Authors: Hilary Green1, Ruth Litchfield1, and Ulrike Genschel2

1Food Science and Human Nutrition Department, Iowa State University, Ames, IA
2Department of Statistics, Iowa State University, Ames Iowa

Corresponding Author:
Hilary L. Green, MS, RDN
Department of Food Science and Human Nutrition
2312 Food Sciences Building
536 Farm House Lane
Ames, IA 50011-1061
hilarygreen2014@outlook.com
910-728-7063

Hilary L. Green, MS, RDN is a BS/MS graduate of Iowa State University in Diet and Exercise who performed research under the guidance of Dr. Ruth Litchfield. Her research interests focused on nutrition, inflammation, and the recovery status of division I collegiate female gymnasts.

Ruth Litchfield, PhD, RD, LD is currently a faculty member and Nutrition Extension State Specialist at Iowa State University. Her research interests include nutrition education, health promotion, sports nutrition, educational technology, and school nutrition.

Ulrike Genschel, PhD is an associate professor of statistics. Her research interests are in the areas of statistics education, education research methodology, general statistical methodology, and robust statistics.

Nutrition status of female division I college gymnasts: a descriptive study

ABSTRACT

Research has shown the female athlete triad to be prevalent among aesthetic sports like gymnastics, where decreased energy intake can increase the risk of one or more components of the triad. The importance of nutrition in recovery for elite athletes, including collegiate gymnasts, has also been noted. The purpose of this paper is to examine anthropometric measures and dietary intake during the pre-season and competitive season among division I collegiate female gymnasts. Variable measures were collected in August, December, and April and analyzed using descriptive statistics via SPSS (v25) and SAS (v9.4). Results suggest a decrease in body fat from August to December. Energy, carbohydrate, dietary fiber, potassium, calcium, vitamins (folate, K, D) and choline intakes did not meet current recommendations and diet quality was fair. This study demonstrated suboptimal dietary intake, indicating the need for nutrition interventions to improve nutrient intake and diet quality in collegiate female gymnasts.

Keywords: gymnastics, dietary assessment, energy, macronutrients, micronutrients

INTRODUCTION

The sport of gymnastics emphasizes high lean muscle mass to support powerful vertical movements. Maintaining a desired body image and weight, as well as ability to perform, makes extra fat mass a disadvantage in the sport (28). Athletes with low energy intake are likely deficient in essential macro- and micro-nutrients (4). Notably, among U.S. elite gymnasts, estimated energy intakes were 20% below estimated needs (8). More recently, energy intakes of less than 2,000 kcal/day among female collegiate athletes have been reported (26).

For athletes, health and performance can be impacted by suboptimal dietary intake. More specifically, female athletes participating in aesthetic sports with pressure related to physical appearance, are at increased risk for the female athlete triad (15). The female athlete triad is common among young athletic women and is comprised of three components: abnormal menses, decreased bone mineral density, and low energy availability (15). Low energy availability is postulated to be the etiology of the female athlete triad. Energy availability is defined as dietary energy minus energy expenditure. The proposed causes of low energy availability include disordered eating and insufficient energy intake (15). Insufficient dietary energy may lead to compromised macro- and micro-nutrient intake, further decreasing the ability to synthesize muscle protein and maintain lean muscle mass (12). Ultimately, this poses increased risk for immune suppression, menstrual disturbances, hormonal imbalances, iron-deficiency anemia, and musculoskeletal injuries (4).

Further, metabolic processes, growth, and development require adequate intake of energy, macronutrients, and micronutrients (33). Micronutrient needs can be influenced by the intensity, volume and duration of exercise. The need for micronutrients assisting in the metabolism of energy, carbohydrates, fat, protein, transfer and delivery of oxygen, and reparation of tissues are increased with exercise and subsequent caloric needs (33). Within the general population, deficiencies in calcium, vitamin D, potassium, and iron are common (35). These nutrients are of even greater concern for athletes such as female college gymnasts, where intense training occurs. These nutrients, as well as protein, carbohydrates, vitamin K, vitamin B6, vitamin B12, and folate need to be evaluated (33).

