This exploratory study examined the effect of carbohydrate and subsequent energy availability (EA) on training adaptations, health, and sleep metrics across a 7-week preseason in semiprofessional female rugby union athletes. Full food provision on training days (four/week) manipulated carbohydrate intake: 6 versus 3 g·kg-1·day-1 for intervention (n = 7) and CON (n = 6), respectively while standardizing protein intake (>1.2 g·kg-1·day-1). Nontraining days involved ad libitum intake. Quantification of exercise energy expenditure via an individually calibrated wearable device allowed estimation of EA. Strength (three-repetition max squat, bench pull, and bench press), Bronco shuttle time; countermovement jump; biomarkers including iron studies, thyroid function, and cholesterol; sleep metrics; and physique (four-compartment model) were assessed before and after preseason. Training day carbohydrate intake was higher in intervention than CON (6.3 ± 0.2 vs. 3.1 ± 0.2 g·kg-1·day-1, p < .001), resulting in higher EA across the preseason (45.0 ± 5.8 vs. 29.9 ± 5.8 kcal·kg-1 fat-free mass-1·day-1, p < .001). Significant time effects were observed for bench pull (+3.6 kg, p = .024) and bench press (+4.6 kg, p = .011), fat mass (-1.1 kg, p < .001), fat-free mass (+1.2 kg, p = .025), and ferritin (-29 μg/L, p = .009). No significant interaction was observed for training adaptations, physique, or biochemical markers. Greater sleep duration was observed in CON on training nights, F(1, 156.072) = 5.821, p = .017, although other sleep metrics showed limited between-group differences. While increased carbohydrate intake improved EA, it had limited effect on training adaptations, health, or sleep metrics in this small, exploratory cohort.
Exercise in the heat perturbs human physiology through elevated core temperature, fluid loss, and cardiovascular strain. While fluid intake can mitigate these effects, the electrolyte composition of hydration solutions may improve rehydration efficacy. This study evaluated whether hydration strategy modulates thermal strain, inflammation, and performance during and after exercise in a hot environment, comparing three different fluid solutions: water, sodium-potassium drink, and coconut water. Twelve participants (seven males) completed a randomized, triple-blind crossover trial. Measures included handgrip strength, countermovement jump, tympanic temperature, thermal sensation, discomfort, body mass, body water percentage, heart rate, and total leukocyte count. Participants were randomly assigned 300 ml of one of three solutions before cycling for 60 min at 1.5 W/kg in ∼33 °C conditions. Additional 300-ml doses were consumed postexercise at 0, 30, and 60 min; measures were taken at each time point before solution consumption and at 90-min postexercise. Following exercise in the heat, a significant main effect for time was observed for all outcomes: thermal responses, heart rate, body mass and body water (p < .001); fatigue (p < .001); and leukocyte count (p = .016), indicating a strong physiological response to heat stress. However, no significant differences were observed between hydration strategies (p ≥ .152) for all measures. In conclusion, exercise in the heat elicited significant thermal strain, fatigue, and inflammation, independent of hydration strategy. Electrolyte composition did not significantly alter responses when fluid intake was controlled, highlighting the need for further research.
Athletes report consuming nutritionally dense foods before and during exercise to manage gastrointestinal symptoms (GIS). The study investigated whether fat, compared with carbohydrate (CHO), as a gut-training supplement, compromises gastrointestinal integrity and triggers systemic inflammation in response to endurance exercise. Thirty-six endurance athletes (seven females and 29 males) completed a preintervention gut-challenge trial (T1), involving a 2-hr run (60%V˙O2max) with CHO gel intake every 20 min (87 g/hr), followed by a 1-hr self-paced distance test. Participants were randomized to a fat (FFC; 20 g nut butter) or CHO supplement (CFC; 47 g CHO gel) for a feeding-challenge protocol (1 hr exercise with supplement for 7 days), followed by a gut-challenge retrial (T2). During T1 and T2, blood samples were collected before and after exercise to measure intestinal fatty-acid binding protein (I-FABP), soluble CD14 (sCD14), and C-reactive protein (CRP). Pre- to postexercise peak responses were similar within and between groups for plasma I-FABP (FFC: 254 ± 495 vs. 349 ± 622 pg/ml, p = .911; CFC: 344 ± 336 vs. 421 ± 362 pg/ml, p = .501; between groups T1: p = .404; T2: p = .440) and sCD14 (FFC: 0.346 ± 0.703 vs. 0.175 ± 0.603 μg/ml, p = .509; CFC: 0.336 ± 0.522 vs. 0.546 ± 0.777 μg/ml, p = .587; between groups T1: p = .888; T2: p = .149). CRP was significantly reduced in CFC (0.327 ± 0.449 vs. 0.062 ± 0.231 μg/ml, p = .030) but not in FFC (p = .351). Total-GIS severity during exercise or recovery were not correlated with I-FABP, sCD14, and CRP. The repetitive feeding-challenge with fat, compared with CHO, did not increase markers of gastrointestinal injury, bacterial endotoxin translocation, and systemic inflammation in response to endurance exercise.
