Journal of the International Society of Sports Nutrition最新文献

Introduction: Established guidelines recommend carbohydrate-rich diets to optimize performance in endurance sports. However, alternative dietary strategies, such as the low-arbohydrate and high-fat (LCHF) diet, have gained increasing attention due to their potential to influence metabolic flexibility and endurance performance outcomes. In this study, we aim to investigate the combined effects of a LCHF diet, along with low glycemic index (LOW-GI) and high glycemic index (HIGH-GI) diets, in conjunction with regular endurance exercise, on the metabolomic profiles of recreational runners. The classification into LOW-GI and HIGH-GI groups is based on the premise that metabolic regulation, particularly insulin response and glucose metabolism, differs significantly between the consumption of high-glycemic and low-glycemic foods.

Methods: The participants (n = 49, 28 ± 4 years, BMI: 24.2 ± 2.8 kg/m2, VO2 peak: 56 ± 8 ml/min/kg) were randomly allocated to a LOW-GI (n = 16), a HIGH-GI (n = 16) or a LCHF (n = 17) diet for 10 weeks and the same endurance training intervention. Fasting plasma samples were collected both pre- and post-intervention and were prepared for non-targeted metabolomic analysis using liquid chromatography coupled to high-resolution mass spectrometry.

Results: The LCHF diet had a considerable impact on plasma lipids, whereas the respective effects in the LOW-GI and HIGH-GI groups were less pronounced. Specifically, 179 up- or down-regulated metabolites were identified in the LCHF group, 111 in the LOW-GI group, and 139 in the HIGH-GI group. Phospholipids and sphingolipids were found to be the most prominent metabolites in the samples. Furthermore, the regulation of glycerolipids, carnitine, amino acids, and carbon acids exhibited differential patterns across the groups.

Discussion: There is evidence to suggest that the LCHF diet enhances fat metabolism, as indicated by increased levels of carnitine and ketone bodies, as well as a downregulation of amino acids. Conversely, the presence of specific carbon acids might diminish carbohydrate metabolism and impair endurance performance. In contrast, the LOW-GI group may have demonstrated augmented metabolic flexibility due to the upregulations of both carnitines and carbon acids in the samples. The elevated glycerolipids content in the HIGH-GI group suggests a potential reduction in fatty acid oxidation due to hyperinsulinemia.

Background: This study aimed to investigate the current status and perceptions of nutrition education among sports majors and workers in Korea to provide information that can be utilized in educational curriculums of universities and other external institutions for sports nutrition education.

Methods: This study included Korean adults aged over 19 years who majored in physical education at a university. The questionnaire consisted of questions regarding demographic characteristics (10 questions), nutritional awareness (20 questions), and the General Nutrition Knowledge Questionnaire (GNKQ, 88 questions). This survey was conducted entirely online using simple random sampling, and 706 responses were included in the final data analysis. An independent sample t-test and one-way ANOVA were conducted to confirm group differences. Post hoc pairwise comparisons with a Tukey adjustment were conducted. The statistical significance level for all data was set at p < 0.05.

Results: Approximately 42% of the participants completed nutrition classes at the university and 19.4% at other institutions. The assessment of their nutritional knowledge level was 3.06   ±   1.08 points (p < 0.001) on a 5-point Likert scale, with participants who had completed nutrition classes scoring higher (p < 0.001).The GNKQ also found that participants who received nutrition classes scored higher in all sections, including the total scores (total score, p = 0.011; one section, p = 0.030; three sections, p < 0.001).

Conclusion: Nutrition is a crucial aspect that cannot be excluded from physical education. Therefore, government and university institutions must increase lecture hours and hands-on opportunities by incorporating diverse educational curricula in physical education-related departments. This approach will help create a safer and more systematic sports environment and positively impact healthcare policies.