Protein functions to build, maintain, and repair lean muscle mass, while carbohydrates are a major energy source for the brain and muscles (27,34). Gymnastics is a sport that provides mechanical loading via weight-bearing exercise that heightens bone mineralization (9); however, dietary intake of calciumand vitamin D is needed to optimize the bone mineral density and muscle functioning within an athlete. In the United States, several studies have demonstrated the dietary reference intake of vitamin D is usually not met by athletes (11). Potassium is another nutrient of concern in the U.S. where the average intake of 1,755 mg/d (16), is well below the recommended intake of 2600 mg/d. Iron, a nutrient of concern especially for females, functions to carry oxygen to tissues in the body; deficiency can result in anemia with symptoms consisting of fatigue, breathlessness, and heart palpitations. Low levels of vitamin K may be associated with fracture risk, as well as osteoarthritis, a condition that can affect any athlete and any age (30). Lastly, the B-vitamins: vitamin B6, B12, and folate (or folic acid), play critical roles in processes related to physical activity such as coenzyme reactions. Vitamin B6, or otherwise known as pyridoxal 5’-phosphate (PLP) is involved in the breakdown of glycogen, as well as amino acid metabolism. Vitamin B12 assists in recycling folate and plays an important role in methyl transfers between homocysteine to methionine. Folate has similar roles as it is involved in amino acid metabolism and the synthetization of red blood cells and DNA (33).

Dieting and weight loss are common among female athletes competing in aesthetic sports. These methods are not conducive to the overall well-being of an athlete and can cause underperformance (28). Nutrition interventions promoting balanced diets are pertinent to improve the diet quality and physiological functioning of female college athletes in aesthetic sports (26,32). The purpose of this research was to examine diet, energy availability and body composition of division I collegiate female gymnasts throughout the pre-season and competitive season training months.

METHODS

Participants

Division I collegiate female gymnasts at a Midwestern university served as research participants for this study. Potential participants were contacted prior to the training season through email communication. Those interested in participating agreed to attend an informational meeting to explain and receive instructions for completing 5-day food records. Exclusion criteria for participation included the following health conditions: egg allergies, asthma, coronary artery disease, depression, diabetes, hypertension, migraines, cancer or cancer-related complications, or any auto-immune disorder (i.e. rheumatoid arthritis, lupus, inflammatory bowel disease, multiple sclerosis). Thirteen division I collegiate female gymnasts between the ages of 18-22 years old elected to participate in the study throughout the preseason and competitive seasons (August-April). The study was approved by the Institutional Review Board at the University.

Anthropometrics

Weight, body fat percentage (BF %), and fat-free weight (FFW) were collected via BOD POD® measurements for all participants at three time points: baseline (August), post-preseason training (December), and post-competitive season (April). All participants were instructed to fast for a minimum of 10 hours and wear appropriate clothing (i.e. spandex, sports bra, hair cap, no jewelry).

Nutrient Analysis and Energy Availability (EA)

Nutrient analysis of 5-day food records at each time point was conducted using Food Processor Nutrition Analysis Software (ESHA, version 11.3.285, Salem, Oregon). The average of the five days was used for each time point (August, December, April) in statistical analyses. Energy intake values from 5-day food records (August and April time points) were used to calculate energy availability via the equation: [(energy intake [EI] – estimated energy expenditure [EEE])/fat-free weight [FFW]) (29). Energy expenditure was set at zero in August corresponding to baseline, and April as a post-season resting period. Direct energy expenditure measures were not completed for the present study.

Healthy Eating Index (HEI)-2015

HEI scores were calculated using the Automated Self-Administered 24-hour (ASA24-2016) Dietary Assessment Tool (National Cancer Institute, version 2016, Bethesda, MD) (3). HEI-2015 scores were calculated through SAS (version 9.4, SAS Institute Inc., Cary, NC) using the ASA24-2016 output. The simple HEI-2015 scoring algorithm-per day was utilized to calculate scores for each day within each participant’s 5-day food record. The 5-day records were used to calculate an HEI-2015 score at each time point (i.e. August, December, and April) for each participant. The HEI-2015 functions to assign a score from 0 to 100, with 100 indicating compliance with the 2015-2020 Dietary Guidelines (7). According to the HEI grading scale, a diet score of 80 and above is “good’, 51-80 is classified as “needs improvement”, and less than 51 is poor (10).

Statistical Analysis

IBM SPSS Statistics (version 25, IBM, Armonk NY) was used for the calculation of mean ± standard deviation values.

