Journal of the International Society of Sports Nutrition最新文献

{"title":"Day-to-day variability in resting metabolic rate in strength athletes.","authors":"Claire Buechel, Kate Pumpa, Naroa Etxebarria, Luke Ashton, Michelle Minehan","doi":"10.1080/15502783.2026.2704927","DOIUrl":"10.1080/15502783.2026.2704927","url":null,"abstract":"<p><strong>Background: </strong>Resting Metabolic Rate (RMR) is measured in sport settings for health monitoring and nutrition planning; however, interpreting repeated measures requires an understanding of typical day-to-day variability under habitual, free-living conditions. This study quantified intra-individual variability in RMR among weight-stable strength-trained athletes, examined the impact of data processing approaches, and established protocol-specific least significant change (LSC) thresholds under ecological conditions.</p><p><strong>Methods: </strong>A repeated-measures design was used to quantify intra-individual variability in RMR in 13 weight-stable strength-trained athletes (8 male, 5 female). RMR was measured on five consecutive mornings using the Parvo Medics TrueOne 2400 metabolic cart with a Hans Rudolph mouthpiece under standardized conditions. Breath-by-breath data were processed using multiple cleaning approaches to evaluate their impact on RMR estimates, with the most reliable method retained for analysis. Intra-individual variability was quantified and used to derive protocol-specific LSC thresholds.</p><p><strong>Results: </strong>Session averaging produced the lowest intra-individual variability in RMR (CV: 3.4 ± 1.4%) compared with alternative data cleaning approaches. Mean RMR was 26.9 ± 1.4 and 29.1 ± 1.7 kcal·kgFFM^-1·day^-1 in males and females, respectively. The group-level LSC was 2.9 ± 1.2 kcal·kgFFM^-1·day^-1 (10.4 ± 4.2%), representing the magnitude of change required to exceed expected within-subject variability under the conditions of this protocol. Fat-free mass (FFM) was positively associated with both absolute RMR and day-to-day variability, whereas prior-day training load and protein intake showed no clear association with RMR variability.</p><p><strong>Conclusions: </strong>Notable intra-individual variability occurs in repeated RMR measurements in strength-trained athletes under applied conditions. Meaningful interpretation of change requires protocol-specific reliability estimates to distinguish true physiological change from expected day-to-day variation. Session averaging improves measurement consistency and is recommended for mouthpiece-based indirect calorimetry systems. RMR should be interpreted relative to individual and context-specific variability rather than universal thresholds.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2704927"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13386584/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148497748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An extract from whole <i>Coffea arabica</i> coffee cherry improves time trial performance, but not muscle glycogen resynthesis, in trained cyclists.","authors":"George F Pavis, Ronald L Kingma, Boris V Nemzer, Nebiyu Abshiru, Benjamin T Wall, Francis B Stephens","doi":"10.1080/15502783.2026.2682323","DOIUrl":"10.1080/15502783.2026.2682323","url":null,"abstract":"<p><strong>Background: </strong>This study aimed to test the hypothesis that a whole <i>Coffea arabica</i> coffee cherry extract concentrated in caffeine and polyphenols would increase exercise performance and muscle glycogen resynthesis.</p><p><strong>Methods: </strong>Twelve trained cyclists (11 male, 1 female; V̇O_2max: 55 ± 2 mL·kg^-1·min^-1) took part in a double blind, randomized, placebo-controlled, cross-over trial. Participants consumed either a coffee cherry extract supplement containing 200 mg caffeine and 15 mg polyphenols (CB) or placebo (PLA), before exercising for 30 min on a cycle ergometer at 79 ± 1% V̇O_2max followed by a 15 min time trial (TT1). A second supplement was then consumed with 1 g·kg bm^-1 carbohydrate and a second time trial (TT2) was performed the following morning. Blood samples were collected throughout, and muscle biopsies were collected immediately after TT1 (0 h), and at 4 and 24 h.</p><p><strong>Results: </strong>Plasma caffeine and chlorogenic acid concentrations increased during exercise and subsequent recovery in CB compared to PLA (<i>p</i> < 0.001). Total work performed during TT1 was 4.6% ± 1.5% greater with CB than PLA (3.14 ± 0.15 vs. 3.02 ± 0.17 kJ·kg^-1; Hedge's g [95% confidence interval] = 0.8 [0.2, 1.4]; <i>p</i> < 0.05). Perceived exertion was lower during steady-state exercise with CB (<i>p</i> < 0.05); respiratory exchange ratio did not differ. From 0 to 4 h recovery, muscle glycogen content increased similarly in PLA and CB by 64 ± 13 and 44 ± 10 mmol·kg dw^-1, respectively, and by 53 ± 8 and 45 ± 10 mmol·kg dw^-1 from 4 to 24 h (<i>P</i> < 0.001).