J Int Soc Sports Nutr [JOURNAL]
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200 papers
Creatine in women's health: bridging the gap from menstruation through pregnancy to menopause.
Smith-Ryan AE, DelBiondo GM, Brown AF … +3 more , Kleiner SM, Tran NT, Ellery SJ
J Int Soc Sports Nutr · 2025 Dec · PMID 40371844 · Full text
BACKGROUND: Creatine supplementation in women has gained attention for its potential benefits beyond muscle growth, including reproductive health, cognitive health and aging. Women exhibit distinct physiological differen...
BACKGROUND: Creatine supplementation in women has gained attention for its potential benefits beyond muscle growth, including reproductive health, cognitive health and aging. Women exhibit distinct physiological differences from men, influenced by hormonal fluctuations during pre-menopause, pregnancy, and menopause, and these factors should be considered for their influence on creatine metabolism. OBJECTIVE: This review aims to provide a historical evaluation of creatine supplementation in women, its potential applications across female-specific life stages, recent research highlights, and targets for future research. The review also considers the impact of hormonal changes on creatine metabolism and effectiveness as a dietary supplementation. METHODS: This is a narrative overview of historical and recent research evaluating the effects of creatine in women. RESULTS: Early studies demonstrated the benefits of creatine on exercise performance in women, though they often overlooked menstrual cycle variability. Recent research has begun to account for these hormonal fluctuations, enhancing the understanding of creatine's applications. Creatine supplementation has shown positive effects on muscle strength, exercise performance, and body composition, particularly when combined with resistance training. Additionally, creatine may improve mood and cognitive function, potentially alleviating symptoms of depression. Emerging evidence suggests creatine's benefits during pregnancy and post-menopause, though data on perimenopausal women remains limited. CONCLUSION: Creatine supplementation presents a promising strategy for enhancing various aspects of women's health across the lifespan. Future research should focus on optimizing dosing strategies, understanding long-term health implications, and exploring creatine's effects during pregnancy and perimenopause.
Pre-sleep casein ingestion with probiotic strains improves anaerobic power and lower-body-specific strength and power performance in soccer players.
Sadeghi R, Hemmatinafar M, Eftekhari F … +2 more , Imanian B, Koureshfard N
J Int Soc Sports Nutr · 2025 Dec · PMID 40353739 · Full text
BACKGROUND: Probiotics comprise various strains that offer numerous health benefits. Researchers have recently focused on the relationship between probiotic consumption and improved gut microbiota function, enhanced dige...
BACKGROUND: Probiotics comprise various strains that offer numerous health benefits. Researchers have recently focused on the relationship between probiotic consumption and improved gut microbiota function, enhanced digestion, increased nutrient absorption, and enhanced sports performance. Therefore, the present study investigated the effects of pre-sleep casein intake, coupled with probiotic strains, on soccer players' anaerobic power, lower-body-specific strength, and power performance. METHODS: A randomized, double-blinded, and placebo-controlled study was conducted with forty-four male soccer players (Age: 22.81 ± 2.76 years, Height: 177.90 ± 6.75 cm, Weight: 67.42 ± 8.44 kg). The participants underwent the isokinetic strength, Wall-squat, and running-based anaerobic sprint (RAST) tests initially; then, they were randomly divided into four groups: probiotics (PRO), casein (CAS), probiotics with casein (PRO+CAS), and placebo (PLA). The PRO groups were given one probiotic capsule (containing eight bacterial strains: BP06, BP07, BA05, BD08, Bifidobacterium infantis BI04, BL03, BB02, and BT01, with a total dose of 4.5 × 10 CFU) during dinner, while the CAS groups consumed 20 grams of casein powder 45 minutes before bed. The PRO+CAS group was given one probiotic capsule during dinner and 20 grams of casein powder 45 minutes before bed. The participants in the PLA group were given one red capsule (containing 5 grams of starch) during dinner. All participants were instructed to take the supplements only on training days, three times a week for four weeks. Additionally, isokinetic strength parameters, including absolute peak torque (APT) and average rate of force development (AvRFD), were measured for the knee extensors (ext) and flexors (flx) muscles (concentric phase at angular velocities of 60°/s and 180°/s, using the dominant leg). One-way analysis of covariance (ANCOVA) or Quade tests with a significance level of < 0.05 was used to analyze the collected data. RESULT: The current study's findings indicated that APT-180°/s (ext) significantly increased in CAS ( = 0.008) and PRO+CAS ( = 0.003) compared to PLA. Additionally, the AvRFD-180°/s (ext) increased significantly in the PRO compared to the PLA ( = 0.007). Also, the AvRFD-60°/s (flx) increased significantly in the PRO+CAS group compared to the PLA ( = 0.014), CAS ( = 0.001), and PRO ( = 0.007). Furthermore, the AvRFD-180°/s (flx) increased significantly in the PRO+CAS compared to the CAS ( = 0.010). Moreover, the RAST average power increased dramatically in PRO+CAS compared to PLA ( = 0.003) and CAS ( = 0.02). Additionally, the Wall-squat test demonstrated a significant increase in PRO+CAS compared to PLA ( = 0.001) and PRO ( = 0.001). However, there were no significant differences in the APT-60°/s (ext&flx), APT-180°/s (flx), and AvRFD-60°/s (ext) between groups ( > 0.05). CONCLUSION: The simultaneous consumption of casein and probiotics significantly improved anaerobic power, isokinetic strength, and lower-body muscular endurance in male soccer players. These enhancements were more pronounced than those observed with casein or probiotics alone, as supported by statistical significance and effect sizes. The findings suggest a synergistic benefit of combined supplementation for athletic performance.
The effect of acute beetroot juice consumption prior to climbing on lower-body isokinetic and isometric strength, aerobic power, and muscle soreness among mountain climbers.
