International journal of sport nutrition and exercise metabolism最新文献

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.

As a group, cyclists tend to have lower bone mass compared with other athletes, and nonathlete controls which may have negative consequences for fracture risk and longer term bone health. There are several cycling-specific factors that may contribute to this finding. These include, the low-impact, repetitive load nature of cycling which provides limited stimulus for bone metabolism; metabolic perturbations that occur following prolonged cycling that may lead to a transient increase in the rate of bone resorption; and nutritional factors, including low energy availability or nutrient inadequacy. Furthermore, many endurance cyclists are naturally lean and light, which may result from both genetic predisposition and long-term training adaptations. In turn, they may also have lower bone mass. None of these factors stand out as the primary cause of the low bone mass reported in cyclists but, instead, may combine to create a "perfect storm" to challenge cyclist bone health. Given these multiple potential challenges to bone health, a multifaceted approach may be required to combat them. On an individual level, nutritional strategies, including ensuring adequate energy, carbohydrate, protein, calcium, vitamin D, and other important micronutrients may be key to protecting cyclist bone health. Integrating brief bouts of high-impact loading within the training regimen and ensuring adequate sleep and recovery are also recommended. The onus should not remain solely on the individual, however, and cycling teams and organizational bodies have a key role to play in providing screening and educational strategies to support cyclists bone health.

Nutritional supplement use is common among athletes aiming to enhance performance, recovery, and health. However, variable regulatory frameworks and limited safety oversight create risks for inadvertent doping violations. This article provides a global overview of supplement use, relevant authorities, legislation, and safety measures, with a focus on third-party testing (TPT) as a risk-mitigation strategy. Data from six global regions-Africa, Asia, Australia/New Zealand, Europe, Latin America, and North America-were synthesized from peer-reviewed studies, governmental sources, and regional expert contributions. Reported supplement use ranged from 7% to 100% among athletes (variability within regions), with protein powders, vitamins/minerals, creatine, caffeine, and sports drinks being most prevalent. High-risk products (potential anti-doping rule violations), including certain herbal blends, preworkouts, and weight-management supplements, were reported across all regions. While some countries have robust regulatory systems, most lack harmonized or enforceable safety frameworks. TPT programs, which independently verify products for prohibited substances, remain concentrated in the global northwest (Europe, North America, and Australia/New Zealand); awareness and use of TPT certification vary widely, and even in regions with established systems, athlete adherence is inconsistent. Barriers to low-risk supplement use are limited TPT availability, cost, differences in labeling (including language), and cultural factors. Firsthand experiences and perceptions highlight widespread misconceptions about supplement safety and certification. The authors recommend expanded athlete and team-around-the-athlete education, improved global access to TPT low-risk supplements, and policy initiatives to harmonize safety standards. This work emphasizes the need for coordinated international efforts to protect athlete health and integrity while allowing access to evidence-based supplementation.

Objective: This study examined the effects of different carbohydrate ingestion patterns on endurance cycling performance and gastrointestinal comfort. It was hypothesized that increasing carbohydrate availability in alignment with decreasing endogenous stores would optimize performance while minimizing gastrointestinal discomfort. Methods: Twelve trained male cyclists completed three randomized trials involving a 180-min intermittent cycling preload, a 15-min all-out performance test, and a maximal sprint to exhaustion. Participants ingested 90 g/hr of carbohydrates in an increasing (INC), decreasing (DEC), or constant (CON) pattern. Performance, substrate oxidation, rate of perceived exertion, and gastrointestinal comfort were assessed. Results: Carbohydrate distribution during exercise had no effect on 15-min all-out performance test (mean [95% confidence limits]: INC-CON -0.1% [-9.9, 11]; INC-DEC 5.9% [-8.6, 23]; DEC-CON -5.4 [-17, 7.8]) or time to exhaustion (INC-CON -0.6 [-3.8, 2.7]; INC-DEC 0.1 [-4.0, 4.4]; DEC-CON -0.7 [-4.0, 2.6]) performance. Carbohydrate oxidation was higher in DEC versus CON (7.1%; 2.7, 11.7) and versus INC (5.8%; -4.1, 15). Conversely, fat oxidation was lower in DEC versus CON (13%; -23, -1.8), while other contrasts were unclear. RPE was lower, but increased more over time in INC than CON. Nausea (standardized difference 1.2; 0.04, 2.3), stomach fullness (0.55; -0.15, 1.27), and abdominal cramping (0.84; -0.03, 1.7) increased over time in INC versus DEC. Conclusion: Carbohydrate intake distribution had little clear effect on performance, though a decreasing pattern may support oxidation and gut comfort later in exercise. Even intake remains advisable, but uneven patterns may be acceptable when needed.