</p><p><strong>Conclusions: </strong>We report that an extract from whole <i>Coffea arabica</i> cherry containing a low dose of caffeine and polyphenols is ergogenic but was not shown to enhance muscle glycogen resynthesis following post-exercise consumption of 1 g·kg bm^-1 carbohydrate. <b>Clinical trials registration:</b> Registered with clinicaltrials.gov on 10/01/2022 as NCT05404841 (URL: https://clinicaltrials.gov/study/NCT05404841).</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2682323"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13235231/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148156888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selected immunoendocrine and performance adaptations to upper-body plyometric training and β-alanine supplementation in male swimmers.","authors":"Hui Gao, Xuemei Yu, Zhiyong Guo","doi":"10.1080/15502783.2026.2679050","DOIUrl":"10.1080/15502783.2026.2679050","url":null,"abstract":"<p><strong>Background: </strong>Upper-body plyometric training (PT) enhances neuromuscular performance and power production. However, its application in swimming and its potential interaction with β-alanine (BA) supplementation remain largely unexplored. Therefore, this study investigated the combined effects of upper-body PT and BA supplementation on performance and immunoendocrine adaptations in trained male swimmers.</p><p><strong>Methods: </strong>Thirty trained male swimmers (age: 25.7 ± 2.6 years; height: 1.83 ± 0.07 m; body mass: 81.6 ± 3.2 kg) were randomly assigned to one of three groups: PT + BA, PT + placebo (PL), or control (CON). Participants in the PT groups completed an 8-week upper-body PT program (2 sessions·week⁻¹). Each session consisted of upper-body plyometric exercises performed for 3-4 sets of 12-16 repetitions with 120 s rest between sets. Participants in the supplementation groups ingested β-alanine (4.8 g·day⁻¹ divided into six 0.8 g doses) or a matched placebo daily throughout the intervention. Assessments conducted before and after the intervention included medicine ball throw (MBT), push-up endurance, one-repetition maximum (1RM) bench press, swim ergometer peak and mean power output (PPO and MPO), and 50-, 100-, and 200-m freestyle performance. Blood samples were also collected pre- and post-intervention to determine testosterone, cortisol, and immunoglobulin A (IgA) concentrations.</p><p><strong>Results: </strong>Both PT groups showed significant improvements in all performance outcomes compared with baseline (all p < 0.05), with effect sizes ranging from small to moderate. Post hoc analyses revealed a significant group × time interaction for MBT (p = 0.045), push-up endurance (p = 0.041), PPO (p = 0.026), and MPO (p = 0.033), indicating greater improvements in the PT + BA group than in the PT + PL group. In addition, following the training intervention, the PT + BA group showed significant changes in testosterone (p = 0.011), cortisol (p = 0.028), and IgA (p = 0.042) concentrations compared with the PT + PL group.</p><p><strong>Conclusions: </strong>Eight weeks of upper-body PT significantly enhanced upper-body power, anaerobic capacity, and swimming performance in trained male swimmers. BA supplementation further amplified these training-induced adaptations and promoted a more favorable immunoendocrine adaptation profile. These findings suggest that combining upper-body PT with β-alanine supplementation may provide synergistic benefits for performance development and physiological recovery in competitive swimmers.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2679050"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13224686/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148138080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The interplay between vitamin D status and exerkine signaling: implications for exercise adaptation in athletes: narrative review.","authors":"Do-Houn Kim","doi":"10.1080/15502783.2026.2677647","DOIUrl":"10.1080/15502783.2026.2677647","url":null,"abstract":"<p><strong>Background: </strong>Exercise elicits systemic adaptations through a coordinated network of exercise-responsive signaling molecules termed exerkines. Vitamin D, classically linked to calcium homeostasis, has been increasingly characterized as a pleiotropic hormone with immunomodulatory and myotropic actions that may be relevant to training adaptation and recovery in athletic populations.