International journal of sport nutrition and exercise metabolism最新文献

{"title":"UCI Sports Nutrition Project: Considerations and Applications for the Use of Sports Foods and Supplements to Improve Performance in Cycling.","authors":"Jamie Whitfield, Brendan Egan, Juan Del Coso, Wim Derave, Bryan Saunders, Louise M Burke","doi":"10.1123/ijsnem.2025-0111","DOIUrl":"10.1123/ijsnem.2025-0111","url":null,"abstract":"<p><p>The use of sports foods and supplements has become ubiquitous among cyclists of all disciplines in order to meet energy and nutrient targets and to improve performance and recovery outcomes. This review will provide an overview of the different types of products and the rationale for their use, while highlighting key considerations surrounding the safety and anti-doping risks that supplements pose among athletes. A summary of supplements with a strong evidence base (caffeine, creatine, sodium bicarbonate, beta-alanine, dietary nitrate, and glycerol) and emerging supplements popularized within cycling (exogenous ketones) is also provided, outlining accepted protocols for use, timing, and potential ergogenic effects or side effects.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"187-214"},"PeriodicalIF":2.5,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146029460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Acute Alcoholic Beer Dose Impaired Exercise Performance: A Double-Blind, Placebo-Controlled Crossover Trial.","authors":"Felipe De Russi de Lima, Vitor de Salles Painelli, Raul Canestri, Tony Meireles Santos, Flávio Oliveira Pires","doi":"10.1123/ijsnem.2026-0095","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0095","url":null,"abstract":"<p><strong>Purpose: </strong>We investigated whether a small dose of alcoholic beer ingested before a running exercise bout impaired performance and changed psychophysiological responses to exercise.</p><p><strong>Methods: </strong>After three sessions of familiarizations, 16 healthy and physically active men (25.8 ± 5.1 years, 175.0 ± 5.4 cm, and 76 ± 6.5 kg) performed a 30-min running time trial in a double-blind and placebo-controlled crossover design, after ingesting either beer (alcohol 4.8% v/v; 0.3 g/kg) or nonalcoholic beer (placebo). Performance, cardiopulmonary (oxygen consumption, ventilation, respiratory exchange ratio, and heart rate), and perceptual (perceived exertion, affect, and motivation) variables were assessed throughout the trial and averaged every 5 min during exercise. Running economy was assessed during steady-state running at 8 km/hr. The data were analyzed through t tests and repeated-measures mixed models (p < .05).</p><p><strong>Results: </strong>The ingestion of beer significantly decreased the average speed by 4.7% (p = .04; d = 0.21) and total distance covered by 4.3% (p = .007; d = 0.26) when compared with placebo. The ingestion of beer also impaired the running economy by 1.1% (p = .01; d = 0.39) and increased respiratory exchange ratio throughout the exercise bout (p = .004, d = 1.07). No beer-by-time interaction effects were detected in cardiopulmonary outcomes (p > .05).</p><p><strong>Conclusions: </strong>A small dose of alcoholic beer reduced the exercise capacity of healthy individuals, likely due to an impairment in running economy.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-10"},"PeriodicalIF":2.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149206901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acute and Chronic L-Carnitine Supplementation Enhances Endurance Performance Without Consistent Effects on Substrate Oxidation in Active Individuals: A Systematic Review.","authors":"Hilal Eryiğit, Yasemin Güzel, Süleyman Bulut, Hüseyin H Turnagöl, Muhammed M Atakan","doi":"10.1123/ijsnem.2026-0077","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0077","url":null,"abstract":"<p><strong>Objectives: </strong>This study aims to systematically evaluate the effects of acute and chronic L-carnitine supplementation on endurance performance and substrate oxidation during exercise among active individuals.</p><p><strong>Methods: </strong>This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. A total of 647 studies were initially retrieved from PubMed/MEDLINE, Web of Science, Cochrane Library, Scopus, Ovid MEDLINE, EBSCO Open Dissertations, EBSCO Academic Search Ultimate, and SPORTDiscus databases, with searches conducted from database inception to February 1, 2026. Randomized placebo-controlled crossover and parallel-group trials were eligible for inclusion. Studies meeting the inclusion criteria were assessed using the Cochrane Risk of Bias 2 (RoB 2) tool, with the crossover-specific version applied to randomized crossover trials.</p><p><strong>Results: </strong>A total of 18 studies met the inclusion criteria. Overall, 15 (83%) studies were rated as having some concerns, three (17%) were classified as having a high risk of bias, and none were judged to be at low risk of bias. Ten studies investigated acute L-carnitine supplementation (2-15 g), seven studies examined chronic supplementation (2-3 g/day for 2-24 weeks), and one study evaluated both acute and chronic supplementation (3 g on a single day and over 2 weeks). Both acute and chronic L-carnitine supplementation were associated with improvements in endurance performance following acute supplementation and chronic supplementation. By contrast, no significant changes in fat oxidation during exercise were reported after either acute (2-4 g ingested 120-180 min before exercise) or chronic supplementation (2 g/day for 2-4 weeks).