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.

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.

Track cycling is a unique discipline whereby events take place on a velodrome using fixed-gear bicycles. Events cover a spectrum of durations ranging from <11 s through to ∼60 min. Therefore, diverse and specialized physiological attributes are required to meet the specific demands of competition. Nutrition has a fundamental role in optimizing athlete performance through maintaining overall health, fueling training to develop the required physiological characteristics for success and enabling athletes to meet the energy demands of competition. This review will focus on how nutrition can be optimized to best support the training periodization and competition requirements and provide practical recommendations on fueling strategies for track cycling.

The fundamental goal of nutrition for training is to provide the required energy and substrate to sustain the target training volume and intensity that is necessary to induce desired physiological adaptations. However, aside from fueling and recovery, it is now recognized that nutrient availability also modulates the activation of cell signaling pathways that regulate adaptations associated with both endurance and strength training. Such developments are the guiding principles underpinning "nutritional periodization" wherein energy, macronutrient, and micronutrient availability are deliberately manipulated across the microcycle, mesocycle, and macrocycle with the strategic goal to promote training adaptations, support recovery, manipulate body composition, and optimize competition performance. In addition to total "daily" nutrient intake, the elite athlete must, therefore, adjust their energy and carbohydrate intake in a meal-by-meal and day-by-day manner (i.e., carbohydrate periodization) in accordance with the energetic demands and training objectives of each specific training session. In addition to fueling (and refueling) for the work required, daily protein intake should at least be 1.6-2.1 g·kg-1·day-1 not only to account for amino acid oxidation during exercise but also, importantly, to promote tissue remodeling, notably skeletal muscle. Emerging evidence also supports the rationale for nutraceuticals to promote recovery and sleep, though the potential effect of such compounds in blunting training adaptation should also be considered. Taken together, it is increasingly clear that nutrition is a critical enabler to successful training outcomes, and as such, the sport nutritionist should be considered an integral member of an athlete's coaching and performance support team.

Bicycle motorcross racing is a unique sprint cycling discipline that takes place on a 300- to 450-m outdoor track with an 8-m start hill. A single race is 30-40 s in duration, and athletes can compete in up to seven races per day. Athletes require highly specific physiological attributes to meet the training and competition demands, and successful riders can produce high peak power outputs and demonstrate technical and tactical superiority over their opponents. Nutrition has a key role in optimizing athlete health, training adaptations, and overall athlete performance. This review will focus on the training and race demands for bicycle motorcross race and fueling strategies to support training and racing outcomes.