</p><p><strong>Objective: </strong>This narrative review synthesizes mechanistic and clinical evidence examining whether vitamin D status and supplementation are associated with modulation of selected exercise-responsive exerkines, and it introduces a unifying conceptual model, the \"vitamin D-exerkine axis\", to frame potential points of interaction between vitamin D signaling and the exercise-induced secretome.</p><p><strong>Methods: </strong>A narrative literature review was conducted using searches of PubMed and Google Scholar, incorporating mechanistic, observational, and intervention studies in animal and human models relevant to vitamin D signaling and exercise-responsive exerkines. Evidence was synthesized qualitatively to distinguish biological plausibility from athlete-specific causal inference.</p><p><strong>Results: </strong>Across experimental systems, vitamin D signaling via the vitamin D receptor (VDR) has been associated with expression of several exerkines implicated in inflammation, metabolism, and muscle remodeling. Evidence most consistently discussed in the literature involves IL-6, irisin/FNDC5, myostatin, and anti-inflammatory cytokines (e.g. IL-10), although effect direction and magnitude appear context-dependent and are influenced by baseline vitamin D status, study design, and outcome timing. A bidirectional relationship is plausible: exercise may upregulate VDR expression in skeletal muscle and has been associated with transient changes in circulating vitamin D metabolites, while vitamin D sufficiency may shape aspects of the post-exercise inflammatory and metabolic milieu. Collectively, these observations support a working model in which vitamin D status could modulate parts of the exercise-response signaling network, but definitive athlete-focused causal evidence remains limited.</p><p><strong>Conclusion: </strong>The proposed vitamin D-exerkine axis offers a hypothesis-generating conceptual model for integrating nutrition endocrinology with exercise physiology. Current data support biological plausibility for interaction, yet heterogeneity in study populations, endpoints, and supplementation protocols constrains strong causal inference in athletes. Future research should prioritize well-controlled trials that account for baseline 25(OH)D status, define dose-response relationships, test sex- and sport-specific effects, and incorporate tissue-level endpoints to clarify mechanisms and relevance to training adaptation and recovery.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2677647"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13202679/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148005739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of (poly)phenol-rich sugarcane extract intervention on markers of gastrointestinal integrity and systemic inflammation in response to exertional-heat stress.","authors":"Ulluwis H A J Hewawansa, Kayla Henningsen, Natália Vilela Silva Daniel, Sandra In, Giles Sugay, Michael J Houghton, Elizabeth Barber, Gary Williamson, Ricardo J S Costa","doi":"10.1080/15502783.2026.2684574","DOIUrl":"10.1080/15502783.2026.2684574","url":null,"abstract":"<p><strong>Background: </strong>Exertional-heat stress (EHS) perturbs gastrointestinal integrity, leading to systemic inflammation that may warrant medical attention. The study aimed to determine the effects of a (poly)phenol-rich sugarcane extract (PRSE) beverage and gel interventions on biomarkers of intestinal epithelial integrity and systemic immune responses to an EHS challenge.</p><p><strong>Method: </strong>Using a double-blind placebo-controlled design, participants (<i>n</i> = 14) were randomly allocated to complete two EHS (i.e. 2 h running at 60% <math><mover><mi>V</mi><mo>˙</mo></mover><msub><mi>O</mi><mrow><mn>2</mn><mi>max</mi></mrow></msub></math> in 34.4 °C ambient temperature) trials, with at least one-week washout. Participants consumed 2 × 270 mL beverages daily for 14 days before EHS, and 1 × 270 mL beverage pre-EHS and a gel sachet every 20 min during EHS. Beverages and gels were either PRSE (beverage: 10% w/v, gel: 46% w/v) or carbohydrate-matched placebo. Whole blood samples were collected pre-EHS, immediately post-EHS and 30 min, 1 h, and 2 h post-EHS, and analyzed for plasma concentrations of cortisol, I-FABP, sCD14, and systemic inflammatory cytokines.