Daneshparvar A, Hemmatinafar M, Salesi M … +3 more , Rezaei R, Imanian B, Pirmohammadi S
J Int Soc Sports Nutr · 2025 Dec · PMID 40323707 · Full text
BACKGROUND: Beetroot juice (BRJ) contains various bioactive compounds which can enhance athletes" performance. However, there is a limited number of studies assessing the effects of BRJ on climbers" performance and indic...
BACKGROUND: Beetroot juice (BRJ) contains various bioactive compounds which can enhance athletes" performance. However, there is a limited number of studies assessing the effects of BRJ on climbers" performance and indicators of muscle soreness (MS). Thus, the present study aimed to investigate the effect of consuming beetroot juice acutely before climbing on lower-body isokinetic and isometric strength, aerobic power, and muscle soreness in mountain climbers. METHODS: In a randomized, placebo-controlled, double-blinded study, 27 climbers (14 males and 13 females) were divided into three groups: Control (CON), Placebo (PLA), and Beetroot Juice (BRJ), with 9 participants in each group. The study evaluated swelling around the thigh (Sw-T), pressure pain threshold (PPT), isokinetic and isometric strength, horizontal jump (HJ), wall-sit, handgrip strength (HGS), flexibility, and the Queen's College Step test. Testing occurred in three sessions: baseline, climbing, and posttest. At baseline, all participants completed the full battery of tests at Shiraz University. One week later, during the climbing session, they consumed 70 mL of BRJ (400 mg nitrate), PLA, or water 2.5 hours before ascending to 3720 meters. Functional tests (HJ, wall-sit, and estimated VO₂) were performed at the altitude. After completing these tests, participants immediately descended the mountain. DOMS was assessed using a visual analog scale (VAS) for the quadriceps, hamstrings, and gastrocnemius muscles at the following time points: 2 hours before climbing, and 0 (immediately), 12, 24, 48, and 72 hours after descending. The posttest session, held 72 hours after descending, repeated all baseline assessments. RESULTS: The results revealed a statistically significant decrease in DOMS in the gastrocnemius muscles 24 hours post-descending in the BRJ group compared to the control group ( = 0.003, pEta = 0.204). However, no changes in DOMS were observed for the quadriceps ( = 0.090, pEta = 0.090) and hamstring ( = 0.254, pEta = 0.056) muscles. Moreover, notable improvements were observed in PPT ( = 0.001, pEta = 0.374), Estimated VO ( = 0.016, pEta = 0.291), HGS ( = 0.004, pEta = 0.270), flexibility ( = 0.003, pEta = 0.407), HJ ( = 0.008, pEta2 = 0.155), and isokinetic (peak torque, average power and rate of force development) and isometric (Maximum voluntary isometric contraction) strength indicators in the BRJ groups compare to the other groups (p˂0.05). However, no significant differences were observed in Sw-T between groups ( = 0.305). CONCLUSIONS: The study suggested that acute consumption of BRJ before climbing improves climbers' lower-body isokinetic and isometric strength, power, and endurance performance, and it is associated with a reduced perception of muscle soreness.
Caffeine's influence on vertical jump height: a real-life collegiate student-athlete approach.
Papadakis Z, Panoutsakopoulos V, Schwarz A … +1 more , Antonio J
J Int Soc Sports Nutr · 2025 Dec · PMID 40320739 · Full text
BACKGROUND: Caffeine's ergogenic potential in vertical jumping remains contested, particularly at dosages compliant with collegiate athletic regulations. The NCAA enforces a caffeine urinary threshold equivalent to ~5 mg...
BACKGROUND: Caffeine's ergogenic potential in vertical jumping remains contested, particularly at dosages compliant with collegiate athletic regulations. The NCAA enforces a caffeine urinary threshold equivalent to ~5 mg/kg body mass, yet evidence supporting its efficacy in enhancing explosive performance among trained athletes is inconsistent. This study examined whether acute caffeine ingestion at this threshold improves squat jump (SJ) and countermovement jump (CMJ) performance in NCAA Division II student-athletes, while exploring sex-specific responses and trial-to-trial variability. METHODS: Forty NCAA Division II athletes (18 females, 22 males; 21.3 ± 2.4 years) participated in a single-blind, randomized, crossover trial. Participants ingested 5 mg/kg caffeine or placebo, followed by SJ and CMJ testing on a force platform 60 minutes post-consumption. Three trials per jump type were retained to preserve intra-individual variance. Linear mixed-effects models (LMMs) assessed fixed effects of condition, sex, and trials, with random intercepts and slopes accounting for individual variability. A priori power analyses guided sample size determination, targeting sensitivity to detect small-to-medium effects (Cohen's f ≥ 0.2). RESULTS: Caffeine elicited trivial, non-significant differences in SJ (β = -0.24 cm, = 0.646) and CMJ (β = -0.71 cm, = 0.183) heights compared to placebo. Males outperformed females in both SJ (Δ = 9.50 cm, < 0.001) and CMJ (Δ = 11.30 cm, < 0.001), though no condition-by-sex interactions emerged. Trial effects were observed, with SJ improving 2.31 cm ( < 0.001) and CMJ 1.05 cm ( = 0.014) from first to second attempts, suggesting warm-up or neuromuscular potentiation. High intraclass correlation coefficients (ICC = 0.76-0.85) underscored substantial interindividual variability. Models demonstrated robust fit (conditional R = 0.86-0.92), with sufficient power to detect medium-to-large effects (f ≥ 0.25). CONCLUSIONS: A 5 mg/kg caffeine dose, compliant with NCAA thresholds, did not enhance vertical jump performance in habituated collegiate athletes, challenging prior assertions of its universal ergogenicity for ballistic tasks. While sex differences in baseline performance persisted, caffeine did not modulate these disparities, implicating neuromuscular and anthropometric factors as primary determinants. The absence of ergogenic effects aligns with NCAA safety-focused policies but highlights the need for personalized dosing strategies and research into higher doses, genetic variability, and hormonal influences. Future studies should integrate biomechanical metrics and controlled hormonal assessments to elucidate caffeine's nuanced role in anaerobic power sports.
