This study describes the body composition, dietary nutrient intake, dietary practices, and biochemical indices of iron status of elite female American heptathletes during training. Four-day diet records and dietary practice questionnaires were obtained from 19 female heptathletes (26 ± 3 years) during the training season. Anthropometric measurements and fasting blood samples were obtained at the lowest phase of the training cycle. These athletes had a low body fat (13.8 ± 2.7%) and high fat-free mass to height ratios (33.0 ± 2.0 kg/m). Average nutrient intakes were > 67% of the reference intakes for all nutrients except vitamin E. Most dietary nutrient densities were higher than NHANES III nutrient densities for women 20–29 years old. More than 50% of the athletes took vitamin supplements and monitored their hydration status. Fifteen of the 17 athletes reported a normal menstrual cycle. Markers of biochemical iron status were all within the normal range. On average, these athletes were lean with high levels of fat free mass, adequate nutrient intakes, and normal biochemical indices of iron status. However, individual data reveals considerable variability within this group.
Veronica A. Mullins, Linda B. Houtkooper, Wanda H. Howell, Scott B. Going and C. Harmon Brown
P. Farajian, S.A. Kavouras, M. Yannakoulia and L.S. Sidossis
To investigate whether aquatic athletes follow optimal dietary intake, 58 athletes, all members of the Greek national swimming and water polo teams, were tested. Dietary intake was assessed at the nutrient, food, and food group level using the 24-h recall method and a food frequency questionnaire. Mean energy intake for males and females was 14.3 and 8.5 MJ, respectively. Mean carbohydrate consumption for male and female athletes was 4.5 g/kg and 3.8 g/kg of body weight, respectively. Fat intake was 153 g for males and 79 g for females. A significant number of the athletes (71% of the males, 93% of the females) did not meet the Dietary Reference Intakes for at least one of the antioxidant vitamins. The data suggest that athletes of both genders consumed too much fat and too little carbohydrate. Insufficient fruit and vegetable intake was related to low intake of antioxidants.
Lothar Rokitzki, Enno Logemann, Georg Huber, Elfriede Keck and Josef Keul
This study was undertaken to evaluate the effects of 5 months of α-tocopherol supplementation on physical performance during aerobic exercise training in 30 top-class cyclists. Antioxidative effects of supplementation were also studied. Plasma α-tocopherol concentration increased significantly in the vitamin E-supplemented group, whereas the placebo group showed a trend toward decrease. Physical performance did not improve in the α-tocopherol-supplemented group compared to the placebo group. Heart rates were also not significantly different. Lactate concentrations at the aerobic threshold and the anaerobic threshold were identical. Thus, there was no performance improvement in the α-tocopherol-supplemented group. However there was a significant reduction in CK in serum of the E-supplemented group. A trend toward decrease in GOT, GPT, and LDH was observed with α-tocopherol supplementation. Moreover, significantly reduced malondialdehyde serum levels were measured in the E-supplemented group. The findings indicate a protective effect of α-tocopherol supplementation against oxidative stress induced by strenuous exercise.
Athletes use a variety of nutritional ergogenic aids to enhance performance. Most nutritional aids can be categorized as a potential energy source, an anabolic enhancer, a cellular component, or a recovery aid. Studies have consistently shown that carbohydrates consumed immediately before or after exercise enhance performance by increasing glycogen stores and delaying fatigue. Protein and amino acid supplementation may serve an anabolic role by optimizing body composition crucial in strength-related sports. Dietary antioxidants, such as vitamins C and E and carotenes, may prevent oxidative stress that occurs with intense exercise. Performance during high-intensity exercise, such as sprinting, may be improved with short-term creatine loading, and high-effort exercise lasting 1-7 min may be improved through bicarbonate loading immediately prior to activity. Caffeine dosing before exercise delays fatigue and may enhance performance of high-intensity exercise.
Katsumi Sugiura, Izumi Suzuki and Kando Kobayashi
Mean daily intakes of energy and nutrients were surveyed from 3-day food records for 62 elite Japanese track-and-field athletes (28 males and 34 females) selected to participate in the 1994 Asian Championship games held in Hiroshima, Japan. Mean energy intakes of male and female athletes were 3,141 kcal (±592) and 2,508 kcal (±537), respectively. Based on the Japanese Recommended Dietary Allowances (JRDAs), long-distance and middle-distance runners had significantly higher energy and macronutrient intakes than did sprinters, jumpers, and throwers. There was no significant difference in micronutrient intake among the different types of athletes. However, of the sprinters, jumpers, and throwers. 15 males (54%) and 22 females (65%) consumed less than the JRDA for at least one micronutrient (i.e., vitamin or mineral). For some athletes, nutritional counseling that provides strategies for increasing food intake is recommended to optimize nutrient intake.