</p><p><strong>Results: </strong>Compared with placebo, the PRSE trial exhibited higher rectal temperature (<i>p</i> = 0.046) and physiological strain index (<i>p</i> = 0.010). No Trial × Time interaction was observed for I-FABP; however, pre-EHS plasma I-FABP concentration was lower in PRSE compared to placebo. Plasma IL-8 concentration increased over time (<i>p</i> < 0.001) that was attenuated by PRSE compared with placebo (<i>p</i> = 0.023). Exercise-associated gastrointestinal symptoms (Ex-GIS) incidence was high in both trials, while average symptom severity was lower with PRSE.</p><p><strong>Conclusion: </strong>Two weeks of PRSE supplementation with a carbohydrate-containing beverage during EHS may provide modest advantages to intestinal epithelial integrity and systemic inflammatory, without further exacerbating Ex-GIS.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2684574"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13288546/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148277893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HMB supplementation combined with high-intensity functional exercise supports aerobic capacity but not strength in trained and untrained males: a randomized controlled trial.","authors":"Krzysztof Durkalec-Michalski, Michał Murawa, Michal Steffl, Tomasz Podgórski, Jakub Adamczewski, Małgorzata Marchelek-Myśliwiec, Tereza Jandova, Michal Vagner, Paulina M Nowaczyk","doi":"10.1080/15502783.2026.2695124","DOIUrl":"10.1080/15502783.2026.2695124","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;&lt;i&gt;β&lt;/i&gt;-hydroxy-&lt;i&gt;β&lt;/i&gt;-methylbutyrate (HMB) supplementation may support aerobic capacity and isometric strength. Its utility has been studied mainly for 3 g &lt;sub&gt;HMB&lt;/sub&gt;·day&lt;sup&gt;-1&lt;/sup&gt;. Therefore, new and personalized HMB supplementation protocols should be verified. This parallel randomized placebo(PLA)-controlled triple-blind study was designed to evaluate the effects of liquid HMB free acid supplementation during customary training/lifestyle or combined with high-intensity functional training (HIFT) on aerobic fitness, physical capacity, and isometric strength indices following an incremental cycling test (ICT) in trained (TR) and untrained (UTR) males.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Fifty-three TR (29.1 ± 7.7 years; body mass (BM): 84.8 ± 10.0 kg; FFM: 71.2 ± 8.9 kg) and 37 UTR participants (32.3 ± 7.6 years; BM: 90.1 ± 16.5 kg; FFM: 68.4 ± 10.3 kg) completed two 3-weeks periods, including: &lt;i&gt;1)&lt;/i&gt; supplementation period (&lt;i&gt;SUP&lt;/i&gt;)-ingesting 90 mg·kg&lt;sub&gt;FFM&lt;/sub&gt; &lt;sup&gt;-1&lt;/sup&gt;·day&lt;sup&gt;-1&lt;/sup&gt; of either HMB or PLA and performing usual training (TR) or lifestyle (UTR), and &lt;i&gt;2)&lt;/i&gt; HMB/PLA ingestion combined with the additional HIFT stimuli (2 units per week; &lt;i&gt;SUP + EX&lt;/i&gt;). &lt;i&gt;TR_HMB&lt;/i&gt;, &lt;i&gt;TR_PLA&lt;/i&gt;, &lt;i&gt;UTR_HMB&lt;/i&gt;, &lt;i&gt;UTR_PLA&lt;/i&gt; groups were analyzed. Testing visits were performed at baseline (&lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;BAS&lt;/i&gt;&lt;/sub&gt; ), and after the &lt;i&gt;SUP&lt;/i&gt; (&lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP&lt;/i&gt;&lt;/sub&gt; ) and the &lt;i&gt;SUP + EX&lt;/i&gt; (&lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP+EX&lt;/i&gt;&lt;/sub&gt; ). The following evaluations were performed: BM and body composition, ICT, and maximal voluntary isometric contraction (MVIC) of the lower limb. A general linear model was conducted to examine the main effects and interaction of &lt;i&gt;treatment&lt;/i&gt; (supplementation) (HMB/PLA), &lt;i&gt;training status&lt;/i&gt; (TS; TR/UTR), and &lt;i&gt;baseline values&lt;/i&gt; (&lt;i&gt;BAS&lt;/i&gt;) over repeated measurements (&lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;BAS&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;, T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP&lt;/i&gt;&lt;/sub&gt; , &lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP+EX&lt;/i&gt;&lt;/sub&gt; ). The following interactions were tested: &lt;i&gt;visit × treatment&lt;/i&gt;; &lt;i&gt;visit × TS&lt;/i&gt;; &lt;i&gt;visit × treatment × TS; and visit × treatment × TS × BAS&lt;/i&gt;. One-way ANOVA or Kruskal-Wallis ANOVA (non-normal distribution) were conducted to examine differences in the degree of absolute changes (&lt;i&gt;ΔT&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;-T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;BAS&lt;/i&gt;&lt;/sub&gt; , &lt;i&gt;ΔT&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP+EX&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;-T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP&lt;/i&gt;&lt;/sub&gt; , &lt;i&gt;ΔT&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP+EX&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;-T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;BAS&lt;/i&gt;&lt;/sub&gt; ) in the measured indices between studied subgroups.