</p><p><strong>Conclusions: </strong>L-carnitine may enhance selected endurance performance outcomes among active individuals; however, its reputation as a \"fat-burning\" ergogenic aid is not supported by current evidence, following short-term supplementation.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-13"},"PeriodicalIF":2.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149206896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Summary of the 2026 Professionals in Nutrition for Exercise and Sport \"10 Questions/10 Experts\" Session-Are Sports Nutrition Guidelines Too Elite Focused for Recreational Athletes?","authors":"Thorben Aussieker, Louise M Burke, Judith Haudum, John A Hawley, D Enette Larson-Meyer, Melinda M Manore, Jason C Siegler, Trent Stellingwerff, Anni Vanhatalo, Žan Zupančič, Floris C Wardenaar","doi":"10.1123/ijsnem.2026-0168","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0168","url":null,"abstract":"<p><p>This article provides a synopsis of the 10 Questions/10 Experts session at the 2026 American College of Sports Medicine Annual Meeting, which examined whether sports nutrition guidelines are equally applicable from recreational to elite athletes. Each speaker considered the validity of a given common \"myth\" statement and provided an evidence-based opinion to support, bust, or qualify propositions addressing the following questions: (a) Are sports nutrition guidelines based primarily on studies of elite athletes, and are they too serious for recreational athletes? (b) Do recreational marathon runners need the same in-race carbohydrate recommendations as elite marathon runners? (c) Must recreational athletes consume 1.6 g·kg-1·day-1 of protein to benefit from exercise training? (d) Does nitrate supplementation benefit elite and recreational athletes equally? (e) Do recreational athletes need a structured fluid intake plan? (f) Is sodium bicarbonate loading relevant only to elite athletes? (g) Do recreational and elite athletes require more micronutrients than suggested by the Recommended Dietary Allowances? (h) Is eating after 8:00 p.m. detrimental to performance or recovery in recreational athletes? (i) Are recreational athletes at greater risk for suboptimal vitamin D status because indoor occupations reduce sunlight exposure? and (j) Should recreational athletes train with low carbohydrate availability to amplify adaptation? This article describes the content of each presentation, including the most important evidence, practical implications, and conclusions identified by the presenters.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-10"},"PeriodicalIF":2.5,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149206826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Individual Calibration of a Multiinput Wearable Device Improves Exercise Energy Expenditure Estimation During Intermittent High-Intensity but Not Resistance Exercise in an Athletic Female Population.","authors":"Rebekka Frazer, Christopher D Askew, Amy-Lee Bowler, Louise M Burke, Dominique Condo, Gregory R Cox, Krist Feka, Shona Halson, Alexander H K Montoye, Fiona Pelly, Jonathon Weakley, Gary Slater","doi":"10.1123/ijsnem.2026-0088","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0088","url":null,"abstract":"<p><p>This study aimed to determine the accuracy of a multiinput wearable device (Actiheart 5) and commercially available accelerometer (GENEActiv) in the estimation of exercise energy expenditure (EEE) during intermittent high-intensity and resistance exercise sessions among 31 trained females. Data were collected over two testing sessions involving (a) measurement of resting metabolic rate, physique and a graded exercise test on a treadmill to enable individualized calibration of the wearables, and (b) A modified Bath University Rugby Union Shuttle Test followed by a resistance exercise session. GENEActiv and Actiheart EEE-derived measures, using both generic and individually calibrated algorithms, were compared against (a) indirect calorimetry for Bath University Rugby Union Shuttle Test and (b) indirect calorimetry plus the estimated anaerobic energy contribution based on blood lactate responses for resistance exercise. Equivalence was evaluated using predefined bounds of ±10% mean indirect calorimetry EEE. The use of individually-calibrated Actiheart algorithms improved estimation of EEE during Bath University Rugby Union Shuttle Test (mean bias 4.5 ± 60.4 kcal) compared with individually-calibrated GENEActiv algorithms (mean bias 69.5 ± 86.6 kcal), and equivalence with indirect calorimetry was achieved, although substantial individual error remained (95% limits of agreement -113.9 to 122.8 kcal and intraclass correlation coefficients, .62 [.34 to .80]). Individualized Actiheart algorithms provided equivalent group-level estimates of EEE during intermittent high-intensity exercise, whereas neither Actiheart nor GENEActiv demonstrated acceptable validity or equivalence against the reference method for resistance training, suggesting Metabolic Equivalents of Task may be a more practical method of estimating EEE.