Toward promoting performance nutrition behaviors among tactical athletes: a mixed methods study.
Baker B, Carins J, Peterson R … +2 more , Belski R, Cooke MB
J Int Soc Sports Nutr · 2025 Dec · PMID 40314558 · Full text
BACKGROUND: Appropriate and adequate nutrition is essential for the health and performance of tactical athletes, including army recruits and trainees. However, previous research shows they commonly experience suboptimal...
BACKGROUND: Appropriate and adequate nutrition is essential for the health and performance of tactical athletes, including army recruits and trainees. However, previous research shows they commonly experience suboptimal intakes of energy and carbohydrate. To date, little research has been conducted to understand the causes of their poor dietary intakes. The objectives of this study were to (1) assess infantry trainees' dietary intakes and (2) explore their beliefs, barriers, and self-efficacy toward performance nutrition using the Health Belief Model (HBM). METHODS: Participants undergoing their 17-week Australian Army Infantry Initial Employment Training (Infantry IET) were recruited. During weeks 1 and 17, self-reported dietary intakes were assessed, and four focus groups were conducted. RESULTS: Mean daily energy, carbohydrate, and protein intakes were 7864 ± 1135 kJ, 1.8 ± 0.6 g/kg, and 1.5 ± 0.3 g/kg, respectively, in week 1, and 9084 ± 2535 kJ/day, 2.2 ± 1.1 g/kg and 1.5 ± 0.2 g/kg, respectively, in week 17. Three themes and seven subthemes were developed from the focus group data, falling under the following HBM domains: Cues to Action, Perceived Barriers, and Self-Efficacy. CONCLUSIONS: Infantry trainees' ability to eat well for their health and performance was hindered by their limited time during their intensive training schedule, their limited access to a sufficient variety of healthy foods, and their limited self-efficacy regarding performance nutrition. They require further performance nutrition knowledge, especially in regard to adopting practical fueling and refueling strategies surrounding physical training, as well as access to a greater quantity and variety of healthy foods outside of their main mealtimes.
Physiological effects of spirulina supplementation during lactate threshold exercise at simulated altitude (2,500 m): a randomized controlled trial.
Gurney T, Brouner J, Spendiff O
J Int Soc Sports Nutr · 2025 Dec · PMID 40310870 · Full text
BACKGROUND: Existing literature indicates that spirulina supplementation can improve a variety of blood morphological parameters (such as hemoglobin) in healthy and clinical populations. Given the importance of hemoglobi...
BACKGROUND: Existing literature indicates that spirulina supplementation can improve a variety of blood morphological parameters (such as hemoglobin) in healthy and clinical populations. Given the importance of hemoglobin for endurance exercise, particularly at altitude, this study aimed to investigate whether spirulina supplementation can improve blood morphological parameters in healthy cyclists and positively influence physiological variables when completing a lactate threshold test at simulated moderate altitude (2,500 m). METHODS: Twenty (18 male; 2 female) healthy participants (Mean ± SD; Age 37 ± 9 years, Stature 181 ± 6 cm, Mass 81 ± 9 kg, O 51.8 ± 7.8 ml·kg-1·min-1) ingested 6 g/day of spirulina or placebo for 3-weeks in a double-blinded randomized counter-balanced cross-over design, then completed a lactate threshold test at simulated moderate altitude, with a 14-day washout period between trials. RESULTS: Following spirulina supplementation, heart rate at the lactate threshold was significantly lower in comparison to placebo supplementation (spirulina = 152 ± 11 b.min -1 vs. placebo = 155 ± 12 b.min -1, < 0.05). No other physiological variables (Watts, RER, RPE, VO) were significantly different ( > 0.05) at the calculated threshold, or during the first four lower stages. Red Cell Distribution Width significantly increased following spirulina supplementation in comparison to placebo (spirulina = 13.3 ± 0.9 % vs. placebo = 12.5 ± 0.7 %, < 0.05). Plateletcrit significantly decreased following spirulina supplementation (spirulina = 0.288 ± 0.032 vs. placebo = 0.293 ± 0.050, < 0.05). No other blood morphological parameters changed ( > 0.05). CONCLUSION: In conclusion, three weeks of spirulina supplementation at 6 g/day reduced heart rate during a lactate threshold test at a simulated moderate altitude (2,500 m), but did not produce additional physiological or hematological benefits.
Impact of sports nutrition education on awareness and knowledge among physical education majors and workers.
Lee KL, Sung JY
J Int Soc Sports Nutr · 2025 Dec · PMID 40296545 · Full text
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 uni...
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 < 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 ( < 0.001) on a 5-point Likert scale, with participants who had completed nutrition classes scoring higher ( < 0.001).The GNKQ also found that participants who received nutrition classes scored higher in all sections, including the total scores (total score, = 0.011; one section, = 0.030; three sections, < 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.
Does creatine cause hair loss? A 12-week randomized controlled trial.
Lak M, Forbes SC, Ashtary-Larky D … +9 more , Dadkhahfar S, Robati RM, Nezakati F, Khajevandi M, Naseri S, Gerafiani A, Haghighat N, Antonio J, Tinsley GM
J Int Soc Sports Nutr · 2025 Sep · PMID 40265319 · Full text
BACKGROUND: Creatine is a widely used ergogenic aid that enhances muscle strength and lean mass. However, concerns have been raised about the potential role in promoting hair loss by increasing dihydrotestosterone (DHT)....