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Increases (&lt;i&gt;T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;SUP+EX&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;-T&lt;/i&gt; &lt;sub&gt;&lt;i&gt;BAS&lt;/i&gt;&lt;/sub&gt; ) in VO&lt;sub&gt;2MAX&lt;/sub&gt; (&lt;i&gt;p&lt;/i&gt; = 0.024), time to the anaerobic threshold (AT; &lt;i&gt;p&lt;/i&gt; &lt; 0.001), VO&lt;sub&gt;2AT&lt;/sub&gt; (&lt;i&gt;p&lt;/i&gt; = 0.001), power output at the AT (&lt;i&gt;p&lt;/i&gt; &lt; 0.001), heart rate at the AT (&lt;i&gt;p&lt;/i&gt; &lt; 0.001), time to the respiratory compensation point (RCP; &lt;i&gt;p&lt;/i&gt; &lt; 0.001), VO&lt;sub&gt;2RCP&lt;/sub&gt; (&lt;i&gt;p&lt;/i&gt; &lt; 0.001), power output at t","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2695124"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13366636/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148437087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Creatine formulations and repeated sprint training: effects on physical and physiological adaptations in soccer players during the short-term preparation phase.","authors":"Changyuan Duan, Zaitao Wang, Qianjin Wang","doi":"10.1080/15502783.2026.2721147","DOIUrl":"10.1080/15502783.2026.2721147","url":null,"abstract":"<p><strong>Background: </strong>This research examined the impact of various creatine (Cr) supplementation formulations during a 4-week preparatory phase on the efficacy of repeated sprint training (RST) and on improvements in physical and physiological performance in male soccer athletes.</p><p><strong>Methods: </strong>A total of forty collegiate young soccer players volunteered for the study. They were randomly divided into four groups: creatine monohydrate (Cr-Mon, <i>n</i> = 10), creatine ethyl ester (Cr-Ee, <i>n</i> = 10), creatine hydrochloride (Cr-Hcl, <i>n</i> = 10), and placebo (PL, <i>n</i> = 10). All athletes engaged in a 4-week training intervention, three times a week (i.e. 12 sessions), and physical (countermovement vertical jump [CMVJ], 20-m sprint, and L-run) and physiological (Wingate anaerobic power and incremental exercise tests) performance were assessed both before and after the training period.</p><p><strong>Results: </strong>All training groups improved physical and physiological performance following the 4-week intervention period (<i>p</i> < 0.05). Additionally, the groups receiving the Cr supplement exhibited significantly greater changes (<i>p</i> = 0.001) in physical performance, peak power output, and fatigue index compared to the PL group. However, no significant differences were found among the groups regarding mean power output and VO2max. Notably, the Ee and Hcl forms of Cr showed superior gains (<i>p</i> < 0.05) in physical performance and peak power compared to the Mon form after the 4-week intervention.</p><p><strong>Conclusions: </strong>The results underscore the importance of Cr ingestion in enhancing adaptations for short-term physical performance tasks, highlighting the effectiveness of the Ee and Hcl forms in further improving the CMVJ, 20-m sprint, L-run, and peak power among soccer players during the short-term preparation phase.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 sup1","pages":"2721147"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13564169/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148919930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"International Society of Sports Nutrition position stand: effects of dietary antioxidants on exercise and sports performance.","authors":"Drew E Gonzalez, Broderick L Dickerson, Brandon M Roberts, Jennifer A Kurtz, Hunter S Waldman, Adam M Gonzalez, Matthew J McAllister, Jeffery L Heileson, Richard J Bloomer, Shawn M Arent, Darren G Candow, Jeffrey R Stout, Karen A Hecht, Bill Campbell, Chad M Kerksick, Douglas Kalman, Jose Antonio, Richard B Kreider","doi":"10.1080/15502783.2026.2629828","DOIUrl":"10.1080/15502783.2026.2629828","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Following a comprehensive review, the International Society of Sports Nutrition (ISSN) has developed an official position on the role of dietary antioxidants in exercise and sport. Antioxidants play a complex, context-dependent role in vivo; they can facilitate recovery from exercise but may also hinder training adaptations when consumed at supraphysiological doses. While endogenous antioxidant systems can effectively maintain redox