Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance

Energy and macronutrient intake of a female vegan cyclist during an 8-day mountain bike stage race

This report describes the dietary intake of a vegan mountain biker (height, 161 cm; weight, 49.6 kg; body mass index, 19.1 kg/m(2); relative peak power output, 4.6 W/kg) during the Transalp Challenge 2004 (altitude climbed, 22,500 m; total distance, 662 km), illustrating an aggressive dietary strategy that allowed the cyclist to be competitive. She finished the 8-stage event in 42 hours (mixed category, rank 16; 514 minutes behind the winners of this category), cycling with an average heart rate of 79.5% of laboratory-determined maximum, spending 892 minutes and 1627 minutes at intensities below and above 80%, respectively. During racing, the consumption of energy was 69.3 MJ (1.65 MJ/h), 65.76 MJ from carbohydrates (92 g/h), which was 35% of calories and 40% of carbohydrate total intake, and the fluid ingested was 3 L/day (570 mL/h), 55% of the total fluid consumed.

Efeitos do ácido ascórbico nos biomarcadores de estresse oxidativo em nadadores de elite

OBJETIVO: O objetivo do estudo foi verificar os efeitos da oferta de vitamina C através de um suplemento alimentar e dieta rica em ácido ascórbico (AA) no estresse oxidativo induzido pelo exercício. MÉTODOS: A amostra foi composta por 13 nadadores de elite (seis homens e sete mulheres) com idades entre 18 e 26 anos. Os mesmos atletas foram submetidos a sessão de exercício agudo em três fases, com diferentes tratamentos: controle (C), dieta rica em AA (D) e suplemento de AA (S), nas quais amostras de sangue foram colhidas antes, imediatamente após e 24 horas depois do exercício. Para comparação entre as fases e etapas foi utilizado o modelo de regressão linear com efeitos mistos. RESULTADOS: O consumo alimentar habitual de antioxidantes não foi diferente entre as fases, apenas a ingestão de AA foi maior na fase D e S em relação à fase C. O uso de dieta rica em AA favoreceu uma menor peroxidação lipídica, devido aos menores valores de hidroperóxidos lipídicos (FOX), diminuição da peroxidação após exercício, pela diminuição de substâncias reativas ao ácido tiobarbitúrico (TBARS) e aumento dos níveis de vitamina C logo após o exercício. O uso de suplemento de AA também conteve a peroxidação lipídica após exercício e aumentou o poder antioxidante, devido aos maiores níveis de glutationa reduzida (GSH). Sem adição de AA os nadadores tiveram um maior dano hepático, pois apresentaram maiores níveis de transaminase-glutâmico-oxalacética (TGO), menores níveis de antioxidantes (vitamina C e GSH) e aumento do ácido úrico. CONCLUSÃO: Assim, as mudanças observadas com a adição de AA à dieta de nadadores sugerem um importante papel deste micronutriente na defesa contra o estresse oxidativo induzido pelo exercício.

Training table to the battlefield: protein recommendations for warfighters

Warfighters represent a population of athletes for whom routine training and physical expectations for military operations parallel, and very often exceed, those of their civilian counterparts. Like athletes, warfighters require nutrition support to optimize physical condition to maintain training, sustain performance, speed recovery, and prevent injury and illness. Specifically, energy and protein requirements have been tailored for these populations. Like athletes, warfighters consider protein a critical component of their diet and often incorporate protein supplements into daily diet plans. This article highlights sports nutrition principles that target energy and protein needs of athletes, considers the basis of these recommendations in the context of protein supplementation, and asserts that translating these recommendations to the warfighter is appropriate and necessary. The recommended range of protein intake of 1.2-1.8 g · kg (- 1) · d (- 1) can be extended to the warfighter. Because energy balance is pivotal to optimal protein utilization, adequate energy intake or lack thereof such that a state of negative energy balance exists, should be given particular consideration for the warfighter. Routine protein supplementation is recommended to reduce protein breakdown, support protein synthesis, and promote a positive net protein balance throughout various deployment situations and when energy intake is insufficient.

Nutritional practices of athletes in oman: a descriptive study

OBJECTIVE

Adequate dietary intake is crucial for optimum training and performance of athletes. There is almost no available information related to dietary practices among Omani athletes, especially during the competition. This study aimed to assess the nutritional practices (nutritional knowledge, eating habits and daily nutrients intake) among Omani male handball athletes in Muscat city, Oman.

