and 50 kcal kg–1 per day, respectively. This may be a helpful target for those working with athletes and is similar to what is suggested by Manore et al. (2007).
Using EI data from dietary records in combination with stable body weight has also been recommended as a tool for determining energy needs of athletes.
That these data can accurately reflect energy requirement of athletes should not be assumed and several factors should be considered when using dietary intake data to estimate TDEE in gymnasts. As mentioned above, underreporting of dietary intake occurs in individuals and groups. Especially in sports such as the gymnastic disciplines that emphasize leanness and thinness, it should be expected that EI is underreported. Other issues of using EI to gauge energy needs in athletes relate to energy efficiency. For example, reported EI of gymnasts do not seem to be very high (Jonnalagadda et al., 1998; Michopoulou et al., 2011). Does this mean that gymnasts have grown accustomed to long-term underfeeding? If true, reported EI is expected to meet the newly established, however, suppressed TDEE.
There are a few other approaches to evaluate whether a gymnasts eats enough, without having to assess two highly biased variables, EI and TDEE. First, evaluating changes in body weight and composition for the purpose of nutritional, and especially caloric, adequacy can be an effective approach, especially if used over time. However, in athletes with disordered and/or restrictive eating, energy efficiency may again complicate the professional’s ability to evaluate the athlete using body weight and composition. While no follow-up studies have confirmed this, Duetz et al. (2000) showed a significant association between the energy deficits incurred throughout the day and percent body fat. This study compared gymnasts to runners and showed that runners who appeared to graze throughout the day had less body fat than gymnasts who seem more prone to energy restriction throughout the day. Interestingly, both groups experienced a similar energy deficit at the end of the day, but grazing versus dieting for prolonged periods of time was associated with lower body fat levels in runners versus gymnasts (Duetz et al., 2000). Thus, it is possible that gymnasts who chronically diet are at greater risk for low RMR and increased fat storage to preserve energy. These athletes are also expected to be more resistant to a weight loss program, and thus, may struggle more to attain and maintain a lean physique.
Another valuable tool to evaluate adequacy of EI is menstrual regularity, as menstrual dysfunction may indicate a low EI, high EEE, or a combination of the two. A diet reduced in calories may simply be too low to meet all physiologic functions beyond what is necessary for exercise. This concept is referred to as energy availability (EA) and is derived by EEE subtracted from EI. For female athletes in particular, reducing EI, while continuing with hard training poses a risk due to the link between low EA and menstrual dysfunction. Thus, an irregular or absent menstrual cycle may well indicate that the athlete is not consuming enough calories to meet the demands of the sport and daily energy needs for growth and repair. Menstrual dysfunction is one of the components of the female athlete triad (Nattiv et al., 2007). While an athlete not eating enough may jeopardize endocrine function, she/he is also at risk for acute effects that may interfere with performance, including glycogen depletion, micronutrient deficiencies, and fatigue. Manore et al. (2007) proposed the following guidelines for maintaining EA in exercising women during various phases of weight loss, maintenance, growth, and recovery (Table 5.1). These values can be used to evaluate at least a female athlete’s EI relative to various phases of training, competition, and/or growth. To date, there are no recommendations for male athletes, although it may be that similar targets apply due to the relative expression (i.e., body weight) of these values.
Taking into consideration the methodological challenges and the limitations related to EI data, Table 5.1 shows that EI in gymnasts varies and EI reported is well below expected requirement, although this is dependent on gender, age, performance level, and gymnastic discipline. Some studies report that the adolescent gymnast has adequate intake, however, the majority of the studies report insufficient EI and daily energy deficits in both adolescent and older female gymnasts (Jonnalagadda et al., 1998; Michopoulou et al., 2011). There are very few data on male gymnasts. However, from the studies reviewed it seems that male gymnasts report a more adequate EI. While the low reported EI in female gymnasts may reflect underreporting or energy efficiency issues, it may also be due to their attitudes about diet and body image. There are several concerns regarding a low EI, especially in athletes with heavy training loads. Low EI will, in most cases, lead to insufficient macro- and micronutrient intakes. When low EI is reported, it also commonly shows a lower than optimal carbohydrate and protein intake.
