSN daily recommendations.Males had greater EI and TDEE compared to females (p < 0.05). PRO consumption (% of EI) was a larger percentage of total intake in male vs females (28 ± 5% vs 23 ± 3%; F = 2.996; p = 0.014). No swimmers met CHO recommendations (g⋅kg^-1) pre- or during exercise for the first daily training session. 13/25 met pre-exercise CHO recommendations, while 6/25 and 11/25 met during and post-exercise CHO recommendations for the second training session. Repeated measures ANOVA revealed effects of sex and time on intake (g⋅kg LBM^-1⋅hr^-1) for FAT (Sex; F = 5.659, p = 0.26; time; F = 12.068, p = 0.006) and PRO (Sex; F = 6.719, p = 0.016; time; F = 13.177, p = 0.011). There was a significant sex*time interaction for CHO consumption (F = 6.520, p = 0.017).

Conclusion: The results from this study demonstrate significant sex-differences, indicating that most swimmers meet athlete-specific recommendations for PRO, but not CHO or FAT intake. CHO timing for pre-, during, and post-exercise was met by only 52% swimmers. Results suggest that swimmers should prioritize CHO intake, emphasized around and during training bouts.

Background: The body composition of National Collegiate Athletic Association (NCAA) athletes is well documented but no such data exist for university club sports athletes. Additionally, the majority of norms for NCAA athletes were created from individual methods requiring assumptions.

Objective: This study used a four-component (4C) model to measure the body composition of university club sports athletes.

Methods: Data were collected on club athletes participating in baseball, climbing, cycling, figure skating, gymnastics, ice hockey, lacrosse, pickleball, powerlifting, racquetball, rodeo, rugby, soccer, swimming, ultimate, and volleyball. The 4C model consisted of body volume, total body water, and bone mineral content measured by air displacement plethysmography, bioimpedance spectroscopy, and dual-energy x-ray absorptiometry, respectively. Percentile ranks were created for body fat percentage (%BF) and fat-free mass index (FFMI). Mean differences across teams were quantified with Cohen's d.

Results: In total, 225 athletes (137 men, 88 women) completed data collection. Athletes varied in competitive experience (1 to 22 y) and body mass index (16.9 to 36.4 kg·m^-2). The density of the FFM was significantly greater than the assumed value of 1.100 g·cm^-3 for both men (p = .043) and women (p = .011). The %BF ranged from 4.9% to 35.7% (14.3 ± 5.8% BF) for men and from 15.5% to 42.8% (25.2 ± 6.0% BF) for women. FFMI ranged from 15.6 kg·m^-2 to 26.8 kg·m^-2 (30.0 kg·m^-2 outlier removed) for men and from 14.1 kg·m^-2 to 22.6 kg·m^-2 for women. Differences across sports in %BF and FFMI were considered large-sized effects (d ≥ 0.80) for both men and women. Weight-sensitive sports (e.g. cycling and climbing) had the lightest athletes and were among the leanest, whereas power athletes (e.g. powerlifting and rugby) were among the heaviest athletes and had the highest FFMI.

Conclusions: Differences in %BF and FFMI are evident across sports. Due to the small sample size, use caution when interpreting the data as reference values for club sports athletes.

Purpose: Rugby sevens is a high-intensity contact sport often played in two-day tournaments. Caffeine is widely used by rugby players for its performance-enhancing effects. This study aimed to investigate the impact of caffeine supplementation on various performance metrics, including distance covered at different speeds, acceleration, deceleration, collisions, and repeated high-intensity efforts across four matches over two consecutive days in collegiate male rugby sevens players. Reactive agility, a key performance attribute in rugby sevens, was also assessed before each match.

Methods: A position-matched, double-blind, randomized crossover design was employed, with six male collegiate rugby players (mean height: 1.78 ± 0.09 m, mean weight: 81.3 ± 9.2 kg, mean age: 21.5 ± 0.8 years) participating in two trials. Each trial consisted of a two-day tournament, with two matches per day. Performance was monitored using global positioning system units to track distance covered in various speed zones, as well as total distance, frequency of acceleration, deceleration, collisions, and repeated high-intensity efforts.

Results: The results indicated that in the placebo trial, participants covered significantly more distance at a walking pace (0-6 km/h) in match 4 compared to match 3 (match 3: 480.3 ± 32.7 m; match 4: 629.4 ± 21.3 m, p < 0.001, d = 0.117). In the caffeine trial, players covered significantly more distance at a jogging pace (6-12 km/h) in match 4 compared to the placebo trial (caffeine: 405.9 ± 9.8 m; placebo: 303.6 ± 20.2 m, p = 0.015, d = 1.693). Reactive agility was significantly better in the caffeine trial before match 3 (caffeine trial: 1.80 ± 0.17 s; placebo trial: 2.07 ± 0.18 s, p = 0.038, d = 0.858).

