Parallel assessment of nutrition and activity in athletes: Validation against doubly labelled water, 24-h urea excretion, and indirect calorimetry

Validity of Dietary Assessment Methods When Compared to the Method of Doubly Labeled Water: A Systematic Review in Adults

Accuracy in quantifying energy intake (EI) using common dietary assessment methods is crucial for interpreting the relationship between diet and chronic disease. The aim of this systematic review was to evaluate the validity of dietary assessment methods used to estimate the EI of adults in comparison to total energy expenditure (TEE) measured by doubly labeled water (DLW). Articles in English across nine electronic databases, published between 1973 and February 2019 were retrieved. Studies were included if participants were adults (≥18 years) and used the DLW technique to measure TEE compared to self-reported EI. A total of 59 studies were included, with a total of 6,298 free living adults and a mean of 107 participants per study. The majority of studies including 16 studies that included a technology based method reported significant (P < 0.05) under-reporting of EI when compared to TEE, with few over-reporting EI. Misreporting was more frequent among females compared to males within recall based dietary assessment methods. The degree of under-reporting was highly variable within studies using the same method, with 24 h recalls having less variation and degree of under-reporting compared to other methods.

Nutrition Status of Young Elite Female German Football Players

PURPOSE

To investigate energy intake, energy expenditure, and the nutritional status of young female elite football players using 7-day food and activity records and blood parameters.

METHODS

A total of 56 female elite football players [14.8 (0.7) y] completed the requested food and activity protocols. Misreporting was assessed by the ratio of energy intake to energy expenditure. The food records were analyzed concerning energy and macronutrient and micronutrient intakes, and energy expenditure was calculated using predictive equations. Hematological data and 25-hydroxyvitamin D serum concentrations were determined.

RESULTS

Mean energy intake was 2262 (368) kcal/d [40.5 (7.0) kcal/kg/d] and estimated EE averaged 2403 (195) kcal/d. Fifty-three percent of the players exhibited an energy availability <30 kcal/kg lean body mass; 31% of the athletes consumed <5 g/kg carbohydrates and 34% consumed <1.2 g/kg proteins. A large proportion of players (%) had intakes below the recommended daily allowance of folate (75%), vitamin D (100%), iron (69%), and calcium (59%). Ferritin and 25-hydroxyvitamin D serum levels were below the recommendations of 59% and 38%, respectively.

CONCLUSIONS

A remarkable number of players failed to meet the energy balance and the recommended carbohydrate and protein intakes. Low iron and 25-hydroxyvitamin D serum levels were observed showing a suboptimal nutrition status of some young female football players. As a consequence, strategies have to be developed for a better information and application of sport nutrition practice among young female football players.

Validity of Dietary Assessment in Athletes: A Systematic Review

Dietary assessment methods that are recognized as appropriate for the general population are usually applied in a similar manner to athletes, despite the knowledge that sport-specific factors can complicate assessment and impact accuracy in unique ways. As dietary assessment methods are used extensively within the field of sports nutrition, there is concern the validity of methodologies have not undergone more rigorous evaluation in this unique population sub-group. The purpose of this systematic review was to compare two or more methods of dietary assessment, including dietary intake measured against biomarkers or reference measures of energy expenditure, in athletes. Six electronic databases were searched for English-language, full-text articles published from January 1980 until June 2016. The search strategy combined the following keywords: diet, nutrition assessment, athlete, and validity; where the following outcomes are reported but not limited to: energy intake, macro and/or micronutrient intake, food intake, nutritional adequacy, diet quality, or nutritional status. Meta-analysis was performed on studies with sufficient methodological similarity, with between-group standardized mean differences (or effect size) and 95% confidence intervals (CI) being calculated. Of the 1624 studies identified, 18 were eligible for inclusion. Studies comparing self-reported energy intake (EI) to energy expenditure assessed via doubly labelled water were grouped for comparison (n = 11) and demonstrated mean EI was under-estimated by 19% (-2793 ± 1134 kJ/day). Meta-analysis revealed a large pooled effect size of -1.006 (95% CI: -1.3 to -0.7; p < 0.001). The remaining studies (n = 7) compared a new dietary tool or instrument to a reference method(s) (e.g., food record, 24-h dietary recall, biomarker) as part of a validation study. This systematic review revealed there are limited robust studies evaluating dietary assessment methods in athletes. Existing literature demonstrates the substantial variability between methods, with under- and misreporting of intake being frequently observed. There is a clear need for careful validation of dietary assessment methods, including emerging technical innovations, among athlete populations.

