Quercetin, a natural polyphenolic flavonoid substance present in a variety of food plants, has been shown in vitro and in animal studies to have widespread health and performance benefits resulting from a combination of biological properties, including antioxidant and anti-inflammatory activity, as well as the ability to increase mitochondrial biogenesis. Little is known about these effects in humans, however, especially with respect to exercise performance. The authors determined whether quercetin ingestion would enhance maximal aerobic capacity and delay fatigue during prolonged exercise in healthy but untrained participants. Twelve volunteers were randomly assigned to 1 of 2 treatments: (a) 500 mg of quercetin twice daily dissolved in vitamin-enriched Tang or (b) a nondistinguishable placebo (Tang). Baseline VO2max and bike-ride times to fatigue were established. Treatments were administered for a period of 7 days using a randomized, double-blind, placebo-controlled, crossover study design. After treatment both VO2max and ride time to fatigue were determined. Seven days of quercetin feedings were associated with a modest increase in VO2max (3.9% vs. placebo; p < .05) along with a substantial (13.2%) increase in ride time to fatigue (p < .05). These data suggest that as little as 7 days of quercetin supplementation can increase endurance without exercise training in untrained participants. These benefits of quercetin may have important implications for enhancement of athletic and military performance. This apparent increase in fitness without exercise training may have implications beyond that of performance enhancement to health promotion and disease prevention.
J. Mark Davis, Catherine J. Carlstedt, Stephen Chen, Martin D. Carmichael and E. Angela Murphy
Sherry Robertson, Dan Benardot and Margo Mountjoy
The sport of synchronized swimming is unique, because it combines speed, power, and endurance with precise synchronized movements and high-risk acrobatic maneuvers. Athletes must train and compete while spending a great amount of time underwater, upside down, and without the luxury of easily available oxygen. This review assesses the scientific evidence with respect to the physiological demands, energy expenditure, and body composition in these athletes. The role of appropriate energy requirements and guidelines for carbohydrate, protein, fat, and micronutrients for elite synchronized swimmers are reviewed. Because of the aesthetic nature of the sport, which prioritizes leanness, the risks of energy and macronutrient deficiencies are of significant concern. Relative Energy Deficiency in Sport and disordered eating/eating disorders are also of concern for these female athletes. An approach to the healthy management of body composition in synchronized swimming is outlined. Synchronized swimmers should be encouraged to consume a well-balanced diet with sufficient energy to meet demands and to time the intake of carbohydrate, protein, and fat to optimize performance and body composition. Micronutrients of concern for this female athlete population include iron, calcium, and vitamin D. This article reviews the physiological demands of synchronized swimming and makes nutritional recommendations for recovery, training, and competition to help optimize athletic performance and to reduce risks for weight-related medical issues that are of particular concern for elite synchronized swimmers.
Flatwater kayaking requires upper-body muscle strength and a lean body composition. This case study describes a nutrition intervention with a 19-year-old male elite sprint kayaker to increase muscle mass and improve recovery posttraining. Before the intervention, average daily energy intake was 13.6 ± 2.5 MJ (M ± SD; protein, 1.8 g/kg; carbohydrate, 3.6 g/kg), and the athlete was unable to eat sufficient food to meet the energy demands of training. During the 18-month intervention period, the athlete’s daily energy intake increased to 22.1 ± 3.8 MJ (protein, 3.2 g/kg; carbohydrate, 7.7 g/kg) by including milk-based drinks pre- and posttraining and before bed and an additional carbohydrate-based snack midmorning. This simple dietary intervention, along with a structured strength and conditioning program, resulted in an increase of 10 kg body mass with minimal change in body fat percentage. Adequate vitamin D status was maintained without the need for supplementation during the intervention period. In addition, the athlete reported the milk-based drinks and carbohydrate snacks were easy to consume, and no adverse side effects were experienced. This was the first time the athlete was able to maintain weight during intensive phases of the training cycle.
Ben Desbrow, Joanna McCormack, Louise M. Burke, Gregory R. Cox, Kieran Fallon, Matthew Hislop, Ruth Logan, Nello Marino, Susan M. Sawyer, Greg Shaw, Anita Star, Helen Vidgen and Michael Leveritt
It is the position of Sports Dietitians Australia (SDA) that adolescent athletes have unique nutritional requirements as a consequence of undertaking daily training and competition in addition to the demands of growth and development. As such, SDA established an expert multidisciplinary panel to undertake an independent review of the relevant scientific evidence and consulted with its professional members to develop sports nutrition recommendations for active and competitive adolescent athletes. The position of SDA is that dietary education and recommendations for these adolescent athletes should reinforce eating for long term health. More specifically, the adolescent athlete should be encouraged to moderate eating patterns to reflect daily exercise demands and provide a regular spread of high quality carbohydrate and protein sources over the day, especially in the period immediately after training. SDA recommends that consideration also be given to the dietary calcium, Vitamin D and iron intake of adolescent athletes due to the elevated risk of deficiency of these nutrients. To maintain optimal hydration, adolescent athletes should have access to fluids that are clean, cool and supplied in sufficient quantities before, during and after participation in sport. Finally, it is the position of SDA that nutrient needs should be met by core foods rather than supplements, as the recommendation of dietary supplements to developing athletes over-emphasizes their ability to manipulate performance in comparison with other training and dietary strategies.