BACKGROUND: Creatine is a widely used ergogenic aid that enhances muscle strength and lean mass. However, concerns have been raised about the potential role in promoting hair loss by increasing dihydrotestosterone (DHT). Currently, there is no direct evidence examining the relationship between creatine supplementation and hair follicle health. Therefore, the purpose was to determine the effects of 12 weeks of creatine supplementation on androgen levels and hair follicle health in healthy young males. METHODS: Forty-five resistance-trained males (ages 18-40 years) were recruited and randomly assigned to either a creatine monohydrate (5 g/day) or placebo (5 g maltodextrin/day) group. Participants maintained their habitual diets and training routines. Blood samples were collected at baseline and after 12 weeks to measure total testosterone, free testosterone, and DHT. Hair follicle health was assessed using the Trichogram test and the FotoFinder system (hair density, follicular unit count, and cumulative hair thickness). Statistical analyses were performed using repeated measures ANOVA, and potential outliers were examined through sensitivity analysis. RESULTS: Thirty-eight participants completed the study, with no significant differences in baseline characteristics between groups. There were no group-by-time interactions observed for any hormones or hair-related outcomes ( > 0.05). While total testosterone increased (∆ = post value minus pre value: creatine = ∆124 ± 149 ng/dL; placebo = ∆216 ± 203 ng/dL) and free testosterone decreased (creatine = ∆-9.0 ± 8.7 pg/mL; placebo = ∆-9 ± 6.4 pg/mL) over time, these effects were independent of supplementation. There were no significant differences in DHT levels, DHT-to-testosterone ratio, or hair growth parameters between the creatine and placebo groups. CONCLUSION: This study was the first to directly assess hair follicle health following creatine supplementation, providing strong evidence against the claim that creatine contributes to hair loss.
Dietary supplement use and knowledge among athletes: prevalence, compliance with AIS classification, and awareness of certification programs.
Broniecka A, Sarachman A, Zagrodna A … +1 more , Książek A
J Int Soc Sports Nutr · 2025 Dec · PMID 40263114 · Full text
BACKGROUND: The use of dietary supplements is widespread among athletes, with intake influenced by factors such as sport-discipline, competitive level, and gender. The Australian Institute of Sport (AIS) has categorized...
BACKGROUND: The use of dietary supplements is widespread among athletes, with intake influenced by factors such as sport-discipline, competitive level, and gender. The Australian Institute of Sport (AIS) has categorized supplements based on scientific evidence regarding their efficacy and safety. Despite extensive global research on dietary supplement use among athletes, data on Polish athletes remain limited. Therefore, this study aimed to evaluate supplement use among Polish athletes, considering their competitive level and gender. Additionally, it assessed whether athletes select supplements in accordance with the AIS classification and examined their awareness of supplement certification programs. METHODS: This cross-sectional study included 659 Polish athletes (309 women, 350 men) from various sports, representing both professional (57.7%) and nonprofessional (42.3%) levels. An online questionnaire was used to assess dietary supplement consumption, sources of information regarding supplementation, and knowledge of anti-doping and supplement certification programs. Supplement use was categorized according to the AIS classification (Groups A - D). Statistical analyses, including chi-square tests and Mann - Whitney U tests, were conducted to evaluate differences between professional and nonprofessional athletes, as well as between male and female participants. RESULTS: A high prevalence of dietary supplement use (91.1%) was observed among Polish athletes, with no significant differences between professional (95.8%) and nonprofessional (94.3%) athletes or between men (92.0%) and women (90.0%). The most frequently consumed supplements were sports drinks (63.9%), electrolyte supplements (51.6%), and isolated protein supplements (54.6%), vitamin D (71.6%), vitamin C (59.8%), with significantly higher intake among professional athletes. Male athletes were more likely than females to consume caffeine ( < 0.001), creatine ( < 0.001), and β-alanine ( < 0.001). Melatonin use was significantly higher among professionals ( < 0.05). Awareness of WADA regulations was moderate (72.7%), but knowledge of supplement certification programs was low, with only 18.2% of professional athletes familiar with Informed Sport, and 10.7% with the Cologne List. Social media was the most common source of supplement information (41.9%), while only 17.6% of athletes consulted qualified specialists in sports nutrition and supplementation area. CONCLUSIONS: This study highlights the widespread use of dietary supplements among Polish athletes, irrespective of competitive level or gender. While many athletes select supplements from AIS Group A, their knowledge of AIS classification and supplement certification programs remains limited. The high reliance on social media for supplement information, combined with the lack of professional guidance, underscores the need for improved education on safe and effective supplementation practices. Given the risks associated with supplement contamination, targeted initiatives should enhance athletes' awareness of anti-doping regulations and certified supplement options.
Assessing the risk of low energy availability, bone mineral density and psychological strain in endurance athletes.
Gowers CR, McManus CJ, Chung HC … +3 more , Jones B, Tallent J, Waterworth SP
J Int Soc Sports Nutr · 2025 Dec · PMID 40262556 · Full text
BACKGROUND: Adequate energy intake is crucial for athletic performance and recovery. However, many endurance athletes experience Low Energy Availability (LEA), which, if prolonged, can detrimentally impact both health an...
