Hattie H Wright

Energy availability in athletes

Abstract This review updates and complements the review of energy balance and body composition in the Proceedings of the 2003 IOC Consensus Conference on Sports Nutrition. It argues that the concept of energy availability is more useful than the concept of energy balance for managing the diets of athletes. It then summarizes recent reports of the existence, aetiologies, and clinical consequences of low energy availability in athletes. This is followed by a review of recent research on the failure of appetite to increase ad libitum energy intake in compensation for exercise energy expenditure. The review closes by summarizing the implications of this research for managing the diets of athletes.

Effects of a multi-micronutrient-fortified beverage, with and without sugar, on growth and cognition in South African schoolchildren: a randomised, double-blind, controlled intervention

Little is known about the effects of combined micronutrient and sugar consumption on growth and cognition. In the present study, we investigated the effects of micronutrients and sugar, alone and in combination, in a beverage on growth and cognition in schoolchildren. In a 2 × 2 factorial design, children (n 414, 6-11 years) were randomly allocated to consume beverages containing (1) micronutrients with sugar, (2) micronutrients with a non-nutritive sweetener, (3) no micronutrients with sugar or (4) no micronutrients with a non-nutritive sweetener for 8.5 months. Growth was assessed and cognition was tested using the Kaufman Assessment Battery for Children version II (KABC-II) subtests and the Hopkins Verbal Learning Test (HVLT). Micronutrients decreased the OR for Fe deficiency at the endpoint (OR 0.19; 95% CI 0.07, 0.53). Micronutrients increased KABC Atlantis (intervention effect: 0.76; 95% CI 0.10, 1.42) and HVLT Discrimination Index (1.00; 95% CI 0.01, 2.00) scores. Sugar increased KABC Atlantis (0.71; 95% CI 0.05, 1.37) and Rover (0.72; 95% CI 0.08, 1.35) scores and HVLT Recall 3 (0.94; 95% CI 0.15, 1.72). Significant micronutrient × sugar interaction effects on the Atlantis, Number recall, Rover and Discrimination Index scores indicated that micronutrients and sugar in combination attenuated the beneficial effects of micronutrients or sugar alone. Micronutrients or sugar alone had a lowering effect on weight-for-age z-scores relative to controls (micronutrients - 0.08; 95% CI - 0.15, - 0.01; sugar - 0.07; 95% CI - 0.14, - 0.002), but in combination, this effect was attenuated. The beverages with micronutrients or added sugar alone had a beneficial effect on cognition, which was attenuated when provided in combination.

Dietary assessment methodology for adolescents: a review of reproducibility and validation studies

Abstract Aim: The aim of this review is to explore the validity and/or reproducibility of dietary assessment methods used to assess food and nutrient intakes of adolescents. Method: A detailed literature search was undertaken to trace articles reporting on the validity and/or reproducibility of food records, food frequency questionnaires (FFQs) and 24-hour recalls for the dietary assessment of adolescents, especially among South Africans, in the following databases: Medline, Science Direct, Academic Search Premier, Health Source, PubMed and the South African e-publications database (SAE). Original studies published between 1990 and 2009, and relevant original articles published before 1990, were included. Of these, only three were South African-based studies reporting testing for reproducibility and/or validity. Results: Results indicated that adolescents comply better with estimated food records than with weighed food records. However, energy intake was underestimated in adolescents (by 18–42%) when using food record methods. The relative validity of FFQs among adolescents was moderate, with correlation coefficients of > 0.3 for most measured nutrients and food items. Reproducibility was fair to good among female adolescents (0.3–0.83) for most nutrients and foods, but was lower in a South African Tswana-speaking group. The 24-hour recall method showed the least over- and underestimation of all the reviewed methods. When comparing the 24-hour recall method to an observed intake method among adolescents, < 11% underestimation of energy intake was found, while < 4% underestimation was found when the 24-hour recall method was tested against the doubly labelled water method. Conclusion: Based on these outcomes it was concluded that FFQs and 24-hour recalls are valid and reproducible dietary assessment methods that can be used when collecting dietary data from adolescents. Factors to consider when choosing the best suitable method should include the gender and ethnicity of the population as well as the time frame for the collection of dietary data.