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-13"},"PeriodicalIF":2.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Caffeine Intake on Fat Oxidation During and After Aerobic Exercise in Women Using Oral Contraceptives: A Randomized, Double-Blind, Crossover Trial.","authors":"Megumi Wanifuchi, Aiko Miyaguchi, Jua Hiramatsu, Hana Yamase, Kayoko Kamemoto, Tomoka Matsuda, Mizuki Yamada, Mikako Sakamaki-Sunaga","doi":"10.1123/ijsnem.2026-0081","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0081","url":null,"abstract":"<p><p>Despite extensive research on the effects of caffeine intake on fat oxidation during and after aerobic exercise, its effects on women using oral contraceptives (OCs) remain unclear. This study investigated the effects of caffeine intake on fat oxidation during and after aerobic exercise in women using OCs. This study included 13 sedentary women using OCs. The subjects completed three consecutive 10-min bouts of cycling at 40% peak oxygen uptake separated by 10-min rest periods. Each session was conducted 60 min after intake of either caffeinated coffee (CAF; 5 mg/kg) or decaffeinated coffee (CON) in a randomized, double-blind, crossover design. Serum caffeine concentrations were measured before intake, preexercise, immediately postexercise, and 30, 60, and 90 min postexercise. Fat oxidation was measured before intake, preexercise, during exercise (EX1 and EX2), immediately postexercise, and 30, 60, and 90 min postexercise. The serum caffeine concentration in the CAF was significantly higher than that in the CON preexercise, immediately postexercise, and 30, 60, and 90 min postexercise (all p < .001). Fat oxidation in the CAF was significantly lower than that in the CON before intake (p < .05) but higher than that in the CON immediately postexercise (p < .05). The change in fat oxidation in the CAF was significantly higher than that in the CON at preexercise, EX1, immediately postexercise, and 30, 60, and 90 min postexercise (all p < .05). This study suggests that caffeine intake before exercise enhances fat oxidation during and after exercise in women taking OCs.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-9"},"PeriodicalIF":2.5,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148976928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"UCI Sports Nutrition Project: Position Statement on Nutrition for Cycling.","authors":"Louise M Burke, Eimear Dolan, Javier T Gonzalez, Iñigo Mujika, Asker E Jeukendrup, Martijn Redegeld, Gabriel Martins, Pedro L Valenzuela, Peter Leo, Manuel Mateo-March, Gabriele Gallo, Stephen Seiler, James P Morton, Mark Hearris, Marc J Fell, Daniel J Owens, Shona Halson, Jorn Trommelen, Jamie Stanley, Eric Haakonssen, Jill J Leckey, Kellie Hogan, Kerry O'Bryan, Tanja Oosthuyse, José J Muros, Mikel Zabala, Luuk Hillkens, Jan-Willem van Dijk, Jose L Areta, Megan A Kuikman, Alexandra M Coates, David M Bailey, James Moran, Patrick B Wilson, David B Pyne, Adrian Rotunno, Brendan Egan, Juan Del Coso, Wim Derave, Bryan Saunders, Simon Helleputte, Teun van Erp, Daniel Green, Tim Podlogar, Stephen S Cheung, Lars Nybo, Olivier Girard, Trent Stellingwerff, Dana M Lis, Nicki Strobel, Xavier Bigard, Jamie Whitfield","doi":"10.1123/ijsnem.2026-0135","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0135","url":null,"abstract":"<p><p>Nutrition is a key determinant of cycling performance, underpinning the ability to optimize on-bike performance, support training adaptation and recovery, and maintain rider health and well-being. While these goals are shared across disciplines, the diverse physiological demands and logistical constraints of different cycling disciplines present distinct nutritional challenges. In recognition of both the importance of nutrition and the diverse individual and discipline-specific demands of cycling, the Union Cycliste Internationale Sports Nutrition Project was established and led by a steering committee that synthesized the expertise of 54 researchers to identify key nutritional requirements for elite cycling and develop recommendations that account for both individual and discipline-specific needs. These insights were published within a series of 14 topic-specific reviews. In this position statement, we present the principal take-home messages from the overall project, organized into 10 overarching themes spanning performance preparation, in-competition fueling, recovery and adaptation, energy availability, physique management, protecting against illness and injury, technological support, the use of supplements and sports foods, and age- and sex-specific considerations. Cycling-specific considerations are used to develop targeted nutritional recommendations within each of these themes, and high-priority future research directions are identified.