In addition to the general nutritional guidelines described above, research has also demonstrated that timing and composition of meals consumed may play a role in optimizing performance, training adaptations, and preventing overtraining [2, 25, 40]. In this regard, it takes about 4 h for carbohydrate to be digested and assimilated into muscle and liver tissues as glycogen. Consequently, pre-exercise meals should be consumed about four to 6 h before exercise [40]. This means that if an athlete trains in the afternoon, breakfast can be viewed to have great importance to top off muscle and liver glycogen levels. Research has also indicated that ingesting a light carbohydrate and protein snack 30 to 60 min prior to exercise (e.g., 50 g of carbohydrate and 5 to 10 g of protein) serves to increase carbohydrate availability toward the end of an intense exercise bout [118, 119]. This also serves to increase availability of amino acids, decrease exercise-induced catabolism of protein, and minimize muscle damage [120,121,122]. Additionally, athletes who are going through periods of energy restriction to meet weight or aesthetic demands of sports should understand that protein intake, quality and timing as well as combination with carbohydrate is particularly important to maintain lean body mass, training effects, and performance [25]. When exercise lasts more than 1 h and especially as duration extends beyond 90 min, athletes should ingest glucose/electrolyte solutions (GES) to maintain blood glucose levels, prevent dehydration, and reduce the immunosuppressive effects of intense exercise [40, 123,124,125,126,127,128]. Notably, this strategy becomes even more important if the athlete is under-fueled prior to the exercise task or is fasted vs. unfasted at the start of exercise [68, 69, 129]. Following intense exercise, athletes should consume carbohydrate and protein (e.g., 1 g/kg of carbohydrate and 0.5 g/kg of protein) within 30 min after exercise and consume a high carbohydrate meal within 2 h following exercise [2, 74]. This nutritional strategy has been found to accelerate glycogen resynthesis as well as promote a more anabolic hormonal profile that may hasten recovery [120, 130, 131], but as mentioned above only when rapid glycogen restoration is needed or if the carbohydrate intake in the diet is adequate (
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ß-alanine, a non-essential amino acid, has ergogenic potential based on its role in carnosine synthesis [12]. Carnosine is a dipeptide comprised of the amino acids, histidine and ß-alanine, that naturally occur in large amounts in skeletal muscles. Carnosine is believed to be one of the primary muscle-buffering substances available in skeletal muscle. Studies have demonstrated that taking four to 6 g of ß-alanine orally, in divided doses, over a 28-day period is effective in increasing carnosine levels [418, 419], while more recent studies have demonstrated increased carnosine and efficacy up to 12 g per day [420]. According to the ISSN position statement, evaluating the existing body of ß-alanine research suggests improvements in exercise performance with more pronounced effects on activities lasting one to 4 min; improvements in neuromuscular fatigue, particularly in older subjects, and lastly; potential benefits in tactical personnel [12]. Other studies have shown that ß-alanine supplementation can increase the number of repetitions one can do [421], increase lean body mass [422], increase knee extension torque [423], and increase training volume [421]. In fact, one study also showed that adding ß-alanine to creatine improves performance over creatine alone [424]. While it appears that ß-alanine supplementation can improve performance, other studies have failed to demonstrate a performance benefit [425, 426]. 2ff7e9595c
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