Lean mass appears to be more strongly associated with bone health than fat mass in urban black South African women

ObjectivesTo examine the association between body composition (fat mass, lean mass and body mass index, BMI) and bone health (bone mineral density, BMD and fracture risk) in urban black South African women.DesignA cross sectional study examining associations between body composition, dietary intake (food frequency questionnaire), habitual physical activity (Activity energy expenditure (AEE) measured using an accelerometer with combined heart rate monitor and physical activity questionnaire) and bone health (BMD using dual-energy X ray absorptiometry, DXA and fracture risk).SettingUrban community dwellers from Ikageng in the North-West Province of South Africa.ParticipantsOne hundred and eighty nine (189) healthy postmenopausal women aged ≥43 years.ResultsFat mass and lean mass were significantly associated with BMD and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = −0.19 p =0.04) when both lean and fat mass were in the same model.ConclusionLean mass and fat mass were positively associated with femoral neck, spine and hip BMDs and negatively associated with fracture risk in urban black South African women. Our finding suggests that increasing lean mass rather than fat mass is beneficial to bone health. Our study emphasises the importance of positive lifestyle changes, intake of calcium from dairy and adequate weight to maintain and improve bone health of postmenopausal women.

The glycaemic index and sports nutrition

Carbohydrate (CHO) is the main fuel for exercising muscles, therefore the amount, timing and type of CHO food ingested is an important part of an athlete’s daily dietary intake. The amount and timing of CHO ingestion has been investigated extensively. It has been suggested that the glycaemic index (GI) of CHO foods influences CHO availability during exercise and the rate of glycogen synthesis post-exercise. Although low-GI (LGI) CHO foods are mostly recommended for the pre-exercise meal, ingesting high-GI (HGI) CHO foods pre-exercise mostly does not result in hypoglycaemia in healthy individuals during exercise. HGI and LGI CHO foods yield similar results in terms of exercise performance and perceived rate of exertion. HGI and moderate GI (MGI) CHO foods are recommended during exercise. However, fructose in high concentrations is not recommended owing to increased risk of gastrointestinal distress. LGI CHO foods are not recommended during a short recovery period (< 6 hours) because of their slow rate of absorption and indigestible CHO, which seems to be a poor substrate for glycogen synthesis.

The female athlete triad in student track and field athletes

Abstract Objectives: To explore the female athlete triad components in university track and field athletes, as well as calculate estimated energy availability. Design: Cross-sectional descriptive study design. Setting and subjects: Sixteen volunteer, white, female track and field athletes were recruited from North-West University. Outcome measures: Athletes completed a demographic, health and sport questionnaire; pathogenic body weight control questionnaire; menstrual history questionnaire; four 24-hour dietary recalls and one three-day diet and exercise record form. Body composition and bone mineral density (BMD) were assessed with dual energy X-ray absorptiometry. The bulimia, drive for thinness and body dissatisfaction subscales of the Eating Disorder Inventory, and the cognitive dietary restraint subscale of the Three-Factor Eating Questionnaire, was used to measure disordered eating behaviour. Estimated energy availability was calculated using a three-day dietary and exercise record form completed by the athlete on three heavy training days. Results: In the total group, 25% had menstrual pattern changes, 62.5% disordered eating behaviour, 73.3% (11/15) low estimated energy availability, and 12.5% reported stress fractures during the past two years. The average estimated energy availability was 18.5 (14.1-40.9) kcal/kg fat-free mass/day. Diet or fat-burning pills were the most popular pathogenic weight-control measures used by 37.5% athletes. Athletes with menstrual pattern changes had lower spine [1.043 (0.975-1.059) vs. 1.166 (1.090-1.234) g/cm2, p-value = 0.043] and femoral neck [0.905 ± 0.045 vs. 1.025 ± 0.027 g/cm2, p-value = 0.042) BMD. Altogether, 87.5% athletes presented with various components of . Conclusion: More than two thirds of this group of student track and field athletes had low estimated energy availability and more than three quarters were classified with various combinations of the components of the female athlete triad.