Mandy Clark, Debra B. Reed, Stephen F. Crouse and Robert B. Armstrong
Little published data describe the dietary and physiological profiles of intercollegiate female soccer players; therefore, the purpose of this investigation was to report baseline dietary data, anthropometrics, and performance indices of soccer women during rigorous pre-season training (2 sessions/day) and then during the post-competitive season. Members of a NCAA Division I women’s soccer squad completed 3-day diet records, anthropometrics, and physical tests, including VO2peak. Average body mass was 62 kg with 16% body fat, and no significant pre to post differences were observed. Total energy, carbohydrate (CHO), protein, and fat intakes were significantly greater during the pre-sea-son. Pre-season energy intake met the DRI for females with an “active” lifestyle (37 kcal/kg). While CHO intake failed to meet minimum recommendations to promote glycogen repletion (7–10 g/kg), protein and fat intakes were above minimum recommendations. Pre- and post-season intakes of several micronu-trients were marginal (<75% of the DRI) including vitamin E, folate, copper, and magnesium. VO2peak significantly improved from pre- to post-season (42 and 50 ml/kg/min). In this study female soccer players appeared to meet caloric needs during periods of training but failed to meet minimum CHO and micronu-trient recommendations. Foods higher in protein and fat displaced more CHOrich and nutrient-dense foods within athletes’ energy requirements and satiety limits.
Susan Heaney, Helen O’Connor, Janelle Gifford and Geraldine Naughton
This study aimed to compare strategies for assessing nutritional adequacy in the dietary intake of elite female athletes.
Dietary intake was assessed using an adapted food-frequency questionnaire in 72 elite female athletes from a variety of sports. Nutritional adequacy was evaluated and compared using mean intake; the proportion of participants with intakes below Australian nutrient reference values (NRV), U.S. military dietary reference intakes (MDRI), and current sports nutrition recommendations; and probability estimates of nutrient inadequacy.
Mean energy intake was 10,551 ± 3,836 kJ/day with macronutrient distribution 18% protein, 31% fat, and 46% carbohydrate, consistent with Australian acceptable macronutrient distribution ranges. Mean protein intake (1.6 g · kg−1 · d−1) was consistent with (>1.2 g · kg−1 · d−1), and carbohydrate intake (4.5 g · kg−1 · d−1), below, current sports nutrition recommendations (>5 g · kg−1 · d−1), with 30% and 65% of individuals not meeting these levels, respectively. Mean micronutrient intake met the relevant NRV and MDRI except for vitamin D and folate. A proportion of participants failed to meet the estimated average requirement for folate (48%), calcium (24%), magnesium (19%), and iron (4%). Probability estimates of inadequacy identified intake of folate (44%), calcium (22%), iron (19%), and magnesium (15%) as inadequate.
Interpretation of dietary adequacy is complex and varies depending on whether the mean, proportion of participants below the relevant NRV, or statistical probability estimate of inadequacy is used. Further research on methods to determine dietary adequacy in athlete populations is required.
Anna Baylis, David Cameron-Smith and Louise M. Burke
Many athletes report using a wide range of special sports foods and supplements. In the present study of 77 elite Australian swimmers, 99% of those surveyed reported the use of these special preparations, with 94% of swimmers reporting the use of non-food supplements. The most popular dietary supplements were vitamin or mineral supplements (used by 94% of the group), herbal preparations (61%), and creatine (31%). Eighty-seven percent of swimmers reported using a sports drink or other energy-providing sports food. In total, 207 different products were reported in this survey. Sports supplements, particularly supplements presented as pills or other non-food form, are poorly regulated in most countries, with little assurance of quality control. The risk of an inadvertent “positive doping test” through the use of sports supplements or sports foods is a small but real problem facing athletes who compete in events governed by anti-doping rules. The elite swimmers in this survey reported that information about the “doping safety” of supplements was important and should be funded by supplement manufacturers. Although it is challenging to provide such information, we suggest a model to provide an accredited testing program suitable for the Australian situation, with targeted athlete education about the “sports safety” of sports supplements and foods.
Kathryn Froiland, Wanda Koszewski, Joshua Hingst and Lisa Kopecky
A survey was conducted to examine the source of information and usage of nutritional supplements in 115 male and 88 female varsity athletes at a Division I university. The survey asked each athlete to define supplement, and report supplement use and type, source of information, and reasons for use. Supplement use frequencies were determined, and comparisons were made between gender and sport. Eighty-nine percent of the subjects had or were currently using nutritional supplements. Many athletes did not consider sports drinks and calorie replacement products as supplements. Females were more likely to take calcium and multivitamins, and males had significant intake for ginseng, amino acids, glutamine, hydroxy-methyl-buterate (HMB), weight gainers, whey protein, and Juven. The most frequently used supplements overall were energy drinks (73%), calorie replacement products of all types (61.4%), multivitamin (47.3%), creatine (37.2%), and vitamin C (32.4%). There was also significant supplement use noted per sport. Females were more likely to obtain information from family members regarding supplementation, and males from a store nutritionist, fellow athletes, friends, or a coach. Female athletes were more likely to take supplements for their health or because of an inadequate diet, while men reported taking supplements to improve speed and agility, strength and power, or for weight/muscle gain.
Ina Garthe and Ronald J. Maughan
, categories include sports foods (gels, bars, drinks, protein powders), vitamins and minerals, herbals and botanicals, and ergogenic supplements (Table 1 ). In addition, there is a category which includes supplements for weight loss, products for increased libido, and there are also gluten-free, lactose
Amanda Zaleski, Beth Taylor, Braden Armstrong, Michael Puglisi, Priscilla Clarkson, Stuart Chipkin, Charles Michael White, Paul D. Thompson and Linda S. Pescatello
, CT for the quantitative determination of total serum 25(OH)D via standard electrochemiluminescence binding assay (Elecsys Vitamin D Assay; Roche Diagnostics, Indianapolis, IN). The intra- and interassay coefficients of variation for these analyses were 5.3% and 4.6%, respectively. Resting BP and HR