Jacqueline R. Berning, John P. Troup, Peter J. VanHandel, Jack Daniels and Nancy Daniels
Dietary food records from adolescent male and female swimmers participating in a national developmental training camp were analyzed for nutrient density. The mean caloric intake was 5,221.6 kcal for males and 3,572.6 kcal for females. The distribution of calories between carbohydrates, protein, and fat was not ideal for athletes trying to optimize performance. These young swimmers consumed too much fat and not enough carbohydrate. They consumed more than the RDA of vitamins A and C, and thiamine, riboflavin, and niacin; however, some concern is expressed for females who did not meet the RDA for calcium and iron. This study shows that although a group of adolescent swimmers may be consuming enough nutrients, individual swimmers may have very poor dietary habits and thus may not be providing adequate fuel or nutrients for optimal training or performance.
Dietary intakes of 24 female athletes in various sports were compared inseason and postseason to those reported by 24 nonathletes during the same time period. Diets were analyzed for energy, carbohydrate, fat, protein, vitamins A and C, thiamin, riboflavin, niacin, folacin, calcium, and iron. During the study, the athletes' and nonathletes' diets were similar. Their energy intakes were lower than recommended while their iron and calcium intakes were marginal (less than 70% of the recommended dietary allowance). Although few dietary changes were observed, the nonathletes' diets changed more than those of the athletes during the study. Both groups reduced their energy intakes but only the nonathletes' reduction was significant. Initially many subjects were dieting. More subjects reported dieting during the second recording period. These results suggest that the desire to be thin may influence dietary intakes of female athletes more than changes in exercise training.
Ben Desbrow, Nicholas A. Burd, Mark Tarnopolsky, Daniel R. Moore and Kirsty J. Elliott-Sale
Adolescent, female, and masters athletes have unique nutritional requirements as a consequence of undertaking daily training and competition in addition to the specific demands of age- and gender-related physiological changes. Dietary education and recommendations for these special population athletes require a focus on eating for long-term health, with special consideration given to “at-risk” dietary patterns and nutrients (e.g., sustained restricted eating, low calcium, vitamin D and/or iron intakes relative to requirements). Recent research highlighting strategies to address age-related changes in protein metabolism and the development of tools to assist in the management of Relative Energy Deficiency in Sport are of particular relevance to special population athletes. Whenever possible, special population athletes should be encouraged to meet their nutrient needs by the consumption of whole foods rather than supplements. The recommendation of dietary supplements (particularly to young athletes) overemphasizes their ability to manipulate performance in comparison with other training/dietary strategies.
Ian P. Snider, Terry L. Bazzarre, Scott D. Murdoch and Allan Goldfarb
This study examined the effects of the Coenzyme Athletic Performance System (CAPS) on endurance performance to exhaustion. CAPS contains 100 mg coenzyme Q10,500 mg cytochrome C, 100 mg inosine, and 200 IU vitamin E. Eleven highly trained male triathletes were given three daily doses of either CAPS or placebo (dicalcium phosphate) for two 4-week periods using a double-blind crossover design. A 4-week washout period separated the two treatment periods. An exhaustive performance test, consisting of 90 minutes of running on a treadmill (70%
Sakuko Ishizaki, Takako Koshimizu, Kae Yanagisawa, Yoshiko Akiyama, Yuko Mekada, Nobuhiro Shiozawa, Noriko Takahaski, Jun Yamakawa and Yukari Kawano
This study was to assess the effect of a fixed dietary intake on biomarkers of red blood cell (RBC) biosynthesis and degradation. Over a two-year period, eight collegiate rhythmic gymnasts participated in this study. During the first year, they ate self-selected diets. During the second year, a fixed dietary intake involving consumption of common Japanese foods containing 15 mg iron and 1500 kcal energy was maintained for 4 wk at the beginning of the program. Fixed dietary intakes resulted in significantly increased intakes of protein, minerals and vitamins, and significantly decreased fat intake, but total energy and carbohydrate intakes were unchanged. Mean values of RBC, Hb, Ht, or TIBC were not affected by the intervention. A fixed dietary intervention appeared to enhance RBC turnover by increasing the capacity for erythrocyte biosynthesis and degradation, although the prevalence of iron-deficiency anemia remained unchanged.