We examined factors that inform iron-deficiency screening practices in female athletes, with a focus on the menstrual cycle. Twenty-four National Rugby League athletes attended a 5-week training camp (age 21.6 ± 3.4 years old, body mass: 76.3 ± 12.1 kg, height: 164.9 ± 4.6 cm). Athletes were either naturally cycling (athleteNC; n = 11) or using hormonal contraception (athleteHC; n = 13). Venous blood samples were collected during Phases 1, 2, and 4 of the menstrual cycle in athleteNC for determination of iron status. Three equally spaced, corresponding time points were sampled in athleteHC. Every 48 hr, a capillary blood sample was collected and analyzed for ferritin, hepcidin, creatine kinase, and C-reactive protein. No differences across menstrual phases or groups were evident for ferritin, hepcidin, transferrin or hemoglobin (p > .05). Serum iron (12.9 ± 4.6 μmol/L to 16.9 ± 8.5 μmol/L; p = .045) and transferrin saturation (17.3% ± 7.8% to 22.1% ± 14.5%; p = .041) increased from Phase 1 to Phase 2 in athleteNC only, with no change seen in athleteHC. Ferritin (-16%; p < .001) and hepcidin (-23%; p < .001) declined across the training camp in all athletes. Concentrations of C-reactive protein (p = .039) were consistently higher in athleteHC compared with athleteNC, whereas creatine kinase activity were similar between groups (p = .140). Our findings did not identify clear menstrual cycle phase-related differences in markers of iron status or regulation, suggesting that the influence of cycle phase may be relatively small compared with other sources of variation. Practitioners should be mindful that athletes using hormonal contraceptives may report with greater C-reactive protein concentrations than naturally cycling athletes.
Athletes in weight category sports frequently practice short-term weight loss to make weight, which often involves manipulating total body water. In Eastern medicine and phytotherapy, dandelion has long been considered to have a diuretic effect, yet empirical investigations of this effect are scarce. This study investigated whether the ingestion of a commercially available dandelion root powder with a large bolus of water acutely elicited a diuretic effect beyond the effect on urine output elicited by the bolus of water alone. In an open-label counterbalanced, crossover design with two separate laboratory visits, physically active young adults (n = 14; M/F, 12/2; age, 25.5 ± 4.7 years) ingested 1 L of still water with (DAND) or without (CON) four capsules providing a total of ∼2.1 g of a commercially available dandelion root powder. The primary outcome was cumulative urine output over the 4 hr following ingestion. Cumulative urine output was 1,164 ± 244 g in CON and 1,268 ± 213 g in DAND, with the mean difference (95% confidence interval) of 105 (-35 to 244) g (p = .13; g = 0.45). Under the experimental protocol employed, the commercially available form of dandelion ingested, the dosing strategy used, and the cohort investigated, cumulative urine output was similar regardless of whether dandelion root powder was co-ingested with a large bolus of water. These results indicate a lack of support for the purported diuretic effect of dandelion. Future studies should investigate different time courses, dosing strategies, and sources of dandelion, as well as study designs with greater ecological validity for weight category sports, before definitive conclusions can be made.
