International journal of sport nutrition and exercise metabolism最新文献

High-amylose maize starch (HAMS), containing fermentable resistant starch (RS), is suggested to improve fluid absorption/retention in athletes but lacks supporting evidence and may increase gastrointestinal symptom (GIS) risk. This study investigated the use of HAMS in pre- and postexercise hydration protocols on hydration status and GIS before, during, and after exertional heat stress (EHS), and thermophysiological strain and exhaustive exercise performance during EHS. Ten endurance-trained runners (eight men and two women) completed two trials in randomized order, consuming a HAMS beverage (12.7 g RS) or placebo 12 hr pre-EHS as part of a 25-ml/kg hyperhydration protocol. Participants then completed 2 hr of steady-state running (60% maximum oxygen uptake, ∼30 °C, 35% relative humidity) followed by a time-to-exhaustion performance test. Post-EHS, participants consumed a HAMS recovery beverage (6.2 g RS) or placebo while replacing 150% of their fluid deficit over 3 hr. HAMS did not influence net fluid balance pre-EHS (HAMS: +44 ± 642 ml, placebo: +210 ± 697 ml) or post-EHS (HAMS: +1,636 ± 687 ml, placebo: +1,662 ± 697 ml; p = .40). Changes in plasma volume and osmolality, and thermophysiological variables, did not differ between trials (all p > .05). Time-to-exhaustion performance test was unaffected by the intervention (HAMS: 1,190 ± 508 s, placebo: 1,343 ± 631 s; p = .10). GIS incidence and severity scores were similar in both trials (all p > .05). A beverage containing RS from HAMS 12 hr before EHS, or immediately following EHS, does not alter retention of water volumes recommended for preexercise hyperhydration or postexercise rehydration nor GIS pre-, during, or post-EHS. As a result, no changes in hydration status, thermophysiological strain, or performance were observed.

Mouth rinsing with carbohydrates or salt solutions has been shown to attenuate the reduction in maximum voluntary contraction (MVC) strength during fatigue. Although central mechanisms, such as changes in voluntary activation (VA) and motor evoked potentials (MEP), have been proposed to explain this effect, direct evidence is limited. This study aimed to investigate the effects of carbohydrate or salt mouth rinses on central fatigue by examining whether central measures are affected. In a double-blind, randomized, crossover design, 19 male participants completed three experimental trials (carbohydrate, salt, or placebo mouth rinses), each involving a sustained knee isometric fatiguing protocol performed until volitional fatigue. MVC, VA, and MEP were assessed before and after the fatiguing protocol. Following the protocol, the torque output (MVC) and central measures (VA and MEP) showed significant reductions (p < .05). Although the reductions following carbohydrate and salt were less pronounced (MVC, VA, and MEP), both treatments showed better preservation than placebo (p < .001). In addition, the comparable reduction in resting twitch and maintenance of maximum compound muscle action potential (p > .05) suggest that the observed benefits were primarily central mediated. This is the first study to demonstrate that salt mouth rinsing is as effective as carbohydrate rinsing in attenuating neuromuscular fatigue via central mechanisms, preserving muscle activity, central drive, and corticospinal responsiveness following a localized fatiguing protocol.

Objective: To synthesize current evidence on sexual dimorphism in maximal fat oxidation (MFO) and its corresponding exercise intensity (FATmax), exploring key moderators influencing these parameters across populations.

Methods: We conducted a systematic review and meta-analysis, registered in PROSPERO (CRD42024563620), following Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. PubMed, Scopus, and EBSCOhost databases were searched from January 2001 to April 2024 for English- and Spanish-language studies examining MFO and FATmax during graded exercise tests. Studies were included if they reported sex-specific MFO and/or FATmax values derived from indirect calorimetry. Both cross-sectional and longitudinal designs were considered. Exclusion criteria included pooled-sex data, inaccessible full texts, and nonexercise-based MFO assessments.

Results: Thirty-six studies (n = 8,990; 5,133 females, 3,857 males) were included. Absolute MFO was significantly lower in females (MD: -0.06 g/min), but no significant differences were observed in relative MFO (standardized mean difference: 0.202, p = .096) or FATmax (mean difference: 1.29% VO2max, p = .254). Cardiorespiratory fitness, body mass index, and exercise modality were key moderators in both sexes. Treadmill exercise was associated with higher MFO, irrespective of sex. Notably, body mass index and age influenced sexual dimorphism in fat oxidation, with age showing a curvilinear (quadratic) relationship with FATmax, suggesting complex age-related adaptations (p = .008).

