Effects of dietary supplements on athletic performance in elite soccer players: a systematic review.

Dietary supplements are widely used among athletes, and soccer players are no exception. Nevertheless, evidence supporting the use of dietary supplements aiming to enhance performance in soccer is somewhat contradictory, scarce, or even nonexistent. Thus, the present study aimed to systematically review and synthesize the effects of dietary supplements on athletic performance (e.g. distance covered, sprinting, jump performance) in elite soccer players. Studies enrolling highly trained, elite, and world-class soccer players using dietary supplements were searched in MEDLINE/PubMed, Web of Science, Scopus, and EBSCO databases in June 2022. In total, 1043 studies were identified, and 18 met the eligibility criteria. The studies evaluated the impacts on athletic performance of several dietary supplements, including caffeine, creatine, protein, beverages with carbohydrates and electrolytes, tart cherry juice, nitrate-rich beetroot juice, sodium bicarbonate with minerals, yohimbine, and a proprietary nutraceutical blend. Caffeine supplementation in doses between 3 and 6 mg/kg of body mass may improve jump height and sprint ability, particularly in female players, but individual response to caffeine must be considered. Creatine may improve sprint, agility, and in female players, jump performance. Protein supplementation can improve sprint and jump performance between matches, especially if protein ingested from food is not up to recommendations. Beverages containing carbohydrates and electrolytes can be used as part of the strategies to achieve carbohydrate intake during training and match-days but used alone do not benefit athletic performance. Tart cherry juice might be useful for maintaining athletic performance after matches that produce higher force loss and exercise-induced muscle damage, although polyphenols from the diet might attenuate the effects of tart cherry supplementation. Nitrate-rich beetroot concentrate can attenuate performance decrease in the days following matches. Further investigation with sodium bicarbonate alone is necessary, as supplementation protocols with elite players included other substances. Finally, the available data does not support yohimbine supplementation or the use of Resurgex Plus® to improve athletic performance in elite soccer players. Still, more well-designed research with elite soccer players is needed to improve support and advice regarding the use of dietary supplements for athletic performance enhancement.

A Novel Plant-Based Protein Has Similar Effects Compared to Whey Protein on Body Composition, Strength, Power, and Aerobic Performance in Professional and Semi-Professional Futsal Players.

Introduction: The effects of dietary protein on body composition and physical performance seemingly depend on the essential amino acid profile of the given protein source, although controversy exists about whether animal protein sources may possess additional anabolic properties to plant-based protein sources. Purpose: To compare the effects of a novel plant-based protein matrix and whey protein supplementation on body composition, strength, power, and endurance performance of trained futsal players. Methods: Fifty male futsal players were followed during 8 weeks of supplementation, with 40 completing the study either with plant-based protein (N = 20) or whey protein (N = 20). The following measures were assessed: bone mineral content, lean body mass, and fat mass; muscle thickness of the rectus femoris; total body water; blood glucose, hematocrit, C-reactive protein, aspartate aminotransferase, alanine aminotransferase, creatine kinase, creatinine, and estimated glomerular filtration rate; salivary cortisol; maximal strength and 1-RM testing of the back squat and bench press exercises; muscle power and countermovement jump; VO2max and maximal aerobic speed. Subjects were asked to maintain regular dietary habits and record dietary intake every 4 weeks through 3-day food records. Results: No differences in any variable were observed between groups at baseline or pre- to post-intervention. Moreover, no time*group interaction was observed in any of the studied variables, and a time effect was only observed regarding fat mass reduction. Conclusions: Supplementing with either a novel plant-based protein matrix or whey protein did not affect any of the variables assessed in high-level futsal players over 8 wks. These results suggest that whey protein does not possess any unique anabolic properties over and above those of plant-based proteins when equated to an essential amino acid profile in the population studied. Furthermore, when consuming a daily protein intake >1.6 g/kg BW.day-1, additional protein supplementation does not affect body composition or performance in trained futsal players, regardless of protein type/source.

Dietary strategies to recover from exercise-induced muscle damage.