RESULTS

Anthropometrics

The mean age of the 11 participants was 19.6 years old. Anthropometrics including height, weight, Body Mass Index (BMI), body fat percentage (BF%), and Fat-Free Weight (FFW) appear in Table 1. There were no significant changes in weight, BMI, and fat-free weight from August to April. However, mean body fat percentage decreased from August to December, then maintained from December to April.

 Table 1. Anthropometric Characteristics of Gymnast Participants

Collegiate Female Gymnast Participantst
  August (n=11) December (n=10) April (n=11)
Height (cm) 158.2 ± 5.8
Weight (kg) 56.8 ± 5.5 56.6 ± 5.4 56.8 ± 5.7
BMI (kg/m2) 22.7 ± 1.5 22.7 ± 1.5 22.8 ± 1.6
Body Fat (%) 18.1 ± 2.9 15.6 ± 2.8 15.7 ± 4.0
Fat-Free Weight (kg) 46.45 ± 4.38 47.74 ± 4.48 47.86 ± 4.92

t Values are displayed as mean ± standard deviation

Dietary Intake

Mean dietary intakes, including calories, energy availability, protein, fat, carbohydrate, total fiber and the micronutrients: calcium, iron, folic acid, potassium, vitamin D, vitamin K and B vitamins: B6, B12, and choline among the participants appear in Table 2. Results indicated all nutrients decreased with the exception of folic acid and choline between August and December. Recommendations for all dietary intake measures were not met at any time point, except for protein (August and April), vitamin B6 (August, December, and April), and vitamin B12 (August, December, and April). HEI scores were similar to the general population and were relatively unchanged throughout the duration of the study.

Table 2. Dietary Intake of Division I Collegiate Gymnast Participants

Dietary Intake Collegiate Female Gymnast Participantst Current Recommendations
August December April
Calories 1907.46 ± 550.58 1511.38 ± 552.55 1526.85 ± 373.42 3,0001
Energy Availability 40.95 ± 11.23 27.71 ± 9.21 31.99 ± 7.73 ≥ 45 kcal/ kg FFM2
Protein (g) 79.64 ± 30.90 61.56 ± 25.61 71.08 ± 16.18 –
Protein (g/kg) 1.40 ± 0.50 1.12 ± 0.41 1.24 ± 0.26 1.2-2.0 g/kg2
Fat (g) 80.62 ± 35.34 59.28 ± 21.10 56.36 ± 15.67 –
Carbohydrates (g) 223.69 ± 57.50 188.30 ± 79.72 190.72 ± 56.27 –
Carbohydrates (g/kg) 3.94 ± 0.96 3.48 ± 1.34 3.34 ± 0.95 6-10g/kg2
Total Fiber (g) 20.47 ± 10.34 6.82 ± 7.46 6.60 ± 5.56 25 g/d3
Calcium (mg) 733.92 ± 222.13 597.08 ± 261.92 703.08 ± 204.29 1000 mg/d4
Iron (mg) 15.41 ± 10.09 11.21 ± 7.78 9.86 ± 5.52 18 mg/d4
Dietary Folate Equivalents (mcg) 342.32 ± 261.57 260.39 ± 217.13 197.86 ± 137.52 400 mcg/d5
Potassium (mg) 1643.31 ± 611.45 1356.86 ± 878.30 1263.23 ± 613.72 2600 mg/d4
Vitamin D (IU) 72.87 ± 64.62  64.78 ± 40.06 82.90 ± 55.82 600 IU/d4
Vitamin B6 (mg) 1.71 ± 1.05 1.34 ± 1.38 1.30 ± 0.78 1.3 mg4
Vitamin B12 (mcg) 3.29 ± 2.51 2.37 ± 1.90 3.03 ± 2.61 2.4 mcg4
Vitamin K (mcg) 77.80 ± 84.40 49.79 ± 63.32 36.62 ± 24.59 90 mcg4
Choline (mg) 175.75 ± 139.05 212.66 ± 98.70 178.21 ± 140.24 425 mg/d4
Healthy Eating Index 60.45 ± 11.08 60.10 ± 12.03 61.08 ± 8.45 58.06+

t values are displayed as means ± standard deviation; +Average HEI of all Americans
1 Appendix 2: 2015-2020 Dietary Guidelines
2 Thomas et al. 2016
3 Nutrient Recommendations: Dietary Reference Intakes
4 Office of Dietary Supplements
5 CDC
6 HEI Scores for Americans