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-27"},"PeriodicalIF":2.5,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148976884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Menstrual Cycle Phase Is Associated With Changes in Body Weight, Bioimpedance, and Carbohydrate Intake, but Not in Resting Metabolic Rate in Physically Active Females.","authors":"Michaela Wagner, Adam Wagner, Ida Löfberg, Nina Farkašová, Filip Zlámal, Anežka Hurtová, Marta Gimunová","doi":"10.1123/ijsnem.2026-0015","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0015","url":null,"abstract":"<p><p>This observational repeated-measures study investigated the effect of three menstrual cycle phases on resting metabolic rate (RMR), body composition, and dietary intake in 21 naturally menstruating, physically active females (age 24.9 ± 4.1 years; height 168.4 ± 7.8 cm). Measurements were scheduled during the early follicular (EFP), ovulatory, and mid-luteal (MLP) phases using menstrual bleeding onset and urinary luteinizing hormone tests. RMR was measured using indirect calorimetry, body composition via multifrequency bioelectrical impedance analysis, and dietary intake through 3-day food records. Linear mixed-effects models revealed no statistically significant differences in RMR across phases (p = .148). Most dietary intake variables remained stable across the cycle (all p ≥ .074); however, absolute carbohydrate intake was significantly higher in the EFP (234 ± 48 g) than in the MLP (209 ± 53 g; p = .037). Body weight significantly decreased from the EFP (65.2 ± 7.4 kg) to the MLP (64.9 ± 7.3 kg; p = .029). Similarly, the extracellular water ratio decreased (0.376 ± 0.004 vs. 0.374 ± 0.005; p = .019), and phase angle increased (5.85 ± 0.45 vs. 5.98 ± 0.53; p = .021) between the EFP and the MLP. Estimates of fat-free mass and body fat percentage did not differ (p > .05). In physically active females, RMR and most dietary intake variables remained statistically stable across the cycle, whereas carbohydrate intake was higher in EFP than in MLP. Observed fluctuations in body weight and bioimpedance metrics likely reflect hydration shifts rather than changes in tissue composition.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-9"},"PeriodicalIF":2.5,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148929970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fuel Doesn't Fix It: Oculomotor Control Declines During 3 Hr of Exercise Irrespective of Carbohydrate Availability.","authors":"Charlotte J W Connell, Shelley Duncan, Joanna M Black, Gustav Kuhn, Benjamin Thompson, Nicholas Gant","doi":"10.1123/ijsnem.2025-0231","DOIUrl":"https://doi.org/10.1123/ijsnem.2025-0231","url":null,"abstract":"<p><strong>Purpose: </strong>This study investigates whether carbohydrate supplementation during 3 hr of cycling attenuates postexercise changes in oculomotor control and visual performance.</p><p><strong>Methods: </strong>Within a double-blind, randomized, placebo-controlled, repeated-measures, crossover design, nine healthy males completed two 180-min cycling trials at 60% of maximal aerobic capacity, ingesting either a carbohydrate (0.7 g·kg-1·hr-1) or placebo solution. Saccadic eye movements (rapid, ballistic gaze shifts used to redirect the fovea to targets of interest), visual acuity, binocular function, and global motion perception were assessed before and after exercise. Heart rate, perceived exertion, blood glucose, and serum insulin levels were monitored throughout exercise.</p><p><strong>Results: </strong>Blood glucose diverged significantly between conditions across the 180-min exercise protocol, reaching hypoglycemic levels (<4 mmol/L) in placebo from 150 min (placebo: 3.2 ± 0.4 vs. carbohydrate: 5.2 ± 0.7 mmol/L at 180 min). Postexercise saccade velocity, amplitude, and latency changed equivalently across both conditions (-13% velocity, -1° amplitude, +25-ms latency; all p < .01). Visual attention, global motion perception, visual acuity, and binocular function were unchanged by exercise or intervention.</p><p><strong>Conclusion: </strong>Postexercise reductions in saccade velocity and amplitude, and increased latency, were observed regardless of glycemic state, reflecting impaired oculomotor output independent of carbohydrate availability, while visual performance was preserved. These findings point toward a centrally mediated neural mechanism rather than carbohydrate substrate limitation.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-10"},"PeriodicalIF":2.5,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148929966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Guideline-Based Carbohydrate Intake on Training Adaptations, Health, and Sleep in Female Rugby Athletes: An Exploratory Study.","authors":"Rebekka Frazer, Christopher D Askew, Amy-Lee Bowler, Louise M Burke, Dominique Condo, Gregory R Cox, Shona L Halson, Alexander H K Montoye, Fiona Pelly, Jonathon Weakley, Gary Slater","doi":"10.1123/ijsnem.2026-0112","DOIUrl":"https://doi.org/10.1123/ijsnem.2026-0112","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":14334,"journal":{"name":"International journal of sport nutrition and exercise metabolism","volume":" ","pages":"1-16"},"PeriodicalIF":2.5,"publicationDate":"2026-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148897371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}