Journal of the International Society of Sports Nutrition最新文献

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: 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: 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.

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: Caffeine, identified as a central nervous system stimulant in foods, beverages (coffee, tea, chocolate), and medications, has been focused on its ergogenic properties, enhancing physical performance. The aim of this study was to investigate the association between the caffeine intake (from coffee) and fat-free mass index (FFMI).

Materials and methods: We carried out a cohort study that included 3,466 women and 3,145 men aged ≥20 years who were intaking caffeine. Caffeine intake from coffee were obtained from two 24-hour dietary recall interviews. The FFMI was calculated as FFM (kg) divided by height in m². The caffeine intake was classified into quartiles and combined into 4 groups. Multiple linear regression model analysis and multiple logistic regression model analysis were used to assess associations between the caffeine and FFMI adjusted for potential confounders.

Results: Among the 2,427 participants, males accounted for 52.4%, and females 47.6%. In multiple linear regression model, Model 1 (unadjusted Model (p = 0.041)) and Model 2 (adjusted for age, race, and BMI (p = 0.006)) in women showed a significant relationship between caffeine intake and FFMI. In multivariable models, caffeine intake and FFMI were significantly different (p < 0.05). In sex subgroups, among females, each quartile of caffeine intake was positively correlated with FFMI levels in the average FFMI group in Model 3 (p < 0.001). In age subgroups, each quartile of caffeine intake was positively correlated with FFMI levels in the average FFMI group in Model 3 for individuals aged 20-40 (p = 0.039) and those aged above 40 (p = 0.016). In drinking status subgroups, if they drunk alcohol, each quartile was positively correlated with FFMI levels in the average FFMI group in Model 3 (p < 0.001).

Conclusion: Caffeine intake was mainly positively associated with FFMI, especially in women with above levels of FFMI. Longitudinal studies and randomized controlled trials are needed to establish causality and provide evidence-based recommendations regarding caffeine intake to optimize muscle health.

Objective: The aim of this study was to identify the key regulatory mechanisms of cartilage injury and osteoporosis through bioinformatics methods, and to provide a new theoretical basis and molecular targets for the diagnosis and treatment of the disease.

Methods: Microarray data for cartilage injury (GSE129147) and osteoporosis (GSE230665) were first downloaded from the GEO database. Differential expression analysis was applied to identify genes that were significantly up-or down-regulated in the cartilage injury and osteoporosis samples. These genes were subjected to GO enrichment analysis and KEGG pathway analysis. In addition, we employed SVA and RRA methods to merge the two sets of data, eliminating batch effects and enhancing the statistical power of the analysis. Through WGCNA, we identified gene modules that were closely associated with disease phenotypes and then screened for key genes that intersected with differentially expressed genes. The diagnostic value of these genes as potential biomarkers was evaluated by ROC analysis. Moreover, we performed an immune infiltration analysis to explore the correlation between these core genes and immune cell infiltration.

Results: We performed GO enrichment analysis and KEGG pathway analysis of genes significantly up-or down-regulated in cartilage injury and osteoporosis samples. Important biological processes, cellular components and molecular functions, and key metabolic or signaling pathways associated with osteoporosis and cartilage injury were identified. Through WGCNA, we identified gene modules that were closely associated with the disease phenotype, from which we then screened for key genes that intersected with differentially expressed genes. Ultimately, we focused on two identified core genes, COL1A1 and TNFRSF12A, and assessed the diagnostic value of these genes as potential biomarkers by ROC analysis. Meanwhile, GSVA provided an in-depth view of the role of these genes in disease-specific biological pathways. Immune infiltration analysis further revealed the possible key role of COL1A1 and TNFRSF12A in regulating immune cell infiltration in osteoporosis and cartilage injury.

Conclusion: COL1A1 and TNFRSF12A as key regulatory molecules in osteoporosis and cartilage injury.

Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of the literature surrounding the effects of long-chain omega-3 polyunsaturated fatty acid (ω-3 PUFA) supplementation on exercise performance, recovery, and brain health. This position stand is intended to provide a scientific foundation for athletes, dietitians, trainers, and other practitioners regarding the effects of supplemental ω-3 PUFA in healthy and athletic populations. The following conclusions represent the official position of the ISSN: Athletes may be at a higher risk for ω-3 PUFA insufficiency.Diets rich in ω-3 PUFA, including supplements, are effective strategies for increasing ω-3 PUFA levels.ω-3 PUFA supplementation, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has been shown to enhance endurance capacity and cardiovascular function during aerobic-type exercise.ω-3 PUFA supplementation may not confer a muscle hypertrophic benefit in young adults.ω-3 PUFA supplementation in combination with resistance training may improve strength in a dose- and duration-dependent manner.ω-3 PUFA supplementation may decrease subjective measures of muscle soreness following intense exercise.ω-3 PUFA supplementation can positively affect various immune cell responses in athletic populations.Prophylactic ω-3 PUFA supplementation may offer neuroprotective benefits in athletes exposed to repeated head impacts.ω-3 PUFA supplementation is associated with improved sleep quality.ω-3 PUFA are classified as prebiotics; however, studies on the gut microbiome and gut health in athletes are currently lacking.

Background: Effective nutritional support is essential for maintaining good performance during exercise. Taste and olfaction are key senses for food intake, and understanding how their sensitivities change during exercise is important for effective nutritional support. However, the effects of exercise on taste and odor sensitivities remain unclear. This study aimed to investigate changes in taste and odor sensitivities during repeated endurance exercise using a bicycle ergometer.

Methods: A total of 20 women (mean age; 21.6 ± 0.2 years) participated in the study, completing four 60-minute segments, each comprising 50 minutes of bicycle ergometer exercise at an exercise intensity of 60% heart rate reserve and a 10-minute sensory test. The sensory tests were conducted five times in total: after each exercise segment and once before exercise as a control. Four concentrations (×0.5, ×0.75, ×1, and × 1.25) of a commercially available isotonic beverage were used as taste samples, and the subjects evaluated the taste intensity, preference, and odor intensity. Four types of food odorants were used as odor samples, and the subjects rated their preference. The subjects also reported their perceived fatigue levels during the taste and odor tests. Fatigue levels and taste intensity were rated using a 100-mm visual analogue scale, and taste and odor preferences and odor intensity were evaluated using a scoring method.

Results: The degree of physical fatigue significantly increased with each successive bicycle exercise segment. The taste intensity and preference for beverages with higher concentrations increased as the number of exercise segments increased, showing a significant increase in taste intensity for the × 1.25 solution in the final segment compared with before the tests. On the other hand, no significant effect was observed on the perceived odor intensity of the isotonic beverages. Similarly, there was no significant effect on the preference for odor samples due to repeated exercise.

Conclusions: These results suggest that taste sensitivity may change with prolonged exercise. Additionally, since odor intensity and preference were not significantly affected by repeated exercise, odor sensitivity may be less impacted by exercise than taste sensitivity.

Creatine monohydrate supplementation (CrM) is a safe and effective intervention for improving certain aspects of sport, exercise performance, and health across the lifespan. Despite its evidence-based pedigree, several questions and misconceptions about CrM remain. To initially address some of these concerns, our group published a narrative review in 2021 discussing the scientific evidence as to whether CrM leads to water retention and fat accumulation, is a steroid, causes hair loss, dehydration or muscle cramping, adversely affects renal and liver function, and if CrM is safe and/or effective for children, adolescents, biological females, and older adults. As a follow-up, the purpose of this paper is to evaluate additional questions and misconceptions about CrM. These include but are not limited to: 1. Can CrM provide muscle benefits without exercise? 2. Does the timing of CrM really matter? 3. Does the addition of other compounds with CrM enhance its effectiveness? 4. Does CrM and caffeine oppose each other? 5. Does CrM increase the rates of muscle protein synthesis or breakdown? 6. Is CrM an anti-inflammatory intervention? 7. Can CrM increase recovery following injury, surgery, and/or immobilization? 8. Does CrM cause cancer? 9. Will CrM increase urine production? 10. Does CrM influence blood pressure? 11. Is CrM safe to consume during pregnancy? 12. Does CrM enhance performance in adolescents? 13. Does CrM adversely affect male fertility? 14. Does the brain require a higher dose of CrM than skeletal muscle? 15. Can CrM attenuate symptoms of sleep deprivation? 16. Will CrM reduce the severity of and/or improve recovery from traumatic brain injury? Similar to our 2021 paper, an international team of creatine research experts was formed to perform a narrative review of the literature regarding CrM to formulate evidence-based responses to the aforementioned misconceptions involving CrM.