METHODS

This is a cross sectional study including 35 male handball athletes involved in serious training for no less than three years. Data collection was done through personal interviews using a study questionnaire which enlisted questions relating to socio-demographic information, anthropometric measurements and nutritional practices. All the study participants declared no intake of anabolic steroids.

RESULTS

The mean age of the study participants was 27 ± 3 years. Their anthropometric assessment revealed that their mean height was 166 ± 12 cm, mean weight was 75 ± 10 kg, and body mass index was 27 ± 3. Nutritional knowledge analysis revealed that 80% had no nutritional supervision by a nutritionist/dietitian. Their knowledge of nutritional requirements was only 23% correct for total energy intake, 63% for protein intake, 46% for carbohydrate intake, 11% for fat intake and 83% for water intake. Eating habits indicated that 55% had <3 meals/day, 51% had lunch as the principal meal, 51% always added extra salt to their food, 28% took protein supplements on a daily basis, and 51% used pre-competition glycogen load diet. However, none consumed vitamins or mineral supplements. The mean daily caloric intake was 3674 ± 265 kcal/day, which was roughly comprised of 596 ± 66 g carbohydrates, 147 ± 28 g of protein and 78 ± 20 g of total fat.

CONCLUSION

Professional nutritional supervision is needed in order to improve the nutritional knowledge and eating habits of Omani athletes, and therefore improve their athletic performance.

Detecting body fat-A weighty problem BMI versus subcutaneous fat patterns in athletes and non-athletes

We aimed to describe the relationship between BMI and the subcutaneous adipose tissue topography within young athletes and non-athletic controls, to comparatively evaluate the diagnostic powers of subcutaneous adipose tissue thicknesses at different body sites, furthermore to explore appropriate cut-offs to discriminate between athletes and controls. Measurements were determined in 64 males and 42 females, who were subsequently separated into two even groups (athletes and non-athletes). The optical device LIPOMETER was applied at standardised body sites to measure the thickness of subcutaneous adipose tissue layers. To calculate the power of the different body sites and the BMI to discriminate between athletes and non-athletes, receiver operating characteristic curve analysis was performed. In men, the neck (optimal cut-off value 2.3 mm) and trunk (optimal cut-off value 15.5 mm) provided the strongest discrimination power: with 90.6% (58 of 64) of the subjects being correctly classified into athletes or non-athletes. Discrimination power of the BMI values was 64.1% (41 of 64 were correctly classified). In women, the upper back (optimal cut-off value 3.3 mm) and arms (optimal cut-off value 15.9 mm) provided the strongest discrimination power with 88.1% (37 of 42 being correctly classified). When using BMI to discriminate between athletes and non-athletes only 52.4% (22 of 42) were correctly classified. These results suggest that compared to BMI levels, subcutaneous fat patterns are a more accurate way of discriminating between athletes and non-athletes. In particular the neck and the trunk compartment in men and the upper back and arms compartment in women, were the best sites to discriminate between young athletes and non-athletes on the basis of their fat patterns.

Sports drink consumption and diet of children involved in organized sport

BACKGROUND

Organized sport provides one option for children to be physically active. However, there is a paucity of information about the relationship between children's participation in organized sport and their diet, and specifically their sports drink consumption. Therefore, the relationship between sports participation in children and the consumption of sports drinks, sugar-sweetened beverages (SSBs) and other components of diet was examined.

METHODS

A cross-sectional descriptive study was conducted using baseline data from the Action Schools! BC Dissemination study cohort (n = 1421; 9.90 (0.58) y; 736 girls, 685 boys). The differences between the dietary behaviours of children participating in organized sport (sport) versus those that did not participate (non-sport) was examined. A modified Physical Activity Questionnaire for Older Children (PAQ-C) was used to measure physical activity levels and participation in organized sport. A Food Frequency Questionnaire (FFQ) and 24-hour dietary recall were used to assess eating behaviour and macronutrient intake (including protein, fat, and carbohydrate as well as sugar, fibre and total calories). Fruit, vegetable and beverage quantities were hand-tallied from the dietary recall. Fruit, vegetable and beverage frequency was assessed using the FFQ. Analysis of covariance (ANCOVA) was used to analyse differences between groups and a chi-square test of association was use to determine if participation in sport was significantly associated with the proportion of children consuming sports drinks and SSBs, and with gender.

RESULTS

Children involved in sport had a lower body mass index (BMI) and were more physically active than children in the non-sport group (p < 0.01). Only a small number (n = 20/1421) of children consumed sports drinks and no difference in consumption of sports drink between sport and non-sport participants (p > .05) was observed. However, children involved in organized sport consumed more total calories, fat, fibre, fruit, vegetables and non-flavoured milk (p < 0.01) than non-sport children.