balance, dietary sources, particularly whole foods, can help mitigate excessive oxidative stress following intense/heavy training or inadequate recovery. The influence of dietary antioxidants depend on timing, dosage, type, and individual factors. The ISSN's official position encompasses the following: (1) Redox balance exists on a spectrum, with mild oxidative eustress driving beneficial physiological adaptations and excessive oxidative distress impairing health, recovery, and performance; (2) Moderate levels of exercise-induced reactive oxygen and nitrogen species (ROS/RNS) can support training adaptations but excessive levels can result in muscle damage, inflammation, and reduced physical performance and immune function; (3) Endogenous and exogenous antioxidants protect cells by neutralizing free radicals and reducing oxidative damage to biomolecules; (4) FDA labeling for \"antioxidant\" claims applies to nutrients with established RDIs and demonstrated antioxidant activity; this typically includes vitamins C and E, β-carotene (a source of vitamin A), selenium, zinc, copper, and manganese; (5) While dietary antioxidants show potential for both direct and indirect effects, the evidence varies, and their use should be tailored to individual performance or recovery goals; (6) Long-term exercise augments endogenous antioxidant defense and should be the primary strategy for enhancing redox capacity before considering supplementation; (7) Whole foods and beverages rich in flavonoids, polyphenols, carotenoids, vitamins, and minerals are preferred antioxidant sources; (8) Dietary supplementation is best reserved for nutrient insufficiencies or deficiencies, inadequate dietary intake, or periods of high training distress; (9) Responses to supplementation vary by individual factors, such as training status, baseline antioxidant capacity, demographics, diet, and injury risk, with some antioxidant compounds offering cognitive, behavioral, or physical-related benefits; and (10) Creatine monohydrate (i.e. 0.1 g/kg/day), omega-3 fatty acids (1000-6000 mg/day EPA+DHA for 6-12 weeks), tart cherry (480 mg powder or 60-90 mL juice/day for 7-14 days), and astaxanthin (4-12 mg/day for 4-12 weeks) rank among the top nutrients for their antioxidant effects, with moderate- to high-quality evidence supporting their use in recovery or performance without interfering with training adaptations. Most others show weak or low efficacy. This position promotes an individualized, evidence-based approach, recognizing that small to moderate exerc","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2629828"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12915426/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146213576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bifidobacterium longum BB536 is associated with improvements in gastrointestinal symptoms and odor-related metabolites in microbiota-defined subgroups of male athletes consuming a high-protein diet: exploratory randomized double‑blind placebo‑controlled trial.","authors":"Shu Miyamoto, Shin Yoshimoto, Noriko Katsumata, Natsumi Mutoh, Noriyuki Iwabuchi, Toshitaka Odamaki, Daisuke Asaoka, Shuichi Machida","doi":"10.1080/15502783.2026.2664664","DOIUrl":"10.1080/15502783.2026.2664664","url":null,"abstract":"<p><strong>Background: </strong>High‑protein diets are widely used by athletes but may disturb the gut environment and increase production of odor‑related metabolites. Probiotic supplementation has been proposed as a strategy to support gastrointestinal function under such dietary stress. This study aimed to explore the effects of <i>Bifidobacterium longum</i> BB536 on gastrointestinal symptoms, gut microbiota, and odor‑related metabolites in male athletes consuming a high‑protein diet.</p><p><strong>Methods: </strong>In an exploratory, randomized, double‑blind, placebo‑controlled trial, 60 healthy male athletes (mean age: 18.62 ± 0.75 years; mean BMI: 22.35 ± 1.80 kg/m²) consumed a whey protein supplement (70 g/day) together with either BB536 (46 billion CFU/day, as measured at the start of the intervention) or placebo for 4 weeks. Gastrointestinal symptoms, gut microbiota composition, skin‑emitted volatile compounds, and fecal metabolites were assessed. Subgroup analyses based on responder status and baseline enterotype were conducted post hoc to generate hypotheses regarding microbiota‑dependent responses.