Monitoring Energy Expenditure Using a Multi-Sensor Device-Applications and Limitations of the SenseWear Armband in Athletic Populations

In order to monitor their energy requirements, athletes may desire to assess energy expenditure (EE) during training and competition. Recent technological advances and increased customer interest have created a market for wearable devices that measure physiological variables and bodily movement over prolonged time periods and convert this information into EE data. This mini-review provides an overview of the applicability of the SenseWear armband (SWA), which combines accelerometry with measurements of heat production and skin conductivity, to measure total daily energy expenditure (TDEE) and its components such as exercise energy expenditure (ExEE) in athletic populations. While the SWA has been shown to provide valid estimates of EE in the general population, validation studies in athletic populations indicate a tendency toward underestimation of ExEE particularly during high-intensity exercise (>10 METs) with an increasing underestimation as exercise intensity increases. Although limited information is available on the accuracy of the SWA during resistance exercise, high-intensity interval exercise, or mixed exercise forms, there seems to be a similar trend of underestimating high levels of ExEE. The SWA, however, is capable of detecting movement patterns and metabolic measurements even at high exercise intensities, suggesting that underestimation may result from limitations in the proprietary algorithms. In addition, the SWA has been used in the assessment of sleep quantity and quality as well as non-exercise activity thermogenesis. Overall, the SWA provides viable information and remains to be used in various clinical and athletic settings, despite the termination of its commercial sale.

Prediction of human dietary δ15N intake from standardised food records: validity and precision of single meal and 24-h diet data

Natural stable isotope ratios (δ¹⁵N) of humans can be used for nutritional analyses and dietary reconstruction of modern and historic individuals and populations. Information about an individual's metabolic state can be obtained by comparison of tissue and dietary δ¹⁵N. Different methods have been used to estimate dietary δ¹⁵N in the past; however, the validity of such predictions has not been compared to experimental values. For a total of 56 meals and 21 samples of 24-h diets, predicted and experimental δ¹⁵N values were compared. The δ¹⁵N values were predicted from self-recorded food intake and compared with experimental δ¹⁵N values. Predicted and experimental δ¹⁵N values were in good agreement for meals and preparations (r = 0.89, p < .001) as well as for the 24-h diets (r = 0.76, p < .001). Dietary δ¹⁵N was mainly determined by the amount of fish, whereas the contribution of meat to dietary δ¹⁵N values was less pronounced. Prediction of human dietary δ¹⁵N values using standardised food records and representative δ¹⁵N data sets yields reliable data for dietary δ¹⁵N intake. A differentiated analysis of the primary protein sources is necessary when relating the proportion of animal-derived protein in the diet by δ¹⁵N analysis.

Do we excrete what we eat? Analysis of stable nitrogen isotope ratios of human urinary urea

RATIONALE

Natural stable nitrogen isotope ratios (δ¹⁵ N) are frequently used for the determination of provenance and dietary assessment of recent and ancient humans. Although individual δ¹⁵ N values typically correspond to the dietary δ¹⁵ N composition, they are also affected by metabolic conditions. Preferred matrices for the measurement of human δ¹⁵ N values have been hair, nail or blood. The goal of this study was to validate a novel approach for the assessment of the δ¹⁵ N values from urinary urea, the principal end-product of human N metabolism.

METHODS

The method, which involves the precipitation of urea from urine using xanthydrol, was validated using fortified urea solutions. Intra- and inter-individual variance of the δ¹⁵ N values of urinary urea was determined from samples obtained from multiple human subjects.

RESULTS

Precipitation with xanthydrol did not alter the δ¹⁵ N values of urea. The mean δ¹⁵ N value in urinary urea from human subjects from Germany was +4.4 ± 0.6 ‰, which corresponds to the estimated dietary composition. It falls below previously reported δ¹⁵ N values for human tissue and blood samples. Longitudinal analyses over 7 days illustrate short-time changes linked to varying protein intake.

CONCLUSIONS

Our results indicate that δ¹⁵ N values can be measured reliably from human urine and that the method is suitable to monitor rapid dietary and metabolic changes of an individual. Our findings further confirm that urinary urea is depleted in ¹⁵ N compared with human tissue but within the range of the δ¹⁵ N composition of the diet. Copyright © 2017 John Wiley & Sons, Ltd.

Energy availability discriminates clinical menstrual status in exercising women

Background

Conditions of low energy availability (EA) (<30 kcal/kgLBM) have been associated with suppressed metabolic hormones and reductions in LH pulsatility in previously sedentary women during short-term manipulations of energy intake (EI) and exercise energy expenditure (EEE) in a controlled laboratory setting. The purpose of this study was to examine if EA, defined as EA = (EI-EEE)/kgLBM, is associated with disruptions in ovarian function in exercising women.