Implementing a high-quality approach to the methodological classification and control of the ovarian hormone status of female participants in research is challenging and complex. These complexities have likely hindered the formulation of robust conclusions regarding the effects of the ovarian hormones (estrogen and progesterone) on sport science outcomes. We have therefore developed practical study design tools and resources to aid researchers in the pursuit of high-quality research in women. Specifically, this paper presents a tiered framework outlining varying levels of methodological classification and control of participant ovarian hormone status in exercise and performance studies involving postpubertal to premenopausal female participants. To support implementation, we also provide resources including a flowchart, participant prescreening questionnaire, and  examples of applying the tiering system in practice. These tools will assist researchers in planning and study design that adopts appropriate classification and control of ovarian hormone status of its participants. These guides have been generated from our experiences of implementing a high-quality approach in the applied sports science setting. We discuss the balance between methodological rigor, practical constraints, participant burden, and the generalizability of findings. Ultimately, this paper provides resources to assist researchers in adopting high-quality, suitable approaches to studying female athletes, regardless of available resources thereby facilitating the correction of sex-based research biases in the literature.

Cycling is one of the most popular sports worldwide, with competition events ranging from a few seconds (e.g., track sprint) to several days (e.g., road cycling 3-week Grand Tours). Professional cycling is arguably at the pinnacle of endurance sport demands due to the large number of events, range in durations, and variation in race conditions that these athletes must successfully negotiate. Numerous factors can affect performance in cycling, notably the type of event (e.g., track vs. road, single-day vs. multistage race); extrinsic conditions (e.g., race profile, weather conditions, altitude, team tactics); and individual variables (e.g., mental, physical, physiological, and technical attributes, nutritional strategies). In the present review, we aim to summarize the main factors underlying cycling performance. Particularly, we discuss current literature quantifying physiological and energetic demands imposed by races of different cycling modalities-albeit with a particular focus on road cycling-the factors associated with success in these races, the physical and physiological characteristics of elite/professional cyclists and their training regimens, and how these factors may be influenced by nutrition. Continued development in elite cycling requires a combination of traditional physiological markers with individual anthropometric and power-duration curve characteristics, as we move toward clustering of typologies and, ultimately, individual optimization of the training process.

Elite/professional cyclists often experience injuries and illnesses that lead to loss of training time/quality and reduced performance. Consequently, mitigating these problems is a high priority for multiple stakeholders, including athletes, coaches, sports medicine and allied health practitioners, and race organizers. This Union Cycliste Internationale-endorsed paper reviews the evidence for nutritional interventions in preventing and managing common injuries and illnesses in elite cycling, including skin injuries, upper respiratory tract infections, gastrointestinal disturbances, and sports-related concussions. Ensuring adequate protein (1.5-2.0 g·kg-1·day-1) and consumption of key micronutrients involved in wound healing (e.g., vitamin C and zinc) may optimize skin healing, albeit with no direct evidence in cyclists. Nutritional management strategies for upper respiratory tract infection include ingesting appropriate amounts of carbohydrate and protein to support training loads, optimizing vitamin D status, and possibly probiotic and polyphenol supplementation. Supplementation with other nutrients (omega-3 fats, glutamine, and vitamin C) also has come with some supportive, albeit mixed, evidence. Short-term low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diets; gut training; and use of mixed saccharide (glucose/maltodextrin-fructose) foods/supplements are evidence-supported strategies for reducing gastrointestinal symptoms, while probiotic supplementation, carbohydrate hydrogels, and cool/cold beverages currently have equivocal evidence. Promoting personal hygiene and food safety principles are important factors in avoiding gastrointestinal infections. Long-chain omega-3 fats and creatine monohydrate may reduce the severity of traumatic brain injuries, though supportive evidence is largely from animal models or based on head injury biomarkers in humans. Nutritional needs will ultimately vary depending on cycling discipline (road, track, cyclocross, mountain, and BMX), training and competitions loads, lifestyle, and environmental factors.

This study aimed to evaluate the effects of short-term oral L-arginine (ARG) supplementation on vascular parameters, nitric oxide (NO) concentration, and muscular performance during upper limb resistance exercise in healthy young men. A randomized, double-blind, crossover design was used with 16 recreationally trained men. Participants ingested ARG (3.2-9.6 g/day) or placebo for 4 days, separated by a 14-day washout. On the fourth day, they completed three sets of biceps curls at 65% of one-repetition maximum to concentric failure. Primary outcomes included total repetitions performed and fatigue ratio. Secondary outcomes comprised brachial artery diameter, peak systolic velocity, blood flow (velocity-time integral), vascular resistance index, plasma NO, and blood lactate concentrations. No significant differences were observed between ARG and placebo in muscular endurance (total repetitions, p = .305), volume load, or fatigue ratio. Plasma NO levels did not differ between conditions (p = .522). Although brachial artery diameter significantly increased 1-min postexercise in the ARG condition compared with placebo (p = .023), no differences were found for velocity-time integral, peak systolic velocity, resistance index, or blood pressure. Blood lactate concentrations rose after exercise in both groups, with a nonsignificant value in the ARG condition (p = .09 at 9-min postexercise). Short-term oral ARG supplementation did not enhance muscular endurance, systemic NO concentration, or vascular function during upper limb resistance exercise in healthy young men. Although a minor increase in brachial artery dilation was observed shortly after exercise, the effect was transient and insufficient to support meaningful ergogenic benefits.