International journal of sport nutrition and exercise metabolism最新文献

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.

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.

We investigated the effects of 8-weeks of eccentric resistance exercise (RE) with hydrolyzed collagen supplementation on patellar tendon (PT) cross-sectional area (CSA), vastus lateralis (VL) muscle size, maximum voluntary force  (MVF), and peak rate of force development (pRFD) in international female field hockey Master athletes. Twenty-two premenopausal women (37 ± 2 years, 68.9 ± 8.0 kg, and 1.68 ± 0.04 m) were randomly assigned to collagen (COL; n = 10) and placebo (PLA; n = 12) cohorts in a triple-blind design. They completed three eccentric RE sessions per week for 8 weeks in addition to their regular hockey training. Before each RE session, participants ingested 30 g hydrolyzed COL or 32.9 g maltodextrin (PLA), together with 500 mg vitamin C. Pre- and postintervention, we assessed MVF and pRFD during a voluntary multijoint isometric muscle contraction and countermovement jump height, and VL thickness and PT CSA were measured with ultrasonography. MVF increased from 892 ± 366 to 1,011 ± 420 N (p = .020) and VL thickness increased from 21 ± 3 to 22 ± 3 mm (p = .015), with no Group × Time interactions (p > .05), whereas countermovement jump height did not change (p = .238). PT CSA increased in both groups (p < .001) but more in COL (116 ± 12 to 121 ± 13 mm2) than PLA (109 ± 22 to 111 ± 22 mm2, p = .014). Similarly, pRFD increased in both groups (p = .002) but more in COL (7.9 ± 1.3 to 10.1 ± 2.4 kN/s) than PLA (8.2 ± 2.4 to 9.6 ± 2.9 kN/s, p = .039). Therefore, hydrolyzed collagen supplementation enhanced gains in PT CSA and pRFD following 8 weeks of eccentric RE in elite female field hockey Master athletes, thus providing an effective strategy to improve physical performance in this underresearched population.

Technological innovations can provide cyclists and their support team additional data. These data have potential to improve understanding of performance determinants and could be used to identify and tailor nutritional strategies to improve cycling performance. This potential, however, is dependent on the quality, interpretation, and practical use of the data generated. In this review, several technologies that are used or have some potential for use, in professional cycling are discussed. These include power meters, continuous glucose monitors, portable sweat and lactate analyzers, noninvasive estimation of muscle fiber typology, ultrasound for muscle glycogen concentrations and subcutaneous fat quantification, noninvasive core body temperature sensors, and portable substrate metabolism analyzers. The evidence regarding the validity of these technologies is critically evaluated, alongside a discussion of the potential rationale (or lack thereof) for their use in guiding nutritional strategies. Some of these technologies have sufficient validity and reliability to provide data of sufficient quality and, combined with appropriate rationale, can inform some nutritional strategies (e.g., energy expenditure from power meters). In contrast, other technologies either have insufficient rationale to inform a nutritional strategy or currently lack the validity and/or reliability to provide data of sufficient quality to inform nutritional strategies. Practitioners working with athletes are recommended to consider whether there is any practical value in each metric and, if so, then consider the validity and reliability of a method to measure such a metric before implementation.

The Union Cycliste Internationale recognizes several mountain biking (MTB) disciplines, including downhill, enduro, cross-country short track, cross-country Olympic, cross-country marathon, and multiday stage racing. Cyclocross is recognized as a separate cycling discipline. Both MTB and cyclocross include cycling on off-road surfaces of varying technicality on specialized bicycles purposed for the respective disciplines. The various discipline-specific racing formats and intensities dictate nutritional recommendations. High-paced race starts and high average race intensities support standard recommendations for caffeine and carbohydrate ingestion before and during racing and the adoption of recovery nutrient guidelines, tailored for each discipline. Notably, current quantification methods underestimate exercise intensity and exercise energy expenditure (EEE) in MTB and cyclocross because of the inability to quantify the additional energy cost of isometric contractions associated with bicycle handling while negotiating obstacles and dampening vibrations. Therefore, deriving EEE and target energy intake based on power measurements provide only minimum estimates, requiring a correction factor. Accordingly, minimum target energy intake should equate to the sum of power-derived EEE, +0.24 kcal·kg-1·km-1 off-road, resting metabolic rate, and an additional 0.45-fold resting metabolic rate (for nonexercise activity). Daily training nutrition based on standard guidelines is tailored by discipline, expected intensity, duration, and training EEE. Guidelines apply equally to both sexes. In addition, certain nutritional practices are suggested to support long-term bone health for MTB and cyclocross athletes.

Caffeine (CAF) mouth rinsing has been considered a practical nutritional strategy among athletes. Recent studies indicate that this nutritional strategy's efficacy may depend on the athlete's prandial state. Therefore, the main aim of the current study is to determine the effect of CAF mouth rinsing on a battery of soccer-specific tests of soccer players in fasted (FST) or fed states (FED). Thirteen male soccer players (age: 18.1 ± 0.9 years, body mass: 60.1 ± 8.4 kg, height: 174.2 ± 7.3 cm, and body mass index: 20.14 ± 2.7 kg/m2) randomly participated in a randomized, double-blind, Latin square study design. Participants completed four experimental trials while performing eight serial mouth rinses of 750-mg CAF or a taste-matched placebo (PLA) for 15 s and then immediately expectorated. Two trials commenced 2 hr after a high-carbohydrate breakfast (FED), and two trials were performed after an overnight fast (FST). Following the final mouth rinse, sprint test, countermovement jump, Yo-Yo Intermittent Recovery Test Level 1, and rating of perceived exertion were measured, respectively. There was a main effect of condition for Yo-Yo Intermittent Recovery Test Level 1 performance (p = .021), while interaction between Condition × Prandial (p = .671) and the main effect of prandial state (p = .437) was not significant for Yo-Yo Intermittent Recovery Test Level 1 (CAF-FST = 2,155 ± 484 m, PLA-FST = 1,933 ± 549 m, CAF-FED = 2,098 ± 679 m, and PLA-FED = 1,864 ± 535 m). In addition, there was no significant main effect of condition, prandial, and interaction between Condition × Prandial for the sprint test and countermovement jump and the rating of perceived exertion (all p > .5). These data suggest that CAF mouth rinsing increases intermittent running performance in soccer players. This improvement is likely to be similar in the FST and FED states.