Methods

Menstrual status was confirmed with daily measures of urinary reproductive metabolites across 1–3 menstrual cycles or 28-day monitoring periods. EA was calculated for exercise days using EI from 3-day diet logs, EEE from heart-rate monitors and/or exercise logs for a 7-day period, and body composition from DXA. Resting energy expenditure (REE) was measured by indirect calorimetry. Total triiodothyronine (TT₃) was measured from a fasting blood sample.

Results

91 exercising women (23.1 ± 0.5 years) were categorized clinically as either exercising amenorrheic (ExAmen, n = 30), exercising oligomenorrheic (ExOligo, n = 20) or exercising eumenorrheic (ExEumen, n = 41). The eumenorrheic group was further divided into more specific subclinical groups as either exercising ovulatory (ExOv, n = 20), exercising inconsistent (ExIncon, n = 13), or exercising anovulatory (ExAnov, n = 8). An EA threshold of 30 kcal/kgLBM did not distinguish subclinical menstrual status (χ² = 0.557, p = 0.46) nor did EA differ across subclinical disturbance groups (p > 0.05). EA was lower in the ExAmen vs. ExEumen (30.9 ± 2.4 vs. 36.9 ± 1.7 kcal/kgLBM, p = 0.04). The ratio of REE/predicted REE was lower in the ExAmen vs. ExEumen (0.85 ± 0.02 vs. 0.92 ± 0.01, p = 0.001) as was TT₃ (79.6 ± 4.1 vs. 95.3 ± 2.9 ng/mL, p = 0.002).

Conclusions

EA did not differ among subclinical forms of menstrual disturbances in a large sample of exercising women, but EA did discriminate clinical menstrual status, i.e., amenorrhea from eumenorrhea.

2014 Female Athlete Triad Coalition consensus statement on treatment and return to play of the female athlete triad: 1st International Conference held in San Francisco, CA, May 2012, and 2nd International Conference held in Indianapolis, IN, May 2013

The Female Athlete Triad is a medical condition often observed in physically active girls and women, and involves 3 components: (1) low energy availability with or without disordered eating, (2) menstrual dysfunction, and (3) low bone mineral density. Female athletes often present with 1 or more of the 3 Triad components, and an early intervention is essential to prevent its progression to serious endpoints that include clinical eating disorders, amenorrhea, and osteoporosis. This consensus statement represents a set of recommendations developed following the first (San Francisco, California) and second (Indianapolis, Indianna) International Symposia on the Female Athlete Triad. It is intended to provide clinical guidelines for physicians, athletic trainers, and other health care providers for the screening, diagnosis, and treatment of the Female Athlete Triad and to provide clear recommendations for return to play. The 2014 Female Athlete Triad Coalition Consensus Statement on Treatment and Return to Play of the Female Athlete Triad Expert Panel has proposed a risk stratification point system that takes into account magnitude of risk to assist the physician in decision-making regarding sport participation, clearance, and return to play. Guidelines are offered for clearance categories, management by a multidisciplinary team, and implementation of treatment contracts. This consensus paper has been endorsed by The Female Athlete Triad Coalition, an International Consortium of leading Triad researchers, physicians, and other health care professionals, the American College of Sports Medicine, and the American Medical Society for Sports Medicine.

Comparison of self-reported energy availability and metabolic hormones to assess adequacy of dietary energy intake in young elite athletes

Previous intervention studies suggest that leptin, insulin, insulin-like growth factor 1 (IGF-1), and triiodthyronine (T3) are sensitive markers of inadequate energy intake in relation to exercise expenditures. Because of limitations in metabolic hormone measurements, self-reported energy availability (EA) based on food and activity records may present an alternative for characterizing energy status in young athletes. The purpose of the current study was to assess whether self-reported EA is related to leptin, insulin, IGF-1, and T3 in 352 young athletes. Sex, body composition, sport participation, and acute weight changes were considered as confounding variables. Multiple linear regression revealed that EA was negatively associated with leptin (p < 0.05) but not with insulin, IGF-1, or T3. Female athletes with low EA (<30 kcal·kg(-1) fat-free mass (FFM)) had higher leptin concentrations (5.0 ± 4.7 ng·mL(-1)) and more body fat (18.3% ± 5.1%) than did females with normal EA (leptin, 3.1 ± 2.4 ng·mL(-1); body fat, 15.8% ± 4.2%; both, p < 0.001). Athletes reporting acute weight loss (>1 kg·week(-1)) had a lower EA (18.9 ± 7.4 kcal·kg(-1) FFM) than did weight-stable athletes (30.0 ± 11.2 kcal·kg(-1) FFM) or athletes reporting weight gain (>1 kg; 49.7 ± 13.1 kcal·kg(-1) FFM). IGF-1 and T3 were also reduced in athletes who lost weight (p < 0.01). This cross-sectional study reveals a lack of association between self-reported EA and metabolic hormones indicative of energy status in young athletes. Further studies are needed to investigate whether self-reported EA and metabolic hormones are in better agreement when measured repeatedly.