Carbohydrates provide energy for performance and recovery and exhibit a protein sparing effect. Gymnasts undergoing moderate, repetitive, skill-based training require a carbohydrate intake of at least 3 g kg–1 per day (Burke et al., 2011) and up to 5–6 g kg–1 per day if subjected to higher training loads (Burke et al., 2011). Most gymnasts, training 5–6 hours per day, need a carbohydrate intake of between 5 and 6 g kg–1 per day, which in absolute terms ranges from 250 to 300 g of carbohydrate per day for a female athlete weighing 50 kg. For carbohydrate, reduced intakes (~3 g kg–1 per day) in gymnasts are not problematic, as long as the athlete understands the importance of increasing carbohydrate with greater training intensity or volume. Carbohydrate adequacy is essential for the maintenance of glycogen stores and the ability to recover from training on a daily basis. Depleting glycogen stores during heavy training may pose both performance and health risks to the athlete. Obviously, when needed, weight loss and body composition manipulations should be attempted during off-season and low-intensity training phases. However, this is not always possible nor is it practical. Therefore, utmost attention should be paid to carbohydrate adequacy and a minimum level of 3 g kg–1 per day (Burke et al., 2011) should be met by both artistic and rhythmic gymnasts. While dietary assessment methods can help evaluate carbohydrate intake, performance indices along with subjective ratings of fatigue, mood state, hours of sleep, in combination with interdisciplinary approaches to monitor performance and health in the athlete can help evaluate overall stress and risk for underrecovery and overtraining related to carbohydrate inadequacy.
When it comes to protein intakes in gymnasts there are no specific recommendations. The recommended daily allowance (RDA) of protein for the general population is set at 0.8 g kg–1 per day and the adequate macronutrient distribution range (AMDR) suggests 10–35% of EI coming from protein. Athletes and active individuals have greater protein needs due to the importance of muscle growth and repair (Phillips and Van Loon, 2011) and this includes gymnasts. Protein recommendations have recently focused on optimizing post-exercise muscle protein synthesis (Phillips and Van Loon, 2011). Optimal protein intake may now be expressed relative to a meal based on recent research by Moore et al. (2009) who studied protein intake post-resistance exercise in a dose-response protocol. The optimal intake to maximize muscle fractional synthetic rate after exercise appears to fall within a range of 20–25 g. However, further analyses show that a relative protein intake of 0.25 g kg-1 per meal may be a more practical approach and would also prevent an excess intake in lighter athletes. Using these dynamic recommendations throughout the day, total daily protein intake still ranges from 1.2 to 1.6 g kg–1 per day, which is in line with current recommendations (Phillips and Van Loon, 2011). Thus, for a gymnast weighing 50 kg, a protein intake of 12–15 g spread over two post-exercise snacks and 15–20 g over three meals will equate to ~80 g (1.6 g kg–1) per day. To be specific, a gymnast of that body mass could target 12–15 g of protein post-exercise to support recovery processes before eating lunch or dinner 1–2 hours later. It is likely that nutrient intakes will vary and protein ingestion may exceed 15–20 g for a dinner, especially if a piece of fish, meat, or poultry (25–30 g per 100 g) is combined with carbohydrate-rich sources such as pasta. This should not be of concern, however, and is usually compensated for by breakfast and lunch that are somewhat lower in protein.
The physiological demand of gymnastics is met by both aerobic and anaerobic means. In addition, gymnasts are generally strong as they need to generate a high level of power. Rhythmic gymnasts’ physique, however, tends to be less muscular, as this discipline requires less strength and power compared to artistic gymnasts. Many daily training hours dictate a protein intake similar to strength and power athletes and on the order of 1.6 g kg–1 per day. In addition, dieting athletes or athletes with low EI may minimize loss of lean body mass if there is a relatively high protein intake. Further, adequate protein intake is considered important in low-energy diets due to the thermogenic and satiety-inducing effects.