Background: Pilates is a popular type of exercise, aimed at improving core muscle strength and endurance, core stability, and joint flexibility through a variety of whole-body exercises. Research has shown that Pilates improves body composition, muscle endurance, and joint flexibility. Adequate protein intake is a key factor in supporting the adaptive response of skeletal muscle to exercise training. However, whether protein supplementation augments the adaptations to Pilates training remains unknown. Thus, the aim of the present study was to investigate the effects of protein supplementation during Pilates training on body composition, core muscle endurance, and joint flexibility in trained women.

Methods: Nineteen Pilates-trained women (31 ± 9 y) performed 10 weeks of Pilates training using the Reformer and Cadillac apparatuses, at least 2 times per week. Participants were randomly allocated to either a placebo (n = 10) or protein supplementation group (n = 9) in a quadruple-blind (participants, intervention providers, investigators, and outcome assessors) design. Participants received 0.6 g of maltodextrin or whey protein per kg body weight daily, respectively. Habitual dietary intake was monitored throughout the study. Before and after the intervention, anthropometric measures (body weight, body mass index, waist and hip circumferences), body composition [through full-scan dual-energy X-ray absorptiometry (DXA) and multifrequency bioelectrical impedance analysis (BIA)], core muscle endurance (through the McGill's torso muscular endurance test battery), and joint flexibility (through the sit-and-reach test) were assessed. Data were analyzed by 2-way ANOVA (supplement × time) with repeated measures on time. Common DXA and BIA variables (whole-body fat and lean mass) were compared through paired Student's t tests and subjected to Pearson's correlation analysis. The level of statistical significance was set at α = 0.05.

Results: Participants received, on average, 1.3 g protein/kg body weight/day from their habitual diet. After 10 weeks of Pilates training and regardless of supplementation, body fat (assessed by BIA) and hip circumference decreased; lean mass, total water, and extracellular water (by BIA) increased; and arm lean mass, trunk bone mineral content, and trunk bone area (by DXA) increased (all p < 0.05). The common BIA and DXA variables were highly correlated (r > 0.78, p < 0.001) and did not differ pre-intervention (p > 0.1), although they differed post-intervention (p < 0.001), with BIA overestimating lean mass compared with DXA. Core muscle endurance and joint flexibility increased with training (p < 0.05), with no effect of supplementation.

Conclusion: Ten weeks of Pilates training improved core muscle endurance, joint flexibility, and aspects of body composition in healthy trained women,

Background: Low energy availability (LEA) can negatively impact athletes' physiological function and performance. This study aims to examine the prevalence of LEA in Chinese female combat athletes and monitor changes in physiological function and performance during the pre-competition period.

Method: We assessed the incidence of low energy availability (LEA) and eating disorder (ED) risks in 84 female combat athletes (judo, freestyle wrestling, and sanda) from Beijing using the Low Energy Availability in Females Questionnaire (LEAF-Q) and the Eating Disorder Examination Questionnaire (EDE-Q). From this group, 11 judo athletes who were preparing for competition were selected and divided into a low energy availability (LEA) group and a non-LEA group based on their energy availability levels. Dietary intake, training energy expenditure, body composition, resting metabolic rate, blood markers, and special judo fitness tests were monitored at 4 weeks, 2 weeks, and 0 weeks before the competition.

Results: Among the 84 athletes, 45.2% of athletes (n = 38) were at increased risk of LEA, and 21.4% of athletes (n = 18) were classified as high in eating disorder risk. There were no significant differences in LEA and ED risk between elite and recreational athletes. Among the 11 athletes preparing for competition, 6 athletes (45.5%) were in a state of LEA at the initial stage (4 weeks before the competition), and by the competition week, all 11 athletes exhibited LEA. Additionally, athletes in the LEA group experienced significant reductions in VO₂ and resting metabolic rate at 0 week of the competition compared to 4 weeks prior (p < 0.05). Thyroid function indicators and IGF-1 levels of LEA group also significantly decreased (p < 0.05). After completing the four-week pre-competition weight loss, heart rate recovery during the special judo fitness test improved significantly in both the LEA and non-LEA groups (p < 0.05).