Air-displacement plethysmography pediatric option in 2-6 years old using the four-compartment model as a criterion method

The objective of this study was to determine the accuracy, precision, bias, and reliability of percent fat (%fat) determined by air-displacement plethysmography (ADP) with the pediatric option against the four-compartment model in 31 children (4.1 ± 1.2 years, 103.3 ± 10.2 cm, 17.5 ± 3.4 kg). %Fat was determined by (BOD POD Body Composition System; COSMED USA, Concord, CA) with the pediatric option. Total body water (TBW) was determined by isotope dilution ((2)H(2)O; 0.2 g/kg) while bone mineral was determined by dual-energy X-ray absorptiometry (DXA) (Lunar iDXA v13.31; GE, Fairfield, CT and analyzed using enCore 2010 software). The four-compartment model by Lohman was used as the criterion measure of %fat. The regression for %fat by ADP vs. %fat by the four-compartment model did not deviate from the line of identity where: y = 0.849(x) + 4.291. ADP explained 75.2% of the variance in %fat by the four-compartment model while the standard error of the estimate (SEE) was 2.09 %fat. The Bland-Altman analysis showed %fat by ADP did not exhibit any bias across the range of fatness (r = 0.04; P = 0.81). The reliability of ADP was assessed by the coefficient of variation (CV), within-subject SD, and Cronbach's α. The CV was 3.5%, within-subject SD was 0.9%, and Cronbach's α was 0.95. In conclusion, ADP with the pediatric option is accurate, precise, reliable, and without bias in estimating %fat in children 2-6 years old.

Assessing energy expenditure in male endurance athletes: validity of the SenseWear Armband

PURPOSE

The correct assessment of energy expenditure (EE) in athletes is important to ensure that dietary energy intake is sufficient. In general, athletes are individuals with especially high levels of total EE (TEE) and exercise-related EE (ExEE). The SenseWear Pro3 Armband (SWA) is a multisensor device for the individual assessment of EE, but data on the validity for higher exercise intensities are missing. The aim of the study was to validate the SWA for the assessment of TEE and ExEE in endurance athletes.

METHODS

The SWA was worn by 14 male endurance athletes for 7 d during a regular training period, and TEE was measured in parallel with the doubly labeled water method. Two controlled exercise trials (treadmill running=2.4-4.8 m·s, stationary bicycling=140-380 W) were performed, during which indirect calorimetry was used to assess ExEE.

RESULTS

TEE assessed with the SWA and TEE measured with the doubly labeled water method were significantly correlated (r=0.73, P<0.01), but there were a proportional bias and considerably wide limits of agreement (-1368 to 1238 kcal·d). The error of TEE assessed with the SWA was related to the athletes' individual lactate thresholds (P<0.05). During running and bicycling, ExEE was significantly underestimated for most exercise intensities, and the underestimation increased with exercise intensity (P<0.001).

CONCLUSIONS

According to our results, the SWA does not provide valid results of TEE and ExEE in endurance athletes because of the underestimation of EE at higher exercise intensities. It seems necessary to develop exercise-specific prediction equations to improve EE measurements in athletes.

Iron status in elite young athletes: gender-dependent influences of diet and exercise

Iron depletion seems to occur more frequently among athletes than in the general population and may affect performance capacity. Only little information is available about the prevalence of iron status abnormalities in young elite athletes and whether iron depletion is associated with gender, sport, age or nutrition- and exercise-related factors in this group. Hence, diet, exercise and haematological data from 193 elite athletes (96 males, 97 females; 16.2 ± 2.7 years) from 24 different sports were analyzed retrospectively. Most female athletes failed to meet the recommended daily allowance for iron, even though dietary iron density was higher than in males (5.75 ± 0.78 vs. 6.17 ± 0.98 mg/1,000 kcal; P = 0.001). Iron depletion (serum ferritin < 35 μg/L) occurred in 31% of male and 57% of female athletes (P < 0.001). Low haemoglobin (males: <13 g/dL; females: <12 g/dL) and haematocrit (males: <40%; females: <36%) values were equally prevalent in both genders [haemoglobin: 7.3% (males), 6.2% (females); haematocrit: 13.5% (males); 15.5% (females)]. In females, reduced ferritin levels were associated with a lower dietary iron density (5.9 ± 0.8 vs. 6.6 ± 1.1 mg/1,000 kcal; P = 0.002). Males with iron depletion had a significantly higher estimated energy expenditure (48.7 ± 7.0 vs. 44.4 ± 7.6 kcal/kg/day; P = 0.009).