Protein intake post-exercise has the ability to enhance recovery and repair of muscle tissue. Timing of intake, type of protein, and the addition of other macronutrients such as carbohydrate have all been investigated (Phillips et al., 2011). Using the strategy discussed above (0.25 g kg–1 per meal) should also be beneficial for gymnasts, especially after hard training sessions as protein intake post-exercise enhances the ability to repair and rebuild muscle tissue. A thorough dietary assessment should provide the basis for recommendations given to athletes regarding daily protein requirements.
There are currently neither specific fat recommendations nor an RDA set for the general public or the active individual. The AMDR for fat is 20–35% of EI. Athletes should aim to distribute their fat calories among saturated and unsaturated fat and consume essential fatty acids as recommended by the dietary reference intakes (DRIs). Thus, nutrition education for gymnasts should include the discussion of the type of fats known to provide health and performance benefits. For gymnasts, carbohydrate and protein should be a priority due to the type of activity and appearance; however, fat intake should not be lower than 15–20% of total EI.
Vitamins and minerals
Although vitamins and minerals are not a source of energy, they play a vital role in energy metabolism and overall health. RDAs for vitamins and minerals are defined to prevent nutrient deficiencies and are not determined based on PALs (see “Recommended reading”). In general, athletes have adequate intakes of vitamins and minerals as long as EI is appropriate. However, B vitamins, calcium, vitamin D, iron, some antioxidants (e.g., vitamin C and E, beta carotene, and selenium), zinc, and magnesium can be of concern, especially in gymnasts. Athletes who may present with compromised micronutrient status are those who restrict energy for weight control and/or performance, eliminate one or more food groups due to dietary regimens, restrictions, or fear of calories, or who consume unbalanced diets characterized by low micronutrient density.
Studies including gymnasts show that intake of iron, copper, potassium, calcium, magnesium, zinc, vitamin A, several B vitamins, and vitamin D and E are compromised in these low-energy diets. Actually, some studies report inadequate micronutrient intakes in adolescent gymnasts, despite a relatively high EI. This shows that a well-planned eating (i.e., meals) and fueling (before, during, and after exercise) strategy should be followed when restricting EI to ensure adequate intakes. A gymnasts’ food intake should be rich in nutrients, while low in energy (calories). This requires careful attention when selecting foods and snacks. Finally, most micronutrients are available through dietary sources with the exception of vitamin D, which is best obtained from the sun. Due to the indoor nature of gymnastics, these athletes are at risk for vitamin D deficiency and thus, should be screened for low vitamin D status and adequately treated if deficiency exists.
In summary, nutritional habits of gymnasts are often suboptimal considering their daily training regimen. Sport nutrition professionals should ensure that athletes meet energy requirements. Low EI leads to both acute and chronic adaptations, some of which affect performance, while others may compromise the health and growth of the athlete. Gymnasts should ingest sufficient carbohydrate and protein to ensure daily performance in the gym and rapid recovery post-exercise. Gymnasts should eat a diet rich in nutrients but low in energy density to meet all micronutrient requirements. Finally, gymnastics occurs indoors with little sunlight. All indoor athletes are at greater risk for vitamin D deficiency and should be screened. The next section will focus on the prevalence and risks of disordered eating and eating disorders in the sport of gymnastics.
Dieting and disordered eating in gymnasts
The prepubertal physique confers a performance advantage for gymnasts. Given the biological changes in both male and female athletes during adolescence, it is important to remember that the body in young growing female athletes develops in a direction against the ideal body in gymnastics—being as lean as possible. This may intensify perceptions of self-appearance and performance. Gymnasts start practicing sports by the age of 3 or 4 years of age, and already at age of 5–7 years, girls competing in gymnastics, report greater weight concerns than girls in nonaesthetic sports and nonathletic girls (Davison et al., 2002). As a result, a number of elite female Artistic and Rhythmic Gymnastics teams report the use of self-prescribed diets and pathogenic weight control methods. While more reported in female athletes, inadequate nutritional intake and the use of pathogenic weight control methods are also experienced in some male gymnasts. Female elite gymnasts often display low estradiol levels, hypoleptinemia, reduced body fat mass, insufficient caloric intake, and retarded menarche, while the pubertal development of male gymnasts remains almost unaltered. Long-term inadequate energy and nutrient intakes during the growth period could result in delayed pubertal development and retarded growth. However, there is presently only limited epidemiological evidence of reduced growth or delayed pubertal development in gymnasts. It is difficult to prove that gymnasts experience inadequate growth because of the selection for late-maturing females into the sport. Therefore, the study has yet to be conducted that would provide an estimate of the incidence rate of inadequate growth among female gymnasts.