DISCUSSION

Energy Availability

Low energy availability (EA), one of the potential causes of the female athlete triad, can result from insufficient energy intake. In this study, we found an overall decrease in mean energy intake throughout the pre- and competitive season. Similar findings of decreased energy intake and energy availability among collegiate female athletes has been reported in division I female soccer players as the pre- and competitive season progressed (25). Recommended EA intake is ≥ 45 kcal/kg FFW (4,14,29)after accounting for the energy expended in exercise. Energy expenditure was not captured in this study; however, we were interested in exploring the adequacy of EA assuming no energy expenditure needs. Not surprisingly, EA in this population of collegiate female gymnasts did not meet the recommendation of 45 kcal/kg at any time point. The collegiate gymnast participants in this study had EA values during post-preseason (December) and post-season (April) of approximately 28 and 32 kcal/kg FFW, respectively. Reed and colleagues noted low EA rebounded post-season suggesting this condition may be seasonal, and further, reversible (25). One area of concern is the association between low EA, low bone mineral density, and menstrual dysfunction in the female athlete triad. These complications are more likely when EA is less than 30 kcal/kg FFW per day (14). Results of the current study were near this threshold in August and April, and below the threshold in December. Although an athlete may be striving to achieve a particular body shape via an energy deficit for a competitive advantage, the consequences of this practice can potentially lead to deficits in hydration, glycogen, lean muscle mass, and other physiological issues impairing performance (29). Recommendations by the American College of Sports Medicine suggest energy deficit practices should take place prior to competitive season training, at a slower rate with increased protein intake (29).

Macro and Micro-nutrients

Overall energy intake, as well as several macro- and micronutrients decreased throughout the pre-season and competitive season. A balance of macro- and micro-nutrients is crucial to fuel an athlete’s training and recovery. Fat and carbohydrates decreased throughout the competitive season whereas protein intake remained relatively unchanged. Fat is an essential energy source and there are no specific recommendation amounts for athletes. However, the American College of Sports Medicine (ACSM) notes that fat intake should be dependent upon on both an athlete’s individual level of training and goals for body composition (29). Further, ACSM suggests athletes should follow the current 2015-2020 Dietary Guidelines where less than 10% of energy should be from saturated fat and sources of essential fatty acids should be included within the diet (1,29).

Carbohydrate recommendations suggest moderate-high intensity exercise programs, classified as 1-3 hours/day, require 6-10g/kg/day of nutrient-rich carbohydrates (29). The intensity, time, and amount of exercise are relevant to the amount of carbohydrates needed by an athlete for recovery. In this study, collegiate gymnast participants trained approximately 3-4 hours per day (weight lifting and practice) yet average carbohydrate intake (g/kg/day) at each time point (August: 3.94 ± 0.96 g/kg, December: 3.48 ± 1.34 g/kg, and April: 3.34 ± 0.95 g/kg) did not even approach the ACSM recommendation. Mean total fiber decreased over time and at no point met the recommended daily intake of 25 g/d. This is not a surprising finding as the average intake in American females, ages 19-30 years old, is a mere 14.7g/d according to the latest collected data from What We Eat in America (35).

Current recommendations by the ACSM suggest 1.2-2.0 g/kg/d of dietary protein to support muscle protein synthesis and repair (29). Even higher protein Intakes (2.3 g/kg) may be needed when there is a reduction in energy intake or during short, intense exercise bouts (29). Research has demonstrated higher protein intakes may act as protection to both maintain fat-free mass and promote muscle protein synthesis (29). While this population did not meet the recommended EA, they did maintain their protein intake and met the protein recommendation albeit on the lower end. This may be due to an increased effort to educate the team on having adequate protein post-exercise for muscle gain, maintenance, and recovery by the coaches and sports dietitian through both one-on-one and group nutrition counseling.

Within this collegiate female gymnast population, the additional nutrients of concern, calcium, potassium, iron, and vitamin K, were deficient in comparison to the recommendations. All nutrients demonstrated a trend of having the highest intake before pre-season with a reduction in intake thereafter. The most notable decrease was found in calcium intake at the post-preseason time point (December: 597.08 ± 261.92 mg). Gymnastics provides mechanical loading that increases bone mass but adequate dietary intake of calcium is needed to prevent low bone mineral density and future conditions like osteoporosis. Concomitantly, vitamin D did not even approach the recommendation of 600 IU. Maximization of vitamin D intake is recommended to prevent low bone mineral density, optimize muscle functioning and reduce the inflammatory response (13). The current vitamin D recommendation is for children and adults up to 70 years old (23); specific vitamin D recommendations for athletes have not been fully determined. However, gymnasts train indoor year-round where adequate sun exposure cannot be achieved to acquire vitamin D. Further, recommendations by the Endocrine Society suggests 1,500-2000 IU/day for optimal vitamin D levels (24). Low vitamin D in this study is not a surprising finding as previous research work examining vitamin D intake across several college sports found only a small percentage met the Recommended Dietary Allowance (RDA) (6). Current findings indicate the need for interventions, which likely require vitamin D supplementation.