Ice hockey is a high-intensity intermittent team sport where games of 3 × 20-min periods involve on-ice shifts (typically lasting ∼30-80 s) interspersed with passive recovery periods (2-5 min). Playing requires endurance, speed, strength, and balance in conjunction with technical, tactical, and cognitive abilities. Nutrition can play a valuable role in optimizing physical and mental performance and in maintaining overall health of ice hockey players. The aim of this review is to provide evidence-based nutrition guidelines for elite male ice hockey players. The energy demands during training sessions and games in ice hockey are not well investigated, but elite players typically cover 2.3-6.7 km in their 15-25 min of on-ice time during games. Carbohydrate (primarily muscle glycogen) is the major fuel during training and match play, and match performance has been shown to be associated with the pregame muscle glycogen content. Sweat losses are typically high (2.02 ± 0.74 L/hr) due to the high intensity and the use of protective equipment. Sufficient carbohydrate and fluid intake are therefore the most important nutritional considerations during training sessions, games, and recovery to maintain performance. Protein intake is important after training sessions and games to support muscle repair, growth, and overall recovery. Nutrition plans should be personalized and periodized to meet the demands of training sessions and games, and individual objectives. Players should prioritize food before supplements to meet nutrient requirements. While studies on supplementation are scarce, supplements that might be beneficial to some ice hockey players include Vitamin D, iron, caffeine, and creatine.
Carbohydrate loading (CL) has long been a cornerstone of endurance nutrition, yet its true efficacy remains uncertain. Although CL is commonly associated with improved time to fatigue and modest performance gains in exercise lasting ∼90-240 min, few studies have employed double-blind, placebo-controlled (DBPC) designs. Given that belief and expectation can independently influence performance, it remains unclear whether reported benefits reflect CL or placebo effects. We systematically evaluated the use of blinding and in-exercise carbohydrate provision in CL research. Of 14 identified studies, only two were DBPC trials. Notably, only four provided carbohydrates during exercise. Both DBPC studies included appropriate in-exercise carbohydrate intake and reported no evidence of performance benefit of CL. Of the remaining two studies that provided carbohydrates during exercise, CL showed a positive performance effect; however, the effect size was moderate and comparable to that reported for placebo nutritional interventions (Cohen's d ≈ 0.35). Comparisons across CL studies are heterogeneous in design, including differences in performance test type (time to exhaustion vs. time trial), which points to the need for more research in standardized conditions. The current evidence therefore calls for a re-evaluation of whether CL in the 24-48 hr before competition enhances performance once placebo effects are accounted for and in-race fueling is optimized. This commentary highlights the need for more DBPC studies and the potential role of placebo (such as belief) in observed performance outcomes. We propose future research directions to better isolate the independent contributions of CL and placebo effects in endurance performance.
Exercise-induced muscle damage (EIMD) impairs muscle function and subsequent performance. While research investigating the protective role of animal-derived protein is widespread, investigations into sustainable alternatives are lacking. The present study examined the effects of a novel, salmon-derived protein peptide (SPP) on muscle recovery. In a single-blind, parallel-design, 33 recreationally active adults (age: 23.9 ± 4.0 years, body mass index: 23.7 ± 4.0) were randomly assigned to one of three groups: (a) SPP, (b) whey protein, or (c) carbohydrate control. In addition to a controlled 1.0 g·kg body mass-1·day-1 dietary protein intake, participants consumed either 0.9 g·kg body mass-1·day-1 supplemental protein or isoenergetic carbohydrate for 4 days following EIMD (10 × 10 unilateral eccentric knee extensions). Maximal voluntary contraction, countermovement jump height, muscle soreness, thigh circumference, creatine kinase, and lactate dehydrogenase were assessed at baseline and +1, +4, +24, +48, and +72 hr post EIMD. Significant time effects were observed for all variables. Countermovement jump height was greater in the SPP versus carbohydrate groups at +72 hr and across all time points when pooling the two protein groups, creating a higher protein versus normal protein group comparison. There were no significant group effects for all remaining outcomes. High-quality protein supplementation >1.0 g·kg body mass-1·day-1 appears to have only a modest effect on the rate of recovery following EIMD, with a potential role in alleviating muscle damage, particularly in the later stage of recovery. Furthermore, the SPP supplement was not inferior to a high-quality protein source (whey protein), indicating that it may represent a sustainable and effective alternative for muscle recovery.