CONCLUSIONS

Children involved in organized sport were more physically active, consumed a healthier diet than non-participants and on average had lower BMI's despite consuming more calories. As consumption of sports drinks among this age group was low, this may be an ideal time to begin educating children and their parents about the appropriate consumption of sports drinks and the perils of consuming too many SSBs, specifically.

The role of natural health products (NHPs) in dietetic practice: results from a survey of Canadian dietitians

BACKGROUND

Registered dietitians (RDs) play a key role in disseminating information about nutrition and intervening in nutrition-related disorders in the Canadian context. Natural health products (NHPs) are increasingly associated with nutrition in patient and health professional discussions. For this study, NHPs were divided into three categories: nutritional supplements (NS); functional foods/nutraceuticals (FF/N); and herbal preparations (HP). The objective was to explore RDs' perceptions about their professional roles and responsibilities with respect to three categories of natural health products (NHPs).

METHODS

This research consisted of an on-line survey of registered dietitians (RDs) in Ontario.Surveys were distributed electronically to all practicing RDs in Ontario by the College of Dietitians of Ontario. There were 558 survey respondents, a response rate of 20%.

RESULTS

The vast majority of RDs reported being consulted by clients about all product categories (98% for NS; 94% for FF/N; 91% for HP), with RDs receiving the most frequent questions about NS and the least frequent about HP. 74% of RDs believed that NS are included within the current scope of practice, compared to 59% for FF/N and 14% for HP. Even higher numbers believed that these products should be included: 97% for NS, 91% for FF/N and 47% for HP. RDs who report personally ingesting FF/N and HP were significantly more likely to report that these products should be in the dietetic scope of practice. In contrast, RDs who provide one-on-one counselling services or group-level counselling/workshops were significantly less likely to believe HP should be in the dietetic scope of practice.

CONCLUSIONS

Opinions of RDs indicated that NS and FF/N (and possibly HP) fall within, or should fall within, RDs' scope of practice. Opportunity exists for RDs to undertake a professional role with respect to NHPs. Policy clarification regarding RD roles is needed.

Breakfast consumption and exercise interact to affect cognitive performance and mood later in the day. A randomized controlled trial

The current study assessed the interactive effect of breakfast and exercise on cognition and mood. Twelve active males completed four trials; no breakfast-rest, breakfast-rest, no breakfast-exercise or breakfast-exercise in a randomized, cross-over design. The trials consisted of; breakfast or fast, a 2h rest, exercise (treadmill run) or equivalent rest, a chocolate milk drink, a 90 min rest and an ad libitum lunch. Cognitive performance and mood were recorded frequently throughout each trial. Data was analysed as pre-exercise/rest, during and immediately post exercise/rest and post-drink. No effects were found prior to consumption of the drink. Post-drink, fasting before exercise increased mental fatigue compared to consuming breakfast before exercise and fasting before rest. Tension increased when breakfast was consumed at rest and when exercise was undertaken fasted compared to omitting breakfast before rest. Breakfast before rest decreased rapid visual information processing task speed and impaired Stroop performance. Breakfast omission improved Four Choice Reaction Time performance. To conclude, breakfast before exercise appeared beneficial for post-exercise mood even when a post-exercise snack was consumed. Exercise reversed post-breakfast cognitive impairment in active males.

The influence of commercially-available carbohydrate and carbohydrate-protein supplements on endurance running performance in recreational athletes during a field trial

Background

It is recommended that endurance athletes consume carbohydrate (CHO) supplements, providing 6-8% CHO concentration, during exercise > 60 minutes to improve athletic performance. Recently research has compared carbohydrate-protein (CHO-P) supplementation to the traditionally used CHO supplementation during endurance exercise, following these supplementation recommendations, in controlled settings, but not under simulated applied conditions such as a field trial. Therefore, the purpose of the present investigation was to test CHO and CHO-P supplementation under applied conditions such that commercially-available isocaloric (CHO-P & double-carbohydrate [CHO-CHO]) and isocarbohydrate (CHO-P & CHO) supplements were compared to a placebo (PLA), within an outdoor running field trial > 60 minutes in order to asses their influence on endurance performance.

Methods

Twelve male recreational runners completed four, 19.2 km runs, where they were instructed to run at a pace similar to race pace including a final sprint to the finish, which in this case was the final two laps of the course (1.92 km). Supplementation was provided before the start and in 4 km increments. Performance was measured by time to complete the 19.2 km run and last 1.92 km sprint.