BACKGROUND: Adequate energy intake is crucial for athletic performance and recovery. However, many endurance athletes experience Low Energy Availability (LEA), which, if prolonged, can detrimentally impact both health and performance. METHODS: A total of 55 endurance athletes (23 females; 45 ± 13 years, 1.64 ± 0.06 m, 64.4 ± 11.4 kg and 32 males; 44 ± 13 years, 1.76 ± 0.18 m, 78.8 ± 9.2 kg) underwent physical assessments and completed questionnaires on dietary habits, training loads, and psychological stress. Dual-Energy X-ray Absorptiometry (DEXA) scans measured bone mineral density (BMD) in the lumbar L1-L4 spine, and body composition. Risk of LEA burnout, and psychological strain were assessed using sport-specific questionnaires. RESULTS: Seventy-seven percent of female athletes were identified as at risk of LEA by the LEAF-Q. These females had higher body weight and fat percentage than those at low risk of LEA. Male athletes had a higher prevalence of low lumbar BMD (31%) compared to females, associated with older age, and longer training histories. Although only 9% of female athletes had low-BMD, those affected had a history of amenorrhea and were identified as at risk of LEA by the LEAF-Q. CONCLUSION: A high proportion of endurance athletes had low-BMD and were at risk of LEA. This underscores the need for targeted nutritional strategies to mitigate the risks associated with LEA and promote overall athlete well-being.
Impact of carbohydrate timing on glucose metabolism and substrate oxidation following high-intensity evening aerobic exercise in athletes: a randomized controlled study.
Mattsson S, Edin F, Trinh J … +3 more , Adolfsson P, Jendle J, Pettersson S
J Int Soc Sports Nutr · 2025 Dec · PMID 40259503 · Full text
OBJECTIVE: The study aimed to investigate the impact of nutrient timing in relation to evening exercise. Specifically, it examined the effects of pre- or post-exercise carbohydrate (CHO) ingestion on glucose metabolism,...
OBJECTIVE: The study aimed to investigate the impact of nutrient timing in relation to evening exercise. Specifically, it examined the effects of pre- or post-exercise carbohydrate (CHO) ingestion on glucose metabolism, glucose regulation, and overall substrate oxidation in well-trained athletes during and after physical exercise (PE), spanning the nocturnal period and the subsequent morning. METHODS: Ten male endurance cyclists participated in the study. The initial assessments included body composition measurements and an incremental cycle test to determine maximal oxygen uptake (O2 max) and maximum power output (Wmax). Following this, participants underwent a control (rest previous day) oral glucose tolerance test (OGTT) and a familiarization exercise trial that had two objectives: (1) to establish the appropriate amount of CHO to use in the pre- or post-exercise drink during the experimental trials, and (2) to familiarize participants with the equipment and study protocol. In the three days prior to both the control and experimental trials, participants followed a standardized, individualized diet designed to meet their energy needs. During the experimental trials, participants completed two separate evening exercise sessions (50 min@70%Wmax + ~24 min time-trial (TT)) with either pre- or post-exercise CHO ingestion (253 ± 52 g), matching the CHO oxidized during exercise. The CHO drink and a volume-matched placebo (PLA) drink (containing no energy) were randomly assigned to be consumed two hours before and directly after the experimental exercise sessions. Post-exercise nocturnal interstitial glucose levels (24:00-06:00) were continuously monitored, and a 120-min OGTT was conducted the following morning to assess substrate oxidation rates and glucose control. RESULTS: Pre-exercise CHO intake significantly lowered capillary glucose levels during steady-state exercise (mean difference 0.41 ± 0.27 mmol/L, = 0.001) without affecting perceived exertion and TT-performance. No difference was observed in nocturnal glucose regulation (00:00-06:00) regardless of whether CHO was consumed before or after exercise. Post-exercise CHO ingestion reduced glucose tolerance during the OGTT compared to the iso-caloric pre-exercise CHO intake (mean difference 0.76 ± 0.21 mmol/L, = 0.017). However, a post-exercise CHO intake improved respiratory exchange ratio/metabolic flexibility (MetF) significantly. Enhanced MetF during the first OGTT hour after post-exercise CHO ingestion resulted in 70% and 91% higher CHO oxidation compared to pre-exercise CHO and control, respectively ( ≤ 0.029). Average 120-min OGTT fat oxidation rates were higher with both pre- and post-exercise CHO ingestion compared to control ( ≤ 0.008), with no difference between pre- and post-exercise CHO intake. CONCLUSION: Morning glucose tolerance was markedly reduced in healthy athletes when CHO was ingested after evening exercise. However, the observed improvements in MetF during the OGTT compared to placebo post-exercise suggest a potential for enhanced athletic performance in subsequent exercise sessions. This opens exciting possibilities for future research to explore whether enhanced MetF induced by CHO-timing can translate to improved athletic performance, offering new avenues for optimizing training and performance.
Caregivers nutrition knowledge and perspectives on the enablers and barriers to nutrition provision for male academy football players.
Cole M, Carter JL, Brooks F … +1 more , Roberts CJ
J Int Soc Sports Nutr · 2025 Dec · PMID 40259501 · Full text
BACKGROUND: The assessment of nutrition knowledge, alongside the enablers and barriers to optimal dietary intake, in youth football players has previously been documented. However, there is comparatively little research...