Conclusions: Caffeine supplementation at 3 mg/kg may increase jogging and reduce walking and standing in the final match of a two-day rugby sevens tournament, while also improving reactive agility on the second day. This suggests that by mitigating fatigue in the later stages of the tournament, caffeine allowed players to shift from low-intensity activities to higher-intensity efforts. These adjustments may improve both offensive and defensive performance during rugby sevens matches. Therefore, rugby sevens players could benefit from taking caffeine supplements in the later stages of 2-day tournaments to optimize their performance.

Background: Athletes' oral health can impact overall well-being and sports performance. This study aimed to evaluate the interactions between eating habits and oral health of 120 young athletes as compared to 30 age-matched individuals not practicing sports based on a questionnaire and the analysis of saliva.

Methods: One hundred twenty subjects practicing various sports activities (test group) and 30 subjects not practicing sports (control group) were selected. A self-administered questionnaire was used to obtain personal data, hours and frequency of weekly training, complete pathological history, history of hard and soft tissues of the oral cavity, family history, and oral hygiene practices. The eating habits of the young participants were analyzed by investigating the number of daily meals; use and frequency in sports practice of supplements/energy drinks, fruit/juices, snacks, chocolate; daily diet; and differences between usual diet and pre-competition diet. At baseline (T0), each participant was clinically assessed for the determination of the number of decayed, missing, and filled teeth (DMFT), Silness & Löe Plaque Index (PI), and the Löe & Silness Gingival Index (GI) and qualitative analysis for the presence/absence of stains and dental erosions. At T0, before (T1) and after training sessions (T2), saliva was collected to determine resting pH, Streptococcus mutans, and Lactobacillus spp counts.

Results: Test groups were trained more than 2 h, 5 times a week. Soccer players and skiers had a high percentage of caries; water polo players demonstrated the highest percentage of erosions and dental stains. Salivary resting pH showed statistically different values in three different observations between the groups. S. mutans was harbored by 60% of soccer and 70% of water polo players, while Lactobacillus spp in 43.33% of the swimmers and soccer players. Combining all the 56 variables including the clinical examination, self-reported parameters, and salivary analysis, we have identified water polo players as a distinct at-risk group for developing dental defects, expressed as an aggregate disease score. In particular, we have found that energy snacks/chocolate intake is strongly associated with ratio of S. mutans/Lactobacillus spp and that S. mutans is linked to dental defects (R = 0.88). Linear regression analysis indicates that energy snacks/chocolate intake in the study population represents a strong driver for oral dysbiosis and dental disease.

Conclusions: Our study clearly shows that athletes should follow a balanced diet that not only satisfies their nutritional needs but also avoids oral dysbiosis and subsequent dental damage.

Background: Taekwondo is a complex martial art that requires speed, balance, agility, and endurance. This study aims to examine the effects of nitrate and L-arginine supplementation on acute aerobic and anaerobic performance, balance, agility, and recovery in elite taekwondo athletes.

Method: This study was conducted as a double-blind, randomized, crossover study with the participation of 15 experienced taekwondo athletes aged 19.06 ± 0.96 years and 8.93 ± 1.27 years of training experience. Participants visited the laboratory a total of nine times, including a practice session and anthropometric measurements. These visits consisted of eight experimental sessions conducted at 72-hour intervals. The experimental sessions were conducted with nitrate, L-arginine, and a combination of both supplements (NIT*L-ARG) and placebo. Nitrate supplementation was provided by homogenizing fresh spinach (837.40 mg/kg), while L-ARG was given as a single dose of 6 g in powder form three hours before exercise.

Results: NIT*L-ARG supplementation significantly improved the anaerobic performance of athletes in Wingate peak power and peak power (w/kg) compared to placebo and in mean power compared to NIT, L-ARG, and PLA. In addition, NIT*L-ARG supplementation significantly improved blood lactate levels and agility performance immediately after Wingate and Shuttle run tests.

Conclusion: The combined intake of NIT*L-ARG was found to be effective in improving aerobic, anaerobic, and agility performances as well as fatigue levels of athletes. It was determined that taking NIT and L-ARG supplements alone contributed to the improvement of improving athletes' performance in Wingate mean power values and subsequent fatigue level compared to PLA.

Background: Research has shown air displacement plethysmography (ADP) to be a valid and reliable alternative to dual-energy X-ray absorptiometry (DXA) in the general population; however, its validity and reliability indicate conflicting evidence in an athletic population. The purpose of this study is to develop a novel estimation equation using body density obtained from ADP in an athletic population to assess body fat percent (BF%) more accurately.