Results

Analyses found no difference between supplements in time to complete the 19.2 km run (PLA = 88.6 ± 11.6 min, CHO = 89.1 ± 11.3 min, CHO-P = 89.1 ± 11.8 min, CHO-CHO = 89.6 ± 11.9 min) or last 1.92 km sprint to the finish (PLA = 8.3 ± 1.2 min, CHO = 8.2 ± 1.2 min, CHO-P = 8.2 ± 1.2 min, CHO-CHO = 8.4 ± 1.5 min).

Conclusions

When following recommendation for supplementation within a field trial, commercially available CHO and CHO-P supplements do not appear to enhance performance in male recreational runners.

Sports nutrition needs: before, during, and after exercise

This article discusses how athletes should properly fuel their bodies before, during, and after exercise to maximize athletic performance. Emphasis is placed on hydration status and glycogen stores being maintained above deficits that negatively affect sport performance. Timing of nutrient intake is as important as composition.

Using a wearable camera to increase the accuracy of dietary analysis

BACKGROUND

Food diaries are commonly used to assess individual dietary intake in both the general and sporting populations. Despite the widespread use of such diaries, evidence suggests that individuals' self-reported energy intake frequently and substantially underestimate true energy intake.

PURPOSE

To examine the use of the Microsoft SenseCam wearable camera to help more accurately report dietary intake within various sporting populations.

METHODS

In 2011, a total of 47 participants were recruited to take part in this study (17 trainee jockeys, 15 elite Gaelic footballers, and 15 healthy physically active university students). Participants wore a SenseCam for 1 day (from morning until night) while simultaneously keeping a 1-day food diary. Comparisons were made between the energy intake reported in the food diary alone and the food diary in conjunction with information gathered from the SenseCam. Data analysis was conducted in 2012.

RESULTS

Mean total calorie intake using diary alone and diary and SenseCam were 2349±827.9 kcals vs 2631±893.4 kcal for the trainee jockeys; 2600±521.9 kcal vs 3191±770.2 kcal for the Gaelic footballers, and 2237±318.5 kcal vs 2487±404.6 kcal for the university students. This represented a difference of 10.7% (p≤0.001); 17.7% (p≤0.001); and 10.1% (p≤0.01) among measurement methods for trainee jockeys, Gaelic footballers, and university students, respectively.

CONCLUSIONS

Results from this first-generation study suggest that a more accurate estimate of total energy intake is provided when combining the use of a conventional food diary and a SenseCam. Additional information on portion size, forgotten foods, leftovers, and brand names can be obtained by using this novel sensing technology in conjunction with the diary, with improved dietary assessment a potential outcome.

Unique aspects of competitive weightlifting: performance, training and physiology

Weightlifting is a dynamic strength and power sport in which two, multijoint, whole-body lifts are performed in competition; the snatch and clean and jerk. During the performance of these lifts, weightlifters have achieved some of the highest absolute and relative peak power outputs reported in the literature. The training structure of competitive weightlifters is characterized by the frequent use of high-intensity resistance exercise movements. Varied coaching and training philosophies currently exist around the world and further research is required to substantiate the best type of training programme for male and female weightlifters of various age groups. As competitive weightlifting is contested over eight male and seven female body weight categories, the anthropometric characteristics of the athletes widely ranges. The body compositions of weightlifters are similar to that of athletes of comparable body mass in other strength and power sports. However, the shorter height and limb lengths of weightlifters provide mechanical advantages when lifting heavy loads by reducing the mechanical torque and the vertical distance that the barbell must be displaced. Furthermore, the shorter body dimensions coincide with a greater mean skeletal muscle cross-sectional area that is advantageous to weightlifting performance. Weightlifting training induces a high metabolic cost. Although dietary records demonstrate that weightlifters typically meet their required daily energy intake, weightlifters have been shown to over consume protein and fat at the expense of adequate carbohydrate. The resulting macronutrient imbalance may not yield optimal performance gains. Cross-sectional data suggest that weightlifting training induces type IIX to IIA fibre-type transformation. Furthermore, weightlifters exhibit hypertrophy of type II fibres that is advantageous to weightlifting performance and maximal force production. As such, the isometric peak force and contractile rate of force development of weightlifters is ~15-20% and ~13-16% greater, respectively, than in other strength and power athletes. In addition, weightlifting training has been shown to reduce the typical sex-related difference in the expression of neuromuscular strength and power. However, this apparent sex-related difference appears to be augmented with increasing adult age demonstrating that women undergo a greater age-related decline in muscle shortening velocity and peak power when compared with men. Weightlifting training and competition has been shown to induce significant structural and functional adaptations of the cardiovascular system. The collective evidence shows that these adaptations are physiological as opposed to pathological. Finally, the acute exercise-induced testosterone, cortisol and growth hormone responses of weightlifters have similarities to that of following conventional strength and hypertrophy protocols involving large muscle mass exercises. The routine assessment of the basal testosterone : cortisol ratio may be beneficial when attempting to quantify the adaptive responses to weightlifting training. As competitive weightlifting is becoming increasingly popular around the world, further research addressing the physiological responses and adaptations of female weightlifters and younger (i.e. ≤17 years of age) and older (i.e. ≥35 years of age) weightlifters of both sexes is required.