This systematic review and meta-analysis aimed to determine the effect of caffeine ingestion on female cycling performance. Three databases were systematically searched; studies were screened according to PICOS framework and PRISMA guidelines. Data were analyzed using a three-level meta-analytical model to account for the nesting of multiple performance outcomes within individual studies. Subgroup analyses assessed the influence of caffeine dose, training level, and menstrual cycle phase. Risk of bias was assessed using the RoB 2 tool; heterogeneity was assessed using the Q test and funnel plot analysis. Nineteen randomized crossover trials involving 235 females were included. The pooled analysis revealed a small and significant ergogenic effect of caffeine supplementation on cycling performance for females (standardized mean difference = 0.21; 95% confidence interval [0.11, 0.29]), with high certainty of evidence. Subgroup analysis showed a nonsignificant effect for caffeine dose ( p = .79) and training level ( p = .97), while caffeine significantly improved performance during the mid-luteal phase (standardized mean difference = 0.26; 95% confidence interval [0.06, 0.46]; p = .01) with no effect for other menstrual cycle phases ( p > .11). Heterogeneity was nonsignificant, Q (36) = 7.99; p = 1.00, and overall risk of bias was rated as “some concerns.” The limited clinical trials and inadequate menstrual cycle assessments preclude definitive conclusions regarding the effect of the menstrual cycle phases. These findings support the supplementation of caffeine to optimize performance in cycling for women.
It is recommended that endurance athletes modulate their daily carbohydrate intake according to the demands of training, but there is limited evidence of how this is currently practiced by athletes during real-world, day-to-day training. The purpose of this observational study was to report the dietary intake of endurance athletes across a 12-week period with an emphasis on the relationship between training load and carbohydrate intake. Self-selected training and dietary intake were self-reported using a smartphone app by 46 endurance athletes (61% male) daily for 12 weeks, representing a total of 3,718 days of dietary assessments and 3,160 days of training. Fasted-state training was regularly performed by 65% of athletes and was more common in men (33.6% vs. 17.2% of training days, p = .023). Average daily carbohydrate intake for each athlete ranged from 1.2 to 7.2 g/kg (M = 3.9 ± 1.5). At the group level, significant correlations were found between mean daily carbohydrate intake and both percentage of training sessions performed in the fasted state (r = -.39, p = .008) and weekly training volume (r = .42, p = .004). Participant-level correlations between daily training load and carbohydrate intake ranged from -.42 to .83. Overall, athletes adjust daily carbohydrate intake based on exercise duration, but at the individual level, many athletes do not align carbohydrate intake with training load as recommended or do so with minimal adjustment.
The International Standards for Anthropometric Assessment (International Society for the Advancement of Kinanthropometry [ISAK]) have been developed and refined over a period of over 30 years in order to guide the landmarking and measurement of a wide range of surface anthropometrical variables in able-bodied individuals in order for such measures to be reliable, repeatable, and valid. While numerous researchers and practitioners have undertaken anthropometrical assessments on individuals with motor disability, there is a lack of consistency in the processes used, and the ISAK protocol currently does not guide adaptations for measurement or interpretation in this population. Therefore, the ISAK working group on motor disability has reviewed the literature and provided recommendations to follow when undertaking and interpreting anthropometrical assessments in individuals with a motor disability. Prior to undertaking any assessment, practitioners and researchers are encouraged to first consider the purpose and validity of what they wish to measure in each individual, as they present with their own unique characteristics. Most importantly, the safety and dignity of each individual must be respected.