Vitamin B6 and B12 intake met or exceeded recommendations in the present study. Past research has associated sufficient energy and the consumption of animal products with good vitamin B12 status (33). However, folate intake did not meet the recommended amount of 400 mcg/d at any time point. It is possible that there was a lack of foods with naturally present folate (i.e. vegetables, fruits and fruit juices, nuts, beans, and peas) and/or those fortified with folate (i.e. breakfast cereals) in the diet within the female college gymnasts. This recommendation is particularly important for the prevention of cancer, depression, heart disease, and stroke. In addition, for women at the reproductive age, folate intake has been associated with the prevention of neural tube defects in a child (19).

Choline, a micronutrient similar to the B vitamins, was an additional nutrient of interest. Results of this study demonstrated choline intake (175 – 212 mg/d) was lower than the typical intake among adult females (273 mg/d) and about half the current recommendation (425 mg/d) (18). Dietary choline is a precursor to the neurotransmitter acetylcholine, which functions to relay signals to induce muscular contractions. In addition, dietary choline has been suggested to play a role in reducing the inflammatory response in healthy adults (5). Given the intensity of training and neuromuscular action needed to perform the powerful movements in gymnastics, choline may be of benefit to the population. Though dietary choline intake amongst the participants was lacking, it may have been related to the decreasing energy intake.

HEI-2015

Finally, results of the current study suggest the overall diet quality of division I female gymnasts is similar to that of the general population. The HEI-2015 scores suggest gymnasts’ diet quality (~60) was similar to the mean values for all Americans and adults, ages 18-64 years old (59.0 and 58.0, respectively) (7). Past research by Webber et al examining diet quality demonstrated lower but similar findings amongst a larger group of collegiate athletes (n=138). Average diet quality of participants in this study was 51.2 ± 8.8 (31). Moreover, it is apparent that what may be considered some of the “healthiest” individuals are not aligning with the dietary recommendations (i.e. 2015-2020 Dietary Guidelines for Americans).

Limitations

There were several inherent limitations with this study. First, the small sample size limits the interpretation of the results. The small sample size also leaves room for error due to the inter-individual variability, attrition, and difficulty in generalizing diet quality in the population group. Second, two different nutrient analysis software programs were utilized to examine nutrient intake. It may be prudent to utilize the ASA24-2016 software to assess both dietary intake and corresponding HEI scores. Finally, the use of the 5-day food records can yield confounding results due to it being a self-report measure. Moreover, participants may have over- or under-estimated their dietary intake.

CONCLUSIONS

Our findings within collegiate female gymnasts indicate inadequate energy intake, energy availability, macronutrient, and micronutrient intake. In addition, diet quality via the HEI-2015 was rated as fair. Gymnasts may be perceived as a “healthy” population but results of this study suggest that there is a need for improvements in both nutrition knowledge and dietary intake to ensure adequate physiological and psychological functioning, recovery and successful performance. Avenues to mitigate this issue may be through increased dietary assessments and/or sport nutrition counseling to help collegiate female gymnasts meet the recommendations for energy, macronutrient, and micronutrient intake. Future research should consider investigating a larger sample population, as well as extend to cover the offseason.

APPLICATIONS IN SPORT

Suboptimal energy intake can negatively impact the nutrition status of females in aesthetic sports like gymnastics. Further, the sports medicine team should work to counsel and prevent poor diet quality to promote overall health.

ACKNOWLEDGEMENTS

HG and RL designed, collected, analyzed, and interpreted the data. UG analyzed and interpreted data and providing editing to the manuscript. The data used and/or analyzed during the current study were a part of a larger study. Funding was received from the Iowa Egg Council and Egg Nutrition Center. The study’s sponsor did not participate in designing, conducting, or presenting the study during the publication process. There are no conflicts of interest to declare from the authors.

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