Post-prandial carbohydrate ingestion during 1-h of moderate-intensity, intermittent cycling does not improve mood, perceived exertion, or subsequent power output in recreationally-active exercisers

Background

This study compared the effects of ingesting water (W), a flavored carbohydrate-electrolyte (CE) or a flavored non-caloric electrolyte (NCE) beverage on mood, ratings of perceived exertion (RPE), and sprint power during cycling in recreational exercisers.

Methods

Men (n = 23) and women (n = 13) consumed a 24–h standardized diet and reported 2–4 h post-prandial for all test sessions. After a familiarization session, participants completed 50 min of stationary cycling in a warm environment (wet bulb globe temperature = 25.0°C) at ~ 60-65% of heart rate reserve (146 ± 4 bpm) interspersed with 5 rest periods of 2 min each. During exercise, participants consumed W, CE, or NCE, served in a counterbalanced cross-over design. Beverage volume was served in 3 aliquots equaling each individual’s sweat losses (mean 847 ± 368 mL) during the familiarization session. Profiles of Mood States questionnaires (POMS) were administered and blood glucose levels were determined pre- and post- sub-maximal cycling. Following sub-maximal exercise, participants completed 3 30–s Wingate anaerobic tests (W_AnT) with 2.5 min rest between tests to assess performance.

Results

Blood glucose was higher (p <  0.05) after 50 min of submaximal cycling just prior to the W_AnT for CE (6.1 ± 1.7 mmol/L) compared to W (4.9 ± 1.5 mmol/L) and NCE (4.6 ± 1.2 mmol/L). Nonetheless, there were no differences among treatments in peak (642 ± 153, 635 ± 143, 650 ± 141 watts for W, NCE, and CE, respectively; p  =  0.44) or mean (455 ± 100, 458 ± 95, 454 ± 95 watts for W, NCE, and CE, respectively; p = 0.62) power for the first W_AnT or mean (414 ± 92, 425 ± 85, 423 ± 82 watts, respectively; p = 0.13) power output averaged across all 3 W_AnT. Likewise, RPE during submaximal exercise, session RPE, and fatigue and vigor assessed by POMS did not differ among beverage treatments (p > 0.05).

Conclusions

Carbohydrate ingestion consumed by recreational exercisers during a 1–h, moderate-intensity aerobic workout did not alter mood or perceived exertion, nor did it affect subsequent anaerobic performance under the conditions of this study. Drinking caloric sport beverages does not benefit recreational exercisers in a non-fasted state.

Dietary intakes and eating habits of college athletes: are female college athletes following the current sports nutrition standards?

OBJECTIVE

The objective of this study was to assess dietary intakes and eating habits of female college athletes and compared them with the minimum sports nutrition standards.

PARTICIPANTS

Data were obtained from 52 female college athletes from a National Collegiate Athletic Association (NCAA) Division I university between January 2009 and May 2010.

METHODS

Participants completed anthropometric measurements and dietary assessment using a 3-day food record, a 24-hour recall, and a nutrition questionnaire.

RESULTS

t tests indicated the energy and carbohydrate intakes were below the minimum recommended amount (p<.001), with only 9% of the participants meeting their energy needs. Seventy-five percent of the participants failed to consume the minimum amount of carbohydrates that is required to support training. The majority of the participants reported no regular breakfast, 36% consumed<5 meals/day, and only 16% monitored their hydration status.

CONCLUSIONS

Effective nutrition interventions are needed to improve dietary intakes and eating habits of female college athletes.

Bone mineral density in elite adolescent female figure skaters

Abstract

Elite adolescent figure skaters must accommodate both the physical demands of competitive training and the accelerated rate of bone growth that is associated with adolescence, in this sport that emphasizes leanness. Although, these athletes apparently have sufficient osteogenic stimuli to mitigate the effects of possible low energy availability on bone health, the extent or magnitude of bone accrual also varies with training effects, which differ among skater disciplines.