The study aimed to examine the independent and combined effects of a 90-min early afternoon (12:30 p.m.) nap (NAP) and an early evening (6:00 p.m.) moderate dose of caffeine (CAF; 5 mg/kg) on afternoon's variation of subjective sleepiness and reaction time and evening (7:00 p.m.) physical performance. In a randomized, counterbalanced, and double-blind design, 13 physical education students completed four conditions separated by 3-7 days: placebo (PLA), NAP, CAF, and combined nap plus caffeine (NAP + CAF). Assessments included simple and choice reaction times and the Epworth Sleepiness Scale at 12:30 p.m., before napping/resting, and every hour between 3:00 p.m. and 7:00 p.m. Jumping performance (squat jump and countermovement jump) and the repeated modified agility test were assessed once at 7:00 p.m. No significant effects of CAF, NAP, and CAF + NAP on simple reaction time, choice reaction time, and Epworth Sleepiness Scale were found. Repeated modified agility test performance improved across all interventions compared with PLA, with no difference between interventions. All interventions enhanced squat jump performance relative to PLA, with the greatest improvements observed under NAP + CAF compared with CAF (p < .05, d = 0.37, mean difference [MD] = 1.92 cm; p < .05, d = 0.38, MD = 0.07 m/s; p < .05, d = 0.01, MD = 0.01 W/kg) and NAP (p < .01, d = 0.63, MD = 2.91 cm; p < .01, d = 0.68, MD = 0.11 m/s; p < .01, d = 0.02, MD = 0.02 W/kg), respectively, for squat jump, take-off velocity, and relative power. Napping and caffeine independently enhanced repeated agility and explosivity performances, and their combination had no additional benefits on repeated agility. However, the combination further enhanced explosivity, which may benefit evening competitions in team and racket sports. Its limited effects on nonexplosive tasks and potential sleep disruption constrain broader application.
Discrete time-series measurements collected at predefined timepoints are widely used in sport nutrition and exercise metabolism research, including tolerance tests, tracer studies, and physiological responses to experimental interventions. These data sets are commonly summarized using derived metrics such as area under the curve. The original Time Series Response Analyser, introduced in 2020 as a spreadsheet-based tool, aimed to standardize these calculations and reduced the risk of manual errors. However, spreadsheet implementations can be difficult to maintain, extend, and version control, and provide limited transparency regarding exactly how outputs are derived. Here, we present Time Series Response Analyser v2.0, a web-based successor designed to improve accessibility, usability, and long-term maintainability while preserving the analytical purpose of the original tool. The application runs in a standard web browser and guides users through a structured workflow consisting of data setup, file interpretation screening, interactive analysis, and export of results. It retains the core summary metrics of the original version while expanding visualization capabilities and export options. In summary, Time Series Response Analyser v2.0 is a free, open-source web-based application for researchers analyzing discrete time-series experiments across both repeated-measures and independent-groups designs, supporting transparent and reproducible analytical workflows while enabling future development through a code-based platform.
Beetroot juice (BRJ) has been proposed as an ergogenic aid due to its high nitrate content, yet evidence from field-based studies in elite swimmers remains limited. This study investigated the acute effects of concentrated BRJ ingestion on performance and physiological responses during repeated maximal 200-m front-crawl efforts in elite male swimmers. Twelve elite swimmers (age: 20 ± 2 years, body fat: 7.1% ± 2.5%, 200-m personal best: 115.7 ± 3.4 s) completed a randomized, double-blind, counterbalanced trial. Participants consumed either 140 ml of concentrated BRJ (Beet It Sport) or a custom-made, nitrate-depleted placebo (PL) matched for sensory characteristics, 2 hr before performing two maximal 200-m front-crawl time trials, separated by 60 min of passive recovery. Blood samples were collected upon arrival and immediately after each time trials, and 200-m completion time, blood lactate concentrations, and ratings of perceived exertion were recorded. No significant differences were observed in completion time for either the first (PL: 116.7 ± 3.0 vs. BRJ: 117.2 ± 3.1 s, p = .19) or the second 200-m time trial (PL: 117.8 ± 2.6 vs. BRJ: 117.8 ± 3.3 s, p = .98), nor in the change between trials (PL: 1.1 ± 1.5 vs. BRJ: 0.5 ± 1.3 s, p = .40). Likewise, lactate concentrations and ratings of perceived exertion values did not differ between conditions (p > .05). In conclusion, acute BRJ supplementation did not enhance 200-m front-crawl performance, lactate responses, or perceived exertion in elite swimmers under competition-like conditions.