</p><p><strong>Results: </strong>In the overall cohort, no significant between‑group differences were observed across gastrointestinal outcomes, gut microbiota indices, or metabolite profiles. Within the BB536 group, diarrhea‑related scores improved from baseline. Post hoc analyses suggested that increases in <i>Faecalibacterium</i> were evident among responders. Enterotype‑based patterns also emerged: individuals with <i>Ruminococcus</i>‑dominant microbiota showed higher skin‑emitted short‑chain fatty acids after BB536 intake, whereas those with <i>Faecalibacterium</i>‑dominant microbiota exhibited reductions in odor‑related metabolites, including methyl mercaptan and ammonia. Corresponding fecal metabolite shifts were modest.</p><p><strong>Conclusion: </strong>BB536 supplementation was associated with improvements in diarrhea‑related symptoms and odor‑related metabolites in specific microbiota‑defined subgroups. As these findings did not extend to the full cohort, they should be interpreted as exploratory and hypothesis‑generating. Baseline gut microbiota composition may influence probiotic responsiveness, warranting confirmatory trials with prespecified endpoints.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2664664"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13126944/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147775355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Caffeine makes a splash: a systematic review and multilevel meta-analysis exploring the effects of caffeine intake on swimming performance.","authors":"Ziyu Wang, Bopeng Qiu, Jinxuan Bao, Penglin Diao, Michael Hamlin, Juan Del Coso, Jozo Grgic, Carl Petersen","doi":"10.1080/15502783.2026.2692016","DOIUrl":"10.1080/15502783.2026.2692016","url":null,"abstract":"<p><strong>Background: </strong>Evidence for acute caffeine supplementation in swimming remains inconsistent across reviews, likely due to between-study heterogeneity and methodological differences.</p><p><strong>Methods: </strong>Five databases were searched for randomized placebo-controlled crossover trials exploring the effects of caffeine on swimming performance in competitive swimmers. Performance outcomes were pooled as standardized mean differences (SMD; Hedges' g), with time outcomes sign-reversed so that positive values indicated improved performance. Dependence among multiple outcomes within studies was addressed using three-level random-effects models (REML). As a supplementary, interpretable metric, log ratios of means (lnRoM) were meta-analysed and expressed as percentage change. Post-exercise blood lactate (mmol/L) was pooled as mean differences (MD). Risk of bias was assessed using RoB 2 and certainty of evidence using GRADE. Prespecified exploratory moderator analyses examined potential effect modification (dose, timing, distance, administration form, stroke, gender, and athlete level).</p><p><strong>Results: </strong>Thirteen studies were included (144 men and 48 women), which contributed 28 performance effect sizes. Caffeine improved swimming performance (SMD = 0.57, 95% CI: 0.20 to 0.94; <i>p</i> = 0.005), corresponding to a +1.71% improvement in lnRoM (95% CI: +1.01% to +2.41%; <i>p</i> < 0.001). Heterogeneity was substantial (I²_total = 64.7%) and primarily between studies. Eight studies contributed 24 blood lactate effect sizes. In the meta-analysis, caffeine increased post-test lactate (MD = 0.85 mmol/L, 95% CI: 0.22 to 1.49; <i>p</i> = 0.016) with high heterogeneity (I²_total = 76.5%). Exploratory moderator analyses suggested a possible dose-related pattern for swimming performance, with larger pooled effects at ≥6 mg/kg (SMD = 0.95, 95% CI: 0.52 to 1.38) than at <6 mg/kg (SMD = 0.22, 95% CI: -0.15 to 0.60; <i>p</i> _difference = 0.017). Other performance moderators did not show clear between-subgroup differences. For lactate, exploratory subgroup analyses suggested larger increases in freestyle and short-distance events, although these patterns were more sensitive to modelling assumptions and should be interpreted cautiously.</p><p><strong>Conclusion: </strong>Acute caffeine ingestion confers a moderate ergogenic benefit for swimming performance (SMD = 0.57, 1.7% improvement) and is associated with higher post-test blood lactate (MD = 0.85 mmol/L). Dose (≥6 mg/kg) may be associated with larger performance benefits, whereas lactate responses appear more pronounced in freestyle and shorter events. However, these subgroup findings are hypothesis-generating and require exploration.</p>","PeriodicalId":17400,"journal":{"name":"Journal of the International Society of Sports Nutrition","volume":"23 1","pages":"2692016"},"PeriodicalIF":4.9,"publicationDate":"2026-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13288720/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148295510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}