Purpose

We studied differences in total and regional bone mineral density in 36 nationally ranked skaters among 3 skater disciplines: single, pairs, and dancers.

Methods

Bone mineral density (BMD) of the total body and its regions was measured by dual energy x-ray absorptiometry (DXA). Values for total body, spine, pelvis and leg were entered into a statistical mixed regression model to identify the effect of skater discipline on bone mineralization while controlling for energy, vitamin D, and calcium intake.

Results

The skaters had a mean body mass index of 19.8 ± 2.1 and % fat mass of 19.2 ± 5.8. After controlling for dietary intakes of energy, calcium, and vitamin D, there was a significant relationship between skater discipline and BMD (p = 0.002), with single skaters having greater BMD in the total body, legs, and pelvis than ice dancers (p < 0.001). Pair skaters had greater pelvic BMD than ice dancers (p = 0.001).

Conclusions

Single and pair skaters have greater BMD than ice dancers. The osteogenic effect of physical training is most apparent in single skaters, particularly in the bone loading sites of the leg and pelvis.

A diet following Finnish nutrition recommendations does not contribute to the current epidemic of obesity

Objective

Recently, the general public opinion is that nutritional recommendations promote obesity rather than prevent it. We created the Recommended Finnish Diet Score (RFDS) that illustrates the Finnish nutrition recommendations and assessed whether this score is associated with BMI, waist circumference (WC) and body fat percentage (BF%).

Design

Cross-sectional study included two phases of the National FINRISK 2007 Study. Diet was assessed using a validated FFQ. Height, weight, WC and BF% were measured, and BMI values were calculated. The RFDS was developed based on the national nutrition recommendations.

Setting

A large representative sample of the Finnish population.

Subjects

Men (n2190) and women (n2530) aged 25–74 years.

Results

The RFDS was inversely associated with WC in men (OR = 0·48, 95 % CI 0·28, 0·81,P< 0·05) and BF% in both men (OR = 0·44, 95 % CI 0·24, 0·82,P-trend < 0·05) and women (OR = 0·63, 95 % CI 0·37, 1·08,P-trend < 0·05). The inverse association of RFDS and BF% appeared stronger among older age groups (men: OR = 0·21 CI 0·07, 0·64,P-trend < 0·01; women: OR = 0·56, 95 % CI 0·25, 1·27,P-trend < 0·05) and among women with normal BMI (OR = 0·62, 95 % CI 0·36, 1·09,P-trend < 0·05). The RFDS was not associated with BMI.

Conclusions

A diet following nutrition recommendations is likely to help to maintain normal WC and BF%. These findings could be useful for dietary counselling and the prevention of obesity.

Eating attitudes and food intakes of elite adolescent female figure skaters: a cross sectional study

BACKGROUND

Elite adolescent female figure skaters compete in an aesthetic-based sport that values thin builds and lithe figures. To conform to the sport's physical requirements, skaters may alter their eating patterns in unhealthful directions. This study assesses the eating attitudes and dietary intakes of elite adolescent female figure skaters to assess the potential nutritional risks among them.

METHODS

Thirty-six elite competitive adolescent female figure skaters (mean age 16 ± 2.5 SD years) completed self-administered three-day records of dietary intake and simultaneous physical activity records during training season. Two months later, they attended a national training camp during which they completed the Eating Attitudes Test (EAT-40), provided fasting blood samples, and had heights and weights measured.

RESULTS

Participants' mean body mass index (BMI) was 19.8 ± 2.1 SD. Their BMIs were within the normal range, and the majority (70%) did not report a history of recent weight loss. The mean EAT-40 score was normal (19.5 ± 13.5 SD) and below the cut-off score of 30 that indicates clinically significant eating pathology. However, one-quarter of the skaters had EAT-40 scores above 30. The skaters reported a mean energy intake of 1491 ± 471 SD kcal/day (31 ± 10 SD kcal/kg), with 61.6% of calories from carbohydrate, 14.6% from protein, and 23.7% from fat. Their reported dietary intakes were high in carbohydrates but low in total energy, fat, and bone-building nutrients.

CONCLUSIONS

Although these highly active young women compete in a sport that prizes leanness, they had appropriate weights. The athletes reported dietary intakes that were far below estimated energy needs and were at moderate risk of disordered eating. Anticipatory guidance is warranted to improve their dietary intakes, particularly of bone-building nutrients.

Half-marathon and full-marathon runners' hydration practices and perceptions

CONTEXT

The behaviors and beliefs of recreational runners with regard to hydration maintenance are not well elucidated.