Conclusions: This review questions the assumption that women consistently oxidize more fat than men during exercise. The influence of sex on fat metabolism appears context-dependent, emphasizing the need for individualized interpretation. Longitudinal studies are required to evaluate whether these differences confer cardiometabolic protection.

Novel cycling disciplines, such as cycling Esports and gravel racing, have recently seen a surge in participation, media visibility, and the establishment of international competitions. However, there is limited peer-reviewed research into the specific physiological and nutritional demands required for success in these disciplines. As part of the larger UCI Sports Nutrition project, this review utilizes qualitative interviews to gain a deeper understanding of the nutrition practices of athletes currently competing in these events. We contextualize these responses by describing contemporary nutrition strategies and evidence-based practice adopted from other disciplines, along with practical application considering the distinct challenges presented by these new and emerging cycling disciplines. Key issues for these disciplines include in race nutrition targeting the specific needs of the event, noting that the logistics of consuming food and drinks in gravel racing and Esports are different to other modalities such as road cycling. Optimization of body mass is a shared concern particularly in Esports in which the requirement for a prerace "weigh-in" may lead to practices usually seen in weight division sports. Finally, a number of supplements including caffeine, creatine, buffering agents, and hyperhydrating agents such as glycerol may enhance performance when used according to evidence-based protocols.

The effects of Greek yogurt and whey protein supplementation on markers of bone turnover and inflammation were compared in university athletes over a competitive season. Participants (n = 32, 16 females) followed their habitual diets for an 8-week control period and were then randomly assigned to one of two trial arms: two servings per day of either 175 g of Greek yogurt (17 g protein) or isonitrogenous whey protein for a 16-week intervention period. Morning, fasting blood was collected at Weeks 0 (precontrol), 8 (postcontrol/preintervention), 16 (midintervention), and 24 (postintervention) and analyzed for osteocalcin, amino-terminal propeptide of Type I collagen, insulin-like growth factor 1, osteoprotegerin, C-telopeptides of Type I collagen, sclerostin, receptor activator of nuclear factor kappa-B ligand, tumor necrosis factor-alpha, interleukin 6, and interleukin 10. No main effects or interactions were found for markers of bone formation. In the Greek yogurt group, C-telopeptides of Type I collagen increased from pre- to postcontrol and returned to baseline concentrations postintervention while remaining stable throughout the study in whey protein (Time × Group interaction, p = .048). Receptor activator of nuclear factor kappa-B ligand increased from pre- to postcontrol (time effect, p = .014), returning to baseline by midintervention across groups. Males had higher sclerostin (sex effect, p = .021) and interleukin 10 (sex effect, p = .004) with no interactions. Interleukin 6 showed no main effects or interactions. Tumor necrosis factor-alpha increased pre- to postcontrol (time effect, p = .053) then decreased to baseline levels postintervention. Although protein supplementation, independent of source (wholefood or isolates), showed potential bone and inflammatory benefits during athletic training, it remains unclear whether these effects were solely attributable to the supplements.

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.

Elite cyclists frequently train and compete in extreme environments, such as heat, and cold conditions that are becoming more common due to climate change. Altitude training, aimed at preparing athletes for high-altitude events, is widely employed to enhance subsequent sea-level performance. Similarly, heat training has proven to have a similar transfer effect, in addition to the essential acclimatization effects, relevant for performance in hot conditions. Exposure to these challenging environments increases physiological stress raising energy and carbohydrate oxidation rates, and affecting overall performance. This Union Cycliste Internationale (UCI) consensus on nutrition for cycling addresses the nutritional challenges associated with extreme environmental conditions and explores tailored nutrition and hydration strategies to mitigate their effects. The review examines how heat, cold, and altitude affect hydration, energy expenditure, and metabolism, with associated macro- and micronutrient considerations, in cyclists. It discusses practical strategies for managing fluid balance, carbohydrate intake, and micronutrient and electrolyte supplementation and the use of ergogenic aids in supporting adaptation to environmental stresses. This review provides evidence-based nutrition and fluid recommendations for optimizing cycling performance and fostering adaptation in extreme environments. It offers practical guidance on nutrition and hydration strategies before, during, and after training and competition, helping cyclists maintain peak performance while navigating the unique challenges posed by these conditions.