BACKGROUND: The assessment of nutrition knowledge, alongside the enablers and barriers to optimal dietary intake, in youth football players has previously been documented. However, there is comparatively little research on either of these within parents or host families, which is of value to understand given the vital role that these stakeholders play as the primary food provider to young football players. Thus, the purpose of this study was to assess the nutrition knowledge of these caregivers and explore their perceptions of the barriers and enablers to nutrition provision for male academy football players. METHODS: A validated 35-item online questionnaire (A-NSKQ) was completed by 30 parents and 31 host family providers of youth academy football players from 16 different professional football clubs in England. The questionnaire consisted of 35 questions (total), 11 of which focussed on the assessment of general nutrition knowledge (GNK) and the remaining 24 assessed sports nutrition knowledge (SNK). Scores are presented as a percentage for total and each sub-section (GNK & SNK) and classified by the following rating: "poor" (0-49%); "average" (50-65%); "good" (66-75%); and "excellent" knowledge (76-100%). Differences in Total, GNK and SNK were compared between parents and host families using Independent-samples t-tests, with the alpha value set at < 0.05 for all tests. A series of focus groups was also conducted with six parents and twelve host family representatives from four clubs to explore their perspectives of the enablers and barriers to providing nutrition support to youth football players. Thematic analysis was used to interpret the data. RESULTS: Host family providers demonstrated significantly better total nutrition knowledge than Parents (49.95 ± 11.64% vs. = 42.67 ± 14.43%; = 0.035), although the knowledge of both groups is classed as "poor." For the sub-sections of GNK & SNK, GNK was considered "average" and significantly better than SNK, which was classed as "poor" (GNK = 58.12 ± 16.87% vs. SNK = 40.98 ± 14.91%; < 0.001). Host family providers reported significantly better SNK than parents (44.89 ± 13.21% vs. 36.94 ± 15.69%; = 0.037) whilst no significant differences were observed in GNK between groups (61.00 ± 15.07% vs. 55.15 ± 18.33%; = 0.180). Three key themes were generated relating to the caregivers' perceptions of the barriers and enablers to their food provision: 1) Club Support and Communication; 2) Time and Financial Resources; 3) Player-specific Characteristics. CONCLUSIONS: These findings suggest a clear need for football clubs to educate caregivers in the fundamental principles of healthy nutrition and football-specific nutrition requirements and encourage clubs to develop initiatives to better support caregivers in helping to young players to meet their dietary requirements.
The impact of low energy availability risk on pre-competition physiological function in Chinese female combat athletes.
Liang Y, Li Y, Chen Y … +5 more , Meng K, Zhou F, Pei Y, Liu Y, Qiu J
J Int Soc Sports Nutr · 2025 Dec · PMID 40254934 · Full text
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...
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 ( = 38) were at increased risk of LEA, and 21.4% of athletes ( = 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 VO and resting metabolic rate at 0 week of the competition compared to 4 weeks prior ( < 0.05). Thyroid function indicators and IGF-1 levels of LEA group also significantly decreased ( < 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 ( < 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.
Elite collegiate swimmers do not meet sport nutrition recommendations during heavy training: effects of sex and within-day nutrient timing.
Lundstrom EA, De Souza MJ, Khen KM … +1 more , Williams NI
J Int Soc Sports Nutr · 2025 Dec · PMID 40249655 · Full text
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 Olym...
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 ( = 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 ( < 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; = 0.014). No swimmers met CHO recommendations (g⋅kg) 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⋅hr) for FAT (Sex; F = 5.659, = 0.26; time; F = 12.068, = 0.006) and PRO (Sex; F = 6.719, = 0.016; time; F = 13.177, = 0.011). There was a significant sex*time interaction for CHO consumption (F = 6.520, = 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.
Individual responses to encapsulated caffeine and caffeine chewing gum on strength and power in strength-trained males.
Teimouri-Korani H, Hemmatinafar M, Willems ME … +2 more , Rezaei R, Imanian B
J Int Soc Sports Nutr · 2025 Dec · PMID 40249126 · Full text
BACKGROUND: Liquid-dissolved and encapsulated powder are two popular ways to consume caffeine for performance-enhancing effects. Caffeine in other delivery methods, such as chewing gums, orally dissolvable strips, gels,...
BACKGROUND: Liquid-dissolved and encapsulated powder are two popular ways to consume caffeine for performance-enhancing effects. Caffeine in other delivery methods, such as chewing gums, orally dissolvable strips, gels, mouthwashes, energy drinks, and nasal sprays, is believed to be absorbed more quickly into the bloodstream. Inter-individual responses to caffeine's enhancing effects are recognized. The present study examined the inter-individual responses to the acute effects of encapsulated caffeine and caffeinated chewing gum on the lower-body isokinetic and isometric strength and power in strength-trained males. METHOD: A randomized, cross-over, placebo-controlled study was conducted with 15 strength-trained males (age: 25 ± 4 years, height: 176 ± 7 cm, weight: 75 ± 11 kg, habitual caffeine intake: 66 ± 15 mg·day). Participants were randomly assigned to three conditions: i) caffeinated chewing gum (CG), ii) caffeine capsule (CC), and iii) starch capsule as a placebo (PLA). Participants consumed approximately 3 to 4.5 mg·kg of caffeine 60 minutes before testing. The washout period between conditions was one week. Participants performed the Sargent jump test, followed by a 5-minute active recovery (walking). Subsequently, isokinetic strength and power (60°/s and 180°/s) and isometric strength (45° and 60°) parameters were measured for knee extensor and flexor muscles. Data were analyzed using one-way repeated measures ANOVA and Bonferroni post hoc tests, with significance set at ≤ 0.05. Responders to the caffeine conditions were identified using the smallest worthwhile change (SWC) analysis. RESULTS: In knee extensors, 1) average peak torque and power at 60°/s were higher in CC ( = 0.045; + 11.2% and = 0.038; + 14.1%) and CG ( = 0.044; + 7.3% and = 0.015; + 11.4%) compared to PLA with a co-response rate of 60% and 66%, 2) maximum voluntary isometric contraction at 45° (MVIC-45°) was higher in CC compared to PLA ( = 0.031; + 10.1%), and 3) MVIC-60° was higher in CG compared to PLA ( = 0.037; + 10.1%) with a co-response rate of 60%. In knee flexors, 1) time to peak torque at 60°/s was higher in CG compared to PLA ( = 0.011; + 18.2%) with a co-response rate of 46%, 2) average rate of force development at 60°/s was higher in CC ( = 0.007; + 24.1%) and CG ( = 0.050; + 20.6%) compared to PLA with a co-response rate of 53%, and 3) average power at 180°/s was higher in CC compared to PLA ( = 0.033; + 18%) with a co-response rate of 46%. However, there were no differences between other strength indicators in the knee extensors and flexors between the different conditions. Vertical jump height (VJH) was higher in CC ( = 0.001; + 5.5%) and CG ( = 0.001; + 6.) compared to PLA, with a co-response rate of 53%. CONCLUSION: Caffeine supplementation in CC and CG forms significantly enhanced lower-body strength, power, and vertical jump height in strength-trained males, with over ~50% of participants exceeding the SWC thresholds across key performance metrics. CC showed slightly higher responder rates for strength parameters, while CG excelled in time-dependent measures, supporting their use as effective and flexible ergogenic aids.