Methods: One hundred and thirty (males, n = 69; females, n = 61) National Collegiate Athletic Association Division I athletes participated in this study. Thirty athletes were randomly withheld for the hold-out sample, and the remaining 100 athletes were used in the development of the equation. Body composition was evaluated using ADP and DXA. Linear regression was used to develop a new prediction equation (Equation 1) with body density (ADP) as the independent variable and BF% (DXA) as the dependent variable. Repeated measures analysis of variance was used to identify differences between ADP-Brozek, DXA, and Equation 1. Interclass correlation coefficients (ICCs) were assessed to evaluate the reliability of the equation.

Results: Significance was set to p < 0.05. Linear regression was conducted to create Equation 1, which explained 90.5% of the variance. ADP-Brozek reported lower BF% than Equation 1 (p < 0.001) in the development and hold-out samples; however, BF% from Equation 1 and DXA were not different from each other (p = 0.999). ICCs were strong in both samples (original sample: ICC = 0.975, p < 0.001; hold-out sample: ICC = 0.964, p < 0.001).

Conclusion: The newly proposed equation may be used with ADP measurements to interpret BF% in an athletic population.

Background: Caffeine, widely used as an ergogenic aid, has been extensively studied regarding its dosage and timing of ingestion. However, the impact of different administration methods on caffeine's performance-enhancing effects remains relatively underexplored. This study compared the effects of caffeine administered via chewing gum versus capsules on maximal strength, muscular power, and side effects during bench press and back squat exercises.

Methods: Sixteen resistance-trained males participated in a double-blind, randomized trial, ingesting either a 4 mg/kg caffeine capsule (CC) or placebo capsule (PC) one hour before testing, or a 4 mg/kg caffeinated gum (CG) (4 mg/kg) or placebo gum (PG) five minutes prior. Assessments including one-repetition maximum (1RM) and muscular power at 25%, 50%, 75%, and 90%1RM for bench press and back squat.

Results: Caffeine increased 1RM (+2.1-5.0%) and muscular power (+6.1-20.0%) in both the bench press and back squat compared to placebo (all p < 0.05). However, no significant differences were observed between CC and CG for maximal strength or muscular power (all p > 0.05). Furthermore, CG was associated with fewer reports of gastrointestinal discomfort (12.5% vs. 37.5%) immediately post-exercise and tachycardia/heart palpitations (0% vs. 25.0%) at 24 hours compared to CC (all p < 0.05).

Conclusion: Caffeinated gum (4 mg/kg) produced ergogenic effects comparable to capsules in enhancing maximal strength and muscular power during bench press and back squat exercises, with fewer side effects in resistance-trained men.

Background: Impaired fat oxidation is linked to cardiometabolic risk. Maximal fat oxidation rate (MFO) reflects metabolic flexibility and is influenced by lean mass, muscle strength, muscle quality - defined as the ratio of strength to mass - and cardiorespiratory fitness. The relationship between these factors and fat oxidation is not fully understood. The aim is to analyze the associations of lean-mass, muscle strength and quality with fat oxidation parameters in young adults, considering the mediating role of VO₂max.

Methods: A cross-sectional observational study. Eighty-one adults (50 males, 31 females; age 22.8 ± 4.4, BMI 25.70 ± 5.75, lean-mass 54.19 ± 8.78, fat-mass 18.66 ± 11.32) Body composition assessment by bioimpedance determine fat and lean-mass. Indirect calorimetry at rest and exercise was used for the calculation of fat oxidation. An incremental exercise protocol in a cycle ergometer with two consecutive phases was performed. The first to determine MFO consisted of 3 min steps of 15W increments with a cadence of 60rpm. The test was stopped when RQ ≥ 1. After 5 min rest, a phase to detect VO₂max began with steps of 15W/min until exhaustion. Muscular strength was assessed by handgrip dynamometry and the standing longitudinal jump test. A strength cluster was calculated with handgrip and long jump adjusted by sex and age. Data were analyzed using multiple linear regression and mediation analyses.

Results: Total lean-mass and leg lean-mass were not associated with MFO. Long jump, relativized by lean-mass and by leg lean-mass have a standardized indirect effect on MFO of 0.50, CI: 0.32-0.70, on MFO/lean-mass 0.43, CI:0.27-0.60 and MFO/leg lean-mass 0.44, CI: 0.30-0.06, which VO₂max mediated, VO₂max/lean-mass and VO₂max/leg lean-mass, respectively (all p < 0.01). The handgrip/arm lean-mass had an indirect effect of 0.25 (CI: 0.12-0.38) on MFO/leg lean-mass, with VO₂max/leg lean-mass as the mediator (p < 0.01). The Cluster/lean-mass and Cluster/Extremities lean-mass have a standardized indirect effect on MFO/lean-mass (0.34, CI: 0.20-0.48) and MFO/leg lean-mass (0.44, CI: 0.28-0.60), mediated by VO2max/lean-mass and VO2max/leg lean-mass (p < 0.01).

Conclusions: Muscular strength and quality have an indirect effect on MFO mediated by VO₂max. These findings suggest the importance of muscle quality on MFO.