Exhaustive or unaccustomed intense exercise can cause exercise-induced muscle damage (EIMD) and its undesirable consequences may decrease the ability to exercise and to adhere to a training programme. This review briefly summarises the muscle damage process, focusing predominantly on oxidative stress and inflammation as contributing factors, and describes how nutrition may be positively used to recover from EIMD. The combined intake of carbohydrates and proteins and the use of antioxidants and/or anti-inflammatory nutrients within physiological ranges are interventions that may assist the recovery process. Although the works studying food instead of nutritional supplements are very scarce, their results seem to indicate that food might be a favourable option as a recovery strategy. To date, the only tested foods were milk, cherries, blueberries and pomegranate with promising results. Other potential solutions are foods rich in protein, carbohydrates, antioxidants and/or anti-inflammatory nutrients.

Nutrition and nutritional issues for dancers.

Proper nutrition, not simply adequate energetic intake, is needed to achieve optimal dance performance. However, little scientific research exists concerning nutrition in dance, and so, to propose nutritional guidelines for this field, recommendations need to be based mainly on studies done in other physically active groups. To diminish the risk of energy imbalance and associated disorders, dancers must consume at least 30 kcal/kg fat-free mass/day, plus the training energy expenditure. For macronutrients, a daily intake of 3 to 5 g carbohydrates/kg, 1.2 to 1.7 g protein/kg, and 20 to 35% of energy intake from fat can be recommended. Dancers may be at increased risk of poor micronutrient status due to their restricted energy intake; micronutrients that deserve concern are iron, calcium, and vitamin D. During training, dancers should give special attention to fluid and carbohydrate intake in order to maintain optimal cognition, motivation, and motor skill performance. For competition/stage performance preparation, it is also important to ensure that an adequate dietary intake is being achieved. Nutritional supplements that may help in achieving specific nutritional goals when dietary intake is inadequate include multivitamins and mineral, iron, calcium, and vitamin D supplements, sports drinks, sports bars, and liquid meal supplements. Caffeine can also be used as an ergogenic aid. It is important that dancers seek dietary advice from qualified specialists, since the pressure to maintain a low body weight and low body fat levels is high, especially in styles as ballet, and this can lead to an unbalanced diet and health problems if not correctly supervised.

Antioxidants do not prevent postexercise peroxidation and may delay muscle recovery.

PURPOSE: This study aimed to determine the effects of 4 wk of antioxidants (AOX) supplementation on exercise-induced lipid peroxidation, muscle damage, and inflammation in kayakers. METHODS: Subjects (n = 20) were randomly assigned to receive a placebo (PLA) or an AOX capsule (AOX; 272 mg of alpha-tocopherol, 400 mg of vitamin C, 30 mg of beta-carotene, 2 mg of lutein, 400 mug of selenium, 30 mg of zinc, and 600 mg of magnesium). Blood samples were collected at rest and 15 min after a 1000-m kayak race, both before and after the supplementation period, for analysis of alpha-tocopherol, alpha-carotene, beta-carotene, lycopene, lutein plus zeaxanthin, vitamin C, uric acid, total AOX status (TAS), thiobarbituric reactive acid substances (TBARS) and interleukin-6 (IL-6) levels, and creatine kinase (CK), superoxide dismutase (SOD), glutathione reductase (Gr), and glutathione peroxidase (GPx) activities. RESULTS: With supplementation, plasma alpha-tocopherol (P = 0.003) and beta-carotene (P = 0.007) augmented significantly in the AOX group. IL-6 (exercise, P = 0.039), TBARS (exercise, P < 0.001), and uric acid (exercise, P = 0.032) increased significantly in response to the exercise regardless of treatment group. Cortisol level raised more from pre- to postsupplementation period in the PLA group (time x supplementation, P = 0.002). Although TAS declined after exercise before intervention, it increased above preexercise values after the 4-wk period in the AOX group (supplementation x time x exercise, P = 0.034). CK increased after exercise in both groups (exercise effect, P < 0.001) and decreased from week 0 to week 4 more markedly in the PLA group (supplementation x time, P = 0.049). CONCLUSIONS: AOX supplementation does not offer protection against exercise-induced lipid peroxidation and inflammation and may hinder the recovery of muscle damage.