OBJECTIVE

To examine which beverages runners choose to drink and why, negative performance and health experiences related to dehydration, and methods used to assess hydration status.

DESIGN

Cross-sectional study.

SETTING

Marathon registration site.

PATIENTS OR OTHER PARTICIPANTS

Men (n = 146) and women (n = 130) (age = 38.3 ± 11.3 years) registered for the 2010 Little Rock Half-Marathon or Full Marathon.

INTERVENTION(S)

A 23-item questionnaire was administered to runners when they picked up their race timing chips.

MAIN OUTCOME MEASURE(S)

Runners were separated into tertiles (Low, Mod, High) based on z scores derived from training volume, expected performance, and running experience. We used a 100-mm visual analog scale with anchors of 0 (never) and 100 (always). Total sample responses and comparisons between tertile groups for questionnaire items are presented.

RESULTS

The High group (58±31) reported greater consumption of sport beverages in exercise environments than the Low (42 ± 35 mm) and Mod (39 ± 32 mm) groups (P < .05) and perceived sport beverages to be superior to water in meeting hydration needs (P < .05) and improving performance during runs greater than 1 hour (P < .05). Seventy percent of runners experienced 1 or more incidents in which they believed dehydration resulted in a major performance decrement, and 45% perceived dehydration to have resulted in adverse health effects. Twenty percent of runners reported monitoring their hydration status. Urine color was the method most often reported (7%), whereas only 2% reported measuring changes in body weight.

CONCLUSIONS

Greater attention should be paid to informing runners of valid techniques to monitor hydration status and developing an appropriate individualized hydration strategy.

Body Composition and Dietary Intake of Elite Cross-country Skiers Members of the Greek National Team

PURPOSE

To assess the anthropometric characteristics and dietary intake of the Greek national cross-country skiing team.

METHODS

Thirty-three athletes (10 females aged 20 ± 5 years; 23 males aged 20 ± 6 years old) participated in the study. All athletes were members of the Greek national ski team, and they had been selected to take part in the Winter Olympics, World Ski Championships, European Ski Championships or other international events, according to their performance. Body composition was estimated by bioelectrical impedance (BIA) and skinfold thickness. The athletes recorded their physical activity and dietary intake for 3 training days, and on a competition day.

RESULTS

The female skiers had 14.2±1.9% body fat, the men 11.0±1.5% body fat. Female athletes consumed a diet of 1988±319 Kcal during training days and 2011±330 Kcal during competition days. Male athletes consumed 2255±790 Kcal and 2125±639 Kcal respectively. These values are below those recommended for highly active people. During the training period, carbohydrate, fat and protein contributed to 44.5±7.1%, 39.2±5.3% and 16.1±3.7% of the total energy intake (EI) respectively for the males, and to 52.8±5.6%, 33.0±3.7% and 14.3±2.5% of the EI of the women. Between training and competition days, men demonstrated an increased carbohydrate and reduced fat consumption when competing (P<0.001 for both). Women, on the other hand, consumed more carbohydrate and less protein during competition days (P<0.05 for both). Protein intake was within the recommended range for both males and females, but fat exceeded the recommended values and was consumed at the expense of carbohydrate. Vitamins B(12), D, E and K, biotin, folate, Ca, Mg, K, I were inadequately consumed (below the RDA) by both women and men, while the women also exhibited inadequate intakes of iron and the men of manganese.

CONCLUSIONS

The inadequate energy and nutrient intake in the Greek national cross-country ski team could put the athletes at risk of nutritional deficiencies, and possibly compromise their athletic performance.

Influence of body mass loss and myoglobinuria on the development of muscle fatigue after a marathon in a warm environment

The aim of this study was to determine the changes in body mass and myoglobinuria concentration in recreational runners during a marathon in a warm environment, and the relation of these changes to muscle fatigue. We recruited 138 amateur runners (114 men and 24 women) for the study. Before the race, leg muscle power output was measured during a countermovement jump on a force platform, body weight was measured, and a urine sample was obtained. Within 3 min of race completion (28 °C; 46% relative humidity), the runners repeated the countermovement jump, body weight was measured again, and a second urine sample was obtained. Myoglobin concentration was determined in the urine samples. After the race, mean body mass reduction was 2.2% ± 1.2%. Fifty-five runners (40% of the total) reduced their body mass by less than 2%, and 10 runners (7.2%) reduced their body mass by more than 4%. Only 3 runners increased their body mass after the marathon. Mean leg muscle power reduction was 16% ± 10%. Twenty-four runners reduced their muscle power by over 30%. No myoglobin was detected in the prerace urine specimens, whereas postrace urinary myoglobin concentration increased to 3.5 ± 9.5 μg·mL(-1) (p < 0.05). Muscle power change after the marathon significantly correlated with postrace urine myoglobin concentration (r = -0.55; p < 0.001), but not with body mass change (r = -0.08; p = 0.35). After a marathon in a warm environment, interindividual variability in body mass change was high, but only 7% of the runners reduced their body mass by more than 4%. The correlation between myoglobinuria and muscle power change suggests that muscle fatigue is associated with muscle breakdown.