Socio-Demographic and Lifestyle Factors Predict 5-Year Changes in Adiposity among a Group of Black South African Adults

The rising prevalence of obesity and excessive adiposity are global public health concerns. Understanding determinants of changes in adiposity over time is critical for informing effective evidence-based prevention or treatment. However, limited information is available to achieve this objective. Cultural, demographic, environmental, and behavioral factors including socio-economic status (SES) likely account for obesity development. To this end, we related these variables to anthropometric measures in 1058 black adult Tswana-speaking South Africans who were HIV negative in a prospective study over five years. Body mass index (BMI) and waist circumference increased in both sexes, whereas triceps skinfold thickness remained the same. Over the five years, women moved to higher BMI categories and more were diagnosed with central obesity. Age correlated negatively, whereas SES, physical activity, energy, and fat intake correlated positively with adiposity markers in women. In men, SES, marital status, physical activity, and being urban predicted increases in adiposity. For women, SES and urbanicity increased, whereas menopause and smoking decreased adiposity. Among men, smokers had less change in BMI than those that never smoked over five years. Our findings suggest that interventions, focusing on the urban living, the married and those with the highest SES—the high-risk groups identified herein—are of primary importance to contain morbidity and premature mortality due to obesity in black South Africans.

Association of 25-hydroxyvitamin D and parathyroid hormone with the metabolic syndrome in black South African women

The relationship between 25 hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and metabolic traits appear to differ among ethnicities and may be influenced by obesity. The aim of the study was to examine the association of serum 25(OH)D or PTH with metabolic syndrome (MetS) while controlling for adiposity in black women. Using a cross-sectional study design, 209 urban black women aged ≥ 43 years from the North West Province, South Africa, were included. Multiple regression models were used to explore the relationship between 25(OH)D or PTH and body composition. To explore the association between 25(OH)D or PTH and MetS, a separate variable was created including at least 3 of the MetS criteria, but excluding elevated waist circumference as a diagnostic criterion in a logistic regression model. The majority of the women (69.9%) were overweight or obese and 65.5% of the women had excessive adiposity using the age-specific cut-off points for body fat percentage. All body composition variables were positively associated with PTH, whereas body mass index and waist circumference, but not body fat percentage, had negative associations with 25(OH)D also after adjusting for confounders. Before and after adjusting for age, body fat, habitual physical activity, tobacco use, season of data collection, and estimated glomerular filtration rate, neither 25(OH)D nor PTH showed significant associations with MetS. Although PTH was positively associated and 25(OH)D was negatively associated with adiposity in black women, there was no association between either 25(OH)D or PTH and MetS in this study population, nor did adiposity influence these relationships.

Influence of Race on the Female Athlete Triad: 3373 Board #17 May 31, 8

The Female Athlete Triad (Triad) is a syndrome consisting of three interrelated components: disordered eating (DE), menstrual dysfunction (MD), and low bone mineral density (LB). The Triad is seen in a wide range of female athletes and is a serious medical concern. PURPOSE: To investigate the influence of race and sports participation on the prevalence of the Triad. METHODS: 57 female collegiate athletes (17 black and 40 white, age: 19.7 ± 1.3 years, height: 166.8 ± 7 cm, mass: 65.2 ± 10.2 kg) and 30 sedentary peers (7 black and 23 white, age: 23.5 ± 4.7 years, height: 163.7 ± 6.4 cm, mass: 59.5 ± 7.5 kg) completed questionnaires on demographics, medical history, sports participation and factors relating to the Triad. Bone mineral density was assessed using dual energy X-ray absorptiometry (DXA). Prevalence of the individual Triad components was assessed. RESULTS: The prevalence of DE and MD was significantly greater (p<0.05) in white athletes than in black athletes. In contrast, the prevalence of LB was greater in black athletes than in white athletes. The prevalence of DE, MD, and LB was similar in white athletes and white sedentary (DE: 68% vs. 65%; MD 33% vs. 44%; LB: 22% vs. 15%). There was a trend (p<0.10) for greater prevalence of DE and MD in black sedentary than in black athletes (DE: 57% vs. 18%; MD 43% vs. 6%). The prevalence of LB was similar in black athletes vs. sedentary peers (LB: 47% vs. 29%). CONCLUSION: White female athletes have a higher risk for DE and ME than black female athletes, whereas black female athletes have a greater risk for LB. However, athletes where not at a greater risk for developing any of the three Triad components compared to sedentary peers.