The consequences of long-term low energy availability (LEA), such as amenorrhea and the imbalance in bone remodeling, are more severe for the adolescent athlete since the lag time of adequate bone formation interferes with reaching a high peak bone mass, adequate stature, and the normal development of the reproductive system. While a long-term process, studies demonstrate a catch-up effect for bone growth and body mass when caloric intake is normalized in young athletes suffering from LEA (Caine et al., 2001).
Although dieting is considered an important risk factor for the development of eating disorders, it is not necessarily dieting per se that triggers disordered eating or eating disorders. Controlled weight loss interventions in elite athletes seem not to increase the risk for disordered eating or eating disorders when guided by a professional sports dietician (Garthe et al., 2011). However, athletes who are still growing should not diet, but be guided how to optimize EI and nutrient intake. Risk factors for eating disorders can be divided into two categories: (1) The pathogenesis of eating disorders is multifactorial with cultural, individual, family, and genetic/biochemical factors all playing a role. (2) There are sports-related factors such as personality factors, experienced pressure to lose weight leading to restricted eating, body dissatisfaction, early start of sport-specific training, injuries, the impact of coaching behavior, and sports regulations (Nattiv et al., 2007). The reason why some athletes, including gymnasts, cross the line from dieting to serious clinical eating disorders is currently unknown. However, it has been reported that dieting and the desire to be leaner to improve performance is associated with the development of eating disorders in adolescent athletes and that regulations, such as in gymnastics, might indirectly increase the risk for eating disorders (Sundgot-Borgen and Garthe, 2011). Prospective controlled studies, examining risk and trigger factors for eating disorders in athletes, do not exist, and thus, the true risk factors for clinical eating disorders in aesthetic sports are not yet known.
Optimizing energy intake and body composition
In order for coaches to adequately perform a supportive function, many need factual information on nutrition and optimal body composition, risks and causes of disordered eating, menstrual (dys)function for females and hormonal changes in males, and psychological factors that both negatively and positively affect health and athletic performance. The authors suggest that all gymnastic disciplines should have position statements with guidelines related to optimizing nutrition and body composition and how to recognize symptoms associated with disordered eating and components of the triad. Dieting and weight issues should never be initiated from the coach, but be presented according to the athletes wish. Coaches should avoid putting pressure and/or telling an athlete to lose weight. Most gymnasts are fit and lean, but often want to reduce weight. In such a case the coach and health care team should motivate the athlete to improve strength and power rather than encouraging weight loss. The focus should be on optimal nutrition and performance enhancement via nondieting strategies including better eating strategies, maintenance of optimal health, as well as improved mental and psychological approaches to training and competition. Health care providers should educate gymnasts and coaches that weight loss does not necessarily lead to improved athletic performance. Furthermore, since athletes are eager to perform, it is important to inform them about the side effects of undereating and inconsistent eating behavior. If the coach is concerned about an athlete’s eating behavior, body image, and/or weight or body fat level, he/she should be referred to a sport dietitian or health care personnel for further evaluation and consultation. However, some gymnasts need to lose weight or change body composition. Therefore, recommendations published by Sundgot-Borgen and Garthe (2011) for healthy changes in body composition or weight are helpful. These are listed below and are specifically adjusted for gymnasts.
Recommendations for weight loss interventions in gymnasts
The body composition goal should be based on objective measurements of body composition. Prior to weight loss intervention, energy and nutrient status should be assessed. Furthermore, questions related to weight history and weight goal, menstrual history and status for females, dietary habits, and feelings about body image, body weight, and food should be included. If a history of disordered eating/eating disorders is present, a more intense and longer follow-up is suggested. Measurements of body composition should be done in private and the results should be explained and discussed with the athlete. The weight loss period should be done during off-season to avoid interference with competitions and sport-specific training loads.