Hypercaloric 16:8 time-restricted eating during 8 weeks of resistance exercise in well-trained men and women.
Blake DT, Hamane C, Pacheco C … +6 more , Henselmans M, Tinsley GM, Costa P, Coburn JW, Campidell T, Galpin AJ
J Int Soc Sports Nutr · 2025 Dec · PMID 40241374 · Full text
BACKGROUND: The effectiveness and practicality of time-restricted eating (TRE) when trying to maximize muscle mass and strength is unclear. Thus, we examined the effects of a hypercaloric 16:8 TRE approach during supervi...
BACKGROUND: The effectiveness and practicality of time-restricted eating (TRE) when trying to maximize muscle mass and strength is unclear. Thus, we examined the effects of a hypercaloric 16:8 TRE approach during supervised progressive resistance exercise. METHODS: Seventeen healthy and well-trained men ( = 10) and women ( = 7) were randomly assigned to TRE or control (FED). Both groups consumed a 10% hypercaloric high-protein (2.2 g/kg/d) diet and performed supervised resistance exercise 4× per wk for 8 wk. TRE consumed all calories within an 8 h window starting at least 1 h post-exercise, while FED consumed the same number of calories throughout the day. RESULTS: Eating windows were significantly different (TRE: 7.9 ± 0.1 h vs. FED: 13.2 ± 0.6 h). Calorie, carbohydrate, fat, and protein intake did not differ statistically between groups. Total exercise volume was significantly lower in TRE than FED (6,960 ± 287 vs. 7,334 ± 289 repetitions), as were subjective daily energy ratings (week 4 = -1.41; = 0.04, week 8 = -1.04; = 0.06). Both groups increased maximal upper and lower body strength (1RM) and muscular endurance (ME); however, gains in squat 1RM were 4.0 ± 1.9 kg lower in TRE ( = 0.05). Both groups increased fat-free mass similarly (TRE: 2.67 kg; FED: 1.82 kg, = 0.04), but FED added 1.4 ± 0.6 kg more fat mass ( = 0.04). Subjective mood and sleep ratings did not change in either group. CONCLUSIONS: 16:8 TRE is viable during periods of muscle size, strength, and endurance development in well-trained young men and women when engaging in progressive resistance exercise and eating in a caloric surplus with adequate protein. However, the differences in total training volume, squat 1RM, fat mass accumulation, and energy are notable and practically relevant. These findings should be considered within the broader context of an individual's goals, lifestyle, preferences, and exercise demands.
Sport supplementation in competitive swimmers: a systematic review with meta-analysis.
Domínguez R, López-León I, Moreno-Lara J … +4 more , Rico E, Sánchez-Oliver AJ, Sánchez-Gómez Á, Pecci J
J Int Soc Sports Nutr · 2025 Dec · PMID 40205676 · Full text
BACKGROUND: Competitive swimmers have a high prevalence of sports supplement (SS) consumption. However, only a few SS are scientifically proven to be safe, effective, and legal. Therefore, before incorporating supplement...
BACKGROUND: Competitive swimmers have a high prevalence of sports supplement (SS) consumption. However, only a few SS are scientifically proven to be safe, effective, and legal. Therefore, before incorporating supplements to enhance performance and health in competitive swimming, it is crucial to conduct an analysis and review to assess their effects. The objective of this study was to analyze the demonstrated effects of SS, as reported in published studies, on the swimming performance of competitive swimmers. METHODS: Following PRISMA guidelines, a systematic search was conducted across six databases for the selection of studies included in this review. Studies that analyzed the effects of sports supplementation compared to placebo were included and subjected to meta-analysis. RESULTS: This revision included 23 studies, 16 of them (69.6%) qualified as excellent and 7 (30.4%) as good at the methodological level based on the punctuation in the PEDro scale. The systematic review included 422 swimmers (61.8% male, 38.2% female), with distances assessed ranging from 50 m to 800 m, including studies employing interval procedures. Creatine showed a significant effect (ES = -0.46; 95% CIs = -0.75 to -0.17, = 0.002; I = 11%) on swimming performance, while the rest of the analyzed supplements did not show significant effects (all > 0.05). CONCLUSIONS: Creatine supplementation demonstrated ergogenic benefits for competitive swimmers, although the evidence supporting the use of this supplement is still limited. Sodium bicarbonate and β-alanine may enhance performance in distances with higher glycolytic demands, while caffeine is effective at dosages of 3-6 mg/kg administered 60 min before exercise. Further research is needed to confirm the potential ergogenic effects of other supplements, such as beetroot juice.
Safety of creatine supplementation: analysis of the prevalence of reported side effects in clinical trials and adverse event reports.
Kreider RB, Gonzalez DE, Hines K … +2 more , Gil A, Bonilla DA
J Int Soc Sports Nutr · 2025 Sep · PMID 40198156 · Full text
BACKGROUND: Individual studies have indicated that creatine supplementation is generally well tolerated and not associated with clinically significant side effects. Nevertheless, anecdotal reports about side effects pers...