Conclusion: The current study identified a risk of LEA among Chinese female combat sport athletes, with no significant difference in the prevalence of LEA between elite and recreational athletes. It is essential for Chinese coaches and sports medicine staff to implement LEA-related nutritional education across all performance levels. Moreover, preventive measures during training are recommended to mitigate the impact of LEA on physiological function during the pre-competition weight loss phase.

Background/objective: Dietary restriction or exercise regimens can promote weight loss or physical fitness among patients with obesity. However, intervention-associated adverse effects may impede patients' motivation to participate in dietary/exercise interventions. We examined the effects of time restricted eating (TRE) with or without resistance training (RT) on body composition, mood profile, and sleep quality in young college adults with overweight or obesity.

Methods: Fifty-four young college students with overweight/obesity were randomized into control (CON), TRE, RT, and TRE plus RT (TRE+RT) trials. The TRE trials restricted to an eating window of 10-hour/day for 8-week. The RT trials performed supervised resistance exercise, while the control trial maintained a regular lifestyle. Changes in body composition variables, blood pressure, mood status, and sleep quality were measured before and after the intervention.

Results: TRE intervention alone or in combination with RT significantly (p < 0.01) decreased body weight (>2 kg) and BMI (~1 kg/m²) in adults with overweight/obesity. Both RT alone and combined with TRE substantially decreased fat mass by 1.1 ± 0.5 and 3.2 ± 0.4 kg, respectively. The decreased fat mass was greater in the combination trial than in the RT trial, whereas TRE alone had no effect. In contrast, fat-free mass was significantly (p < 0.01) decreased with TRE (-2.3 ± 06 kg), increased with RT (1.6 ± 0.3 kg), and was stably maintained with combination interventions. The reduced waist and hip circumferences in the TRE (p < 0.01) were similar to those in the TRE+RT trials, however, RT alone had no effect. Time and group interaction showed a large effect size (partial eta squared) for all body composition variables. In addition, RT with or without TRE notably decreased diastolic blood pressure (RT: -5.5 ± 1.9 mmHg, TRE+RT: -4.1 ± 1.5 mmHg, p < 0.05). Mild anxiety levels at baseline in RT (4.8 ± 2.6) and TRE+RT (4.1 ± 3) trials were found to be normal at postintervention in TRE+RT (3.6 ± 1.7) but not in RT (5.6 ± 3.5). No depression or stress was recorded among the participants during the intervention. The reported poor sleep quality among participants at baseline was significantly improved with RT (4.8 ± 2.9; p < 0.05), and tended to improve with TRE+RT interventions (4.5 ± 1.9).

Conclusions: 10-hour TRE is beneficial for weight/fat loss without affecting mood status. However, TRE combined with RT might be more effective for weight/fat loss, maintaining muscle mass, and good quality of sleep among young adults with overweight or obesity.

Background: The interactive effect of mental fatigue and caffeine consumption on sport performance is not clear. This study aimed to investigate the impact of mental fatigue and caffeine gum consumption on power and skill performance in recreationally trained male basketball players.

Methods: A randomized, double-blind, crossover design was used, with twenty male participants (age: 16.7 ± 0.86 years, body mass: 79.6 ± 8.2 kg, height: 183.2 ± 8.6 cm, training experience ≥ 3 years). Participants completed four testing sessions under the following conditions: (1) no mental fatigue with placebo gum, (2) mental fatigue with placebo gum, (3) no mental fatigue with caffeine gum, and (4) mental fatigue with caffeine gum. The sessions were separated by one week. Mental fatigue was induced through a 30-minute Stroop task, and caffeine gum (50 mg of caffeine per piece) was administered 15 minutes before performance testing. Power and skill performance were assessed via vertical jump height, V-CUT dribbling test, medicine ball throw, and stationary two-point shooting, with three attempts per test.