- A 4-day or a 7-day diet record, objective measurements on body mass and fat mass and a blood test should be performed. If the gymnast has a history of amenorrhea or other indicators of low bone mineral density (BMD), an objective measure of BMD is warranted (e.g., DXA). If a blood test indicates any specific micronutrient needs (e.g., iron, vitamin B12, and vitamin D), these vitamins should be provided and biochemical changes monitored during the period. Multivitamin, mineral, and omega-3 fatty acid supplements may be provided during the weight loss period to assure sufficient micronutrient and essential fatty acid intake.
- The gymnast should consume sufficient energy to avoid menstrual irregularities and aim for a gradual weight loss corresponding to ~0.5 kg per week. To induce a weight loss of 0.5 kg per week an energy deficit similar to ~500 kcal per day is needed, but there are individual differences. This can be achieved by reduced EI, increased energy expenditure through cardiovascular conditioning, or a combination of the two.
- A sport dietician who understands the demands of the four disciplines of Olympic gymnastics should plan nutritionally adequate eating strategies tailored to the individual. Throughout this process, the role of overall good nutrition practices in optimizing performance should be emphasized. The plan should contain at least 3–5 g kg-1of carbohydrate, between 1.4 and 2 g kg-1 of protein per day (depending on the athlete’s body composition goals), and provide between 15 and 20% of fat calories (of total EI). The focus should be on foods with low energy content but high nutrient density from a variety of sources, ingested at frequent intervals to support RMR and prolonged satiety, and prevent early fatigue during training. Post-exercise, recovery nutrition should be emphasized through timely (within 30 minutes) ingestion of carbohydrate and protein-containing foods. Foods high in whey protein, such as a flavored milk beverage to optimize muscle repair and recovery may also be recommended. Dairy products are also optimal due to their calcium content. Depending on the athlete and the situation, a well-timed recovery meal within 30 minutes post-exercise may be all that is needed, excluding the immediate recovery strategy in an attempt to reduce extra calories.
- It is important that the weight loss/change in body composition does not compromise gymnastic performance. For most, that means not to lose lean bone mass during weight loss. If that is the case, strength training should be included during the weight loss period. A moderate energy restriction combined with strength training has been shown to alleviate the negative consequences on lean body mass and performance (Garthe et al., 2011). Further, increasing protein intake can also prevent lean body mass.
- After weight loss, body fat percentage should not be lower than 5 for males and 12 for females. It is important to evaluate each gymnast using her own genetic predisposition relative to body fat and weight. Some gymnasts may tolerate a lower percent body fat at no consequence, whereas others may not do as well, meaning they may develop hormonal imbalances and consequential health and performance issues.
- Changes in body composition should be monitored on a regular basis, and athletes should be followed for at least two additional months after the weight or percent body fat goal has been reached just in case any continued or unwarranted losses or weight fluctuations occur.
- “Normal weight” gymnasts under the age of 18 years should be discouraged to lose weight.
There are a limited number of large-scale studies examining energy intake and expenditure in elite gymnasts representing all of the four Olympic disciplines. If practitioners are to tailor recommendations for weight management specific to the disciplines, more data need to be collected relative to both aspects of the energy balance equation in all four disciplines. Studies using the DLW technique should be prioritized in order to reduce the double-sided bias of dietary and PA assessment methods. More data are especially needed for male gymnasts. Large-scale prospective studies are also needed that follow cohorts of gymnasts over time, even into their retired years, to examine changes in eating and dieting behavior and associated performance and health risks. Prospective cohort studies are also suitable for examining risk and trigger factors for eating disorders among gymnasts.
It is particularly important that young gymnasts consume sufficient energy and nutrients to meet the demands of growth, training, competition, and tissue maintenance. Education and counseling regarding factors associated with optimal nutrition and body composition should be provided to both male and female gymnasts, parents, coaches, and health personnel. Circumstances that may adversely affect the gymnast’s short- and long-term health include LEA, disordered eating behaviors, and eating disorders. Some gymnasts cross the line from dieting and use of pathogenic weight loss methods to serious, diagnosable eating disorders. A continuous focus on optimal EI and nutrient intake and the prevention of the female athlete triad is important for all working with young gymnasts.
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