BACKGROUND: Individual studies have indicated that creatine supplementation is generally well tolerated and not associated with clinically significant side effects. Nevertheless, anecdotal reports about side effects persist primarily from popular and social media and on the Internet. METHODS: This study evaluated side effects reported from 685 human clinical trials on creatine supplementation, worldwide adverse event report (AER) databases, and performed a social media sentiment analysis. The presence of side effects (No, Yes) in studies was evaluated using chi-squared analysis. The frequency of side effects among study participants was evaluated using a multivariate analysis of variance. RESULTS: A total of 13,452 participants in 652 studies ingested placebos (PLA), while 12,839 participants in 685 studies consumed creatine (Cr). Nearly all studies (95%) provided CrM at an average dose of 0.166 [0.159, 0.173] g/kg/d (about 12.5 g/d) for 64.7 [52.0, 77.3] days in studies lasting up to 14 yrs. Side effects were reported in 13.2% of studies in the PLA groups and 13.7% of studies in the Cr-supplemented groups, with no significant differences observed between the groups ( = 0.776). There was a slightly higher percentage of studies reporting gastrointestinal (GI) issues (PLA 4.3%, Cr 4.9%, < 0.001) and muscle cramping/pain (PLA 0.9%, Cr 2.9%, = 0.008) with Cr supplementation, but not when the total number of participants in these studies was evaluated (muscle cramping/pain: PLA 0.07%, Cr 0.52%, = 0.085; GI issues: PLA 4.05%, Cr 5.51%, = 0.820). Additionally, there was no significant multivariate difference among the 49 side effects evaluated ( = 0.340), no significant difference in the total frequency of side effects reported among participants (PLA 4.21%, Cr 4.60%, = 0.828), and no significant differences in any of the other side effect evaluated that included markers of renal function and health. The percentage prevalence of side effects was small, with differences between groups generally within ± 0.5%. Analysis of 28.4 million AERs revealed that the mention of Cr was rare (0.00072%), 46.3% of CAERS had no Cr in the products listed, and 63% of AERs with Cr in the product involved the use of other types of Cr or ingestion with other supplements or drugs. The overall sentiment analysis was neutral about perceptions of Cr, although those with strong perceptions about Cr were slightly more negative. CONCLUSION: Results demonstrate that Cr supplementation does not increase the prevalence or frequency of side effects when compared to participants ingesting PLA. Therefore, claims that Cr supplementation increases the risk of side effects are unfounded.
Efficacy of time restricted eating and resistance training on body composition and mood profiles among young adults with overweight/obesity: a randomized controlled trial.
Cui T, Sun Y, Ye W … +2 more , Liu Y, Korivi M
J Int Soc Sports Nutr · 2025 Dec · PMID 40108888 · Full text
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...
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 ( < 0.01) decreased body weight (>2 kg) and BMI (~1 kg/m) 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 ( < 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 ( < 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, < 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; < 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.
Macronutrient requirements and intake by professional male rugby players.
Meyer M, du Toit E, Nel R … +1 more , Coetzee D
J Int Soc Sports Nutr · 2025 Dec · PMID 40099872 · Full text
BACKGROUND: Rugby union is a high-contact team sport where professional rugby players are exposed to considerable training and game loads in pre-season and in-season. Some studies have shown that rugby players' dietary i...
BACKGROUND: Rugby union is a high-contact team sport where professional rugby players are exposed to considerable training and game loads in pre-season and in-season. Some studies have shown that rugby players' dietary intake remains inadequate for the three macronutrients (carbohydrates [CHO], proteins and fats) required for optimal performance. This study aimed to describe the macronutrient intake of professional male rugby players at Zebre Rugby Club in Parma, Italy, during in-season, and to compare players' macronutrient intake to international recommendations. METHODS: Thirty-four professional male rugby players participated in the cross-sectional study. A self-developed questionnaire, a food frequency questionnaire and food records (on training and competition days and off day) were used to investigate players' macronutrient intake. Anthropometric measurements were obtained using the International Society for the Advancement of Kinanthropometry (ISAK) standardized techniques. Descriptive statistics were calculated, and associations were investigated using chi-square, Fisher's exact and Wilcoxon rank tests as applicable. RESULTS: The players' median age was 25.8 years (range 20.6-33.0 years) and 47.5% were Italian. Most players (64.7%) held forward positions and had a median of 5 years (range 2-14 years) of professional experience. More than 75.0% of players lived with a spouse or partner and 30.3% earned between 4 000-4 999 euros per month. The median body weight and height of players were 106.9 kg and 186.3 cm, respectively. The forwards weighed heavier ( < 0.0001) than the backs, which was expected due to positional demands, with no significant difference in height distribution. The median body mass index ( < 0.0001), waist circumference ( < 0.001) and waist-to-height ratio ( < 0.03) of forwards were higher than the backs. Additionally, the median body fat percentage of all players exceeded the international recommendation of 8-17% for rugby union players. The American College of Sports Medicine (ACSM), International Olympic Committee (IOC) and International Society of Sports Nutrition (ISSN) recommend an intake of 5.0-8.0 g/kg body weight (BW)/day CHO, 1.5-2.0 g/kg BW/day proteins and 20-35% total energy (TE) from fats for rugby players. The overall median intake of the three-day food records for all the players was 2.7 g/kg BW CHO, 1.7 g/kg BW protein and 35.1% TE from fat. On each of the three reported days, 90.0% of players' CHO intake fell below the recommended range, with almost all players (>90.0%) consuming less than the recommended amount of carbohydrates and almost 30.0% of players consuming below the recommended amount of protein on competition day. At least 50.0% of players' protein and fat intake was within the recommended range on each of the three reported days. CONCLUSION: The study's findings can assist various stakeholders at Zebre Rugby Club to align rugby players' dietary requirements to their workload, and encourage players' adherence to dietary guidelines and recommendations. It is advised that attention be focused on accurate dietary education, intake and monitoring to promote individualization and optimal performance and recovery. Future research is needed to adapt standardized macronutrient recommendations for rugby-specific requirements and address obstacles that may impede the optimal intake of macronutrients.
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