BACKGROUND:Water turnover (rH2O) is related to water balance including preformed water intake (WI), metabolic, inspired, and transcutaneous water. Literature is scarce on athletes. This study aimed to estimate and compare rH2O and its components during one athletic season (preparatory and competition phases), adjusting for body composition and energy expenditure (EE). METHODS:This longitudinal observational study included 112 athletes (19.8 ± 4.9 years, 39 females). Doubly labeled water determined total EE, rH2O, and the remaining components through specific equations. Total body water was determined by deuterium dilution and fat-free mass by the four-compartment model. Resting EE was assessed by indirect calorimetry. RESULTS:During the preparatory phase, male athletes showed higher rH2O [5.03 (0.14) kg/day] compared with females [3.64 (0.19) kg/day, p < .001], even adjusting for body mass (p = .024), but not for fat-free mass, total body water, and EE. Triathletes showed higher values of rH2O after adjustments (p < .05). Over the athletic season, no changes occurred for rH2O or preformed WI within or between sexes or sports, even adjusting for body composition while some changes occurred adjusting for EE (p < .05). Over the season, metabolic water increased (p < .001), while inspired and transcutaneous water showed both increases and reductions (p < .05). A small prevalence (∼16%) of low WI (WI ≤ 35 ml/kg of body mass/day) was persistent in both timepoints. CONCLUSION:While rH2O and preformed WI did not differ over the season, cross-sectional differences were observed between sports but not between sexes, highlighting the variability of rH2O and impact of contributing factors. Low preformed WI was present throughout the athletic season.
Although dietary fiber is widely recognized for its health benefits in the general population, including reduced risk of cardiovascular disease and improved metabolic regulation, its role in athletic performance and recovery remains comparatively underexplored. Current sports nutrition guidelines lack specific recommendations for fiber intake, despite evidence linking adequate consumption to gut microbiome stability, immune modulation, and body composition optimization. Athletes face unique physiological demands that influence gastrointestinal tolerance, nutrient absorption, and energy availability, particularly under high training loads. Although excessive fiber intake may lead to gastrointestinal discomfort or reduced caloric intake, moderate and periodized consumption has been associated with enhanced immune function, improved energy metabolism, and preservation of skeletal muscle mass. Recent findings suggest potential benefits in attenuating exercise-induced inflammation and regulating substrate utilization. Nevertheless, observational data indicate that many athletes fail to meet general population intake targets, often due to precompetition dietary restrictions or concerns about digestive comfort. This review critically synthesizes current evidence on the physiological impacts of dietary fiber in athletic populations, focusing on gastrointestinal health, immune function, body composition, and performance outcomes. It further outlines practical, evidence-based strategies to optimize intake according to individual needs and sport-specific demands, including fiber periodization, source selection, and gradual adaptation.
In elite road cycling, nutrition is a critical pillar of performance, with culinary support evolving from a logistical necessity to a core competitive determinant. The collaboration among performance chefs, registered dietitian/nutritionist(s), and soigneurs, collectively termed the Culinary Nutrition Team, is central to translating evidence-based nutrition strategies into practical, palatable food provision. Through an applied lens, this review positions the Culinary Nutrition Team as the operational link through which complex nutrition, physiological, and sport science principles are translated and delivered in day-to-day practice within professional road cycling. The overlapping skill sets of Culinary Nutrition Team members are described, alongside respective roles and responsibilities, in executing nutrition strategies through real-time menu adjustments, management of special dietary needs, and adaptation to environmental and logistical challenges. While common principles underpin effective culinary nutrition support, how those principles are executed in practice is shaped by practitioner training and scope of practice, team structure and maturity, communication pathways, staff dynamics and trust, and the broader cultural and logistical context in which teams operate. In this context, digital tools and technologies (e.g., workload-derived data integration, centralized nutrition management platforms, and biometric wearables) are gaining prominence as innovative approaches to inform energy requirements, support rapid food provision adjustments, and facilitate team-wide communication. However, their effectiveness depends on appropriate validation, integration within established workflows, regulatory approval for in-race, and skilled interpretation. Ultimately, an athlete-centered, systems-based approach to culinary nutrition support embedded within the wider performance team is no longer a marginal gain but a competitive necessity in modern professional road cycling.