Results: Mental fatigue significantly increased time to react for congruent name and color (Z = 3.9, p < 0.001) and incongruent name and color (Z = 3.9, p < 0.001), as well as perceived fatigue (Z = 3.9, p < 0.001) after the Stroop task. Performance analysis revealed a significant main effect of condition on vertical jump height (F = 2.9, p = 0.04) and V-CUT dribbling performance (F = 4.4, p = 0.007), but not on medicine ball throw, change of direction test, or stationary two-point shooting (p > 0.05). Mental fatigue (mental fatigue with placebo gum) significantly impaired vertical jump height (p = 0.008) and V-CUT dribbling performance (p = 0.049) compared to the no mental fatigue with placebo gum condition. No significant differences were found between other condition pairs for these performance measures.

Conclusion: Mental fatigue negatively affects power and skill performance in basketball players, while caffeine gum consumption may offer a potential strategy to mitigate these effects. While caffeine gum attenuated some performance declines in the mental fatigue with caffeine gum condition compared to mental fatigue with placebo gum, these differences were not statistically significant. Future research should explore optimal caffeine doses and additional performance variables.

Background: This study aimed to compare the Athlete Diet Index (ADI) and body composition between professional and nonprofessional athletes to better understand how differences in training and nutrition impact athletic performance and health.

Method: A comparative cross-sectional design was used to analyze 183 athletes (99 professional, 84 nonprofessional) from various sports disciplines in Tehran. Data were collected on body composition parameters, including fat mass (FM) and fat free mass (FM) using bioelectrical impedance analysis (BIA) and the ADI, a validated tool for assessing diet quality.

Results: The results revealed that professional athletes had significantly lower FM percentages (16.2% ± 7.1%) and higher FFM percentages (80.8% ± 6.8%) compared to their nonprofessional counterparts (FM 18.8% ± 9.9%, FFM 78.0% ± 9.6%). Additionally, professional athletes exhibited higher ADI scores, indicating better adherence to sports nutrition guidelines.

Conclusions: These findings highlight the benefits of structured training and personalized nutrition in achieving favorable body composition. This study underscores the importance of personalized nutrition strategies for optimizing athletic health and performance, particularly for nonprofessional athletes who may not have access to professional dietary guidance. Further research is needed to explore the long-term effects of dietary and training interventions on body composition and athletic performance across various athlete populations.

Purpose: Limited data exists that compare pre-sleep versus post-exercise protein intake during resistance exercise training (RET) in older adults. This study examined whether 40 g of protein consumed post-exercise (PRP) or pre-sleep (PSP) enhances muscle thickness (MT) and strength compared to RET alone (RETO) in older men.

Methods: Thirty untrained older men (65.7 ± 4.0 yrs) completed 12 weeks of supervised RET (2×/week) and were randomized to PRP (n = 9), PSP (n = 11), or RETO (n = 10). MT of the vastus lateralis (VL), rectus femoris (RF), and vastus intermedius (VI) and 1-repetition maximum (1-RM) for leg and chest press were assessed at weeks 0, 6, and 12.

Results: VL (0 to 12 weeks: + 0.16 cm, 95% C.I. [0.06, 0.25]), RF (0 to 12 weeks: + 0.13 cm, 95% C.I. [0.03, 0.23]), and VI MT (0 to 12 weeks: + 0.18 cm, 95% C.I. [0.05, 0.31]) and chest press (0 to 12 weeks: + 10.9 kg, 95% C.I. [5.50, 16.3]) and leg press (0 to 12 weeks: + 28.3 kg, 95% C.I. [19.63, 37.1]) 1-RM increased (p < 0.050) with no group differences.

Conclusion: Consuming 40 g of protein post-exercise or pre-sleep did not enhance RET-induced improvements in muscle thickness or strength in older adults with adequate baseline protein intake (≥1.0 g/kg/day). RET alone elicited significant gains, emphasizing that adherence to training and meeting daily protein requirements are more critical than timing strategies for untrained older adults. ClinicalTrials.gov identifier: NCT05922475, 06/23/2023, retrospectively registered.