Effects of egg white protein supplementation on muscle strength and serum free amino acid concentrations

The aim of this study was to evaluate the effects of egg white protein compared to carbohydrate intake prior to exercise on fat free mass (FFM), one repetition maximum (1RM) muscle strength and blood biochemistry in female athletes. Thirty healthy female collegiate athletes were recruited for this study and matched by sport type, body fat percentage and 1RM leg curl muscle strength. Participants were randomly divided into two groups: protein group (15.0 g egg white protein; 75 kcal) and carbohydrate group (17.5 g maltodextrin, 78 kcal). Supplements were administered daily at the same time in a double-blind manner prior to training during an 8-week period. Measurements were performed before and after the 8-week regimen. The mean dietary energy intake did not change throughout the study period. FFM and 1RM assessments (i.e., leg curl, leg extension, squat, and bench press) increased in both groups. Furthermore, serum urea and serum citrulline levels after the 8-week regimen increased significantly only in the protein group. Our findings indicated that compared to the carbohydrate supplement, the protein supplement was associated with some changes in protein metabolites but not with changes in body composition or muscle strength.

A soy, whey and caseinate blend extends postprandial skeletal muscle protein synthesis in rats

BACKGROUND & AIMS

Blends of dairy and soy protein are used in commercial sports nutrition products; however, no studies have systematically compared blends to isolated protein sources and their effects on muscle protein synthesis (MPS). Dairy whey protein (WP), soy protein isolate (SP), and two blends (Blend 1 and Blend 2) consisting of ratios of 50:25:25 and 25:50:25 for whey:caseinate:soy, respectively, were evaluated for their ability to affect MPS.

METHODS

Male Sprague-Dawley rats were trained to eat 3 meals/day: a 4 g meal at 0700-0720 hours followed by ad lib feeding at 1300-1400 hours and 1800-1900 hours. After ~5 days of training, fasted rats were administered their respective 4 g meal at 0700-0720 hours and an intravenous flooding dose of (2)H5-phenylalanine 10 min prior to euthanasia. Individual rats were euthanized at designated postprandial time points. Blood and gastrocnemius samples were collected and the latter was used to measure mixed muscle protein fractional synthetic rates (FSR).

RESULTS

Plasma leucine concentrations peaked in all groups at 90 min and were still above baseline at 300 min post-meal. FSR tended to increase in all groups post-meal but initial peaks of FSR were different times (45, 90 and 135 min for WP or SP, Blend 1 and Blend 2, respectively). Blend 2 had a significantly higher FSR compared to WP alone at 135 min (P < 0.05).

CONCLUSIONS

Single source proteins and protein blends all enhance skeletal MPS after a meal, however, Blend 2 had a delayed FSR peak which was significantly higher than whey protein at 135 min.

Unique aspects of competitive weightlifting: performance, training and physiology

Weightlifting is a dynamic strength and power sport in which two, multijoint, whole-body lifts are performed in competition; the snatch and clean and jerk. During the performance of these lifts, weightlifters have achieved some of the highest absolute and relative peak power outputs reported in the literature. The training structure of competitive weightlifters is characterized by the frequent use of high-intensity resistance exercise movements. Varied coaching and training philosophies currently exist around the world and further research is required to substantiate the best type of training programme for male and female weightlifters of various age groups. As competitive weightlifting is contested over eight male and seven female body weight categories, the anthropometric characteristics of the athletes widely ranges. The body compositions of weightlifters are similar to that of athletes of comparable body mass in other strength and power sports. However, the shorter height and limb lengths of weightlifters provide mechanical advantages when lifting heavy loads by reducing the mechanical torque and the vertical distance that the barbell must be displaced. Furthermore, the shorter body dimensions coincide with a greater mean skeletal muscle cross-sectional area that is advantageous to weightlifting performance. Weightlifting training induces a high metabolic cost. Although dietary records demonstrate that weightlifters typically meet their required daily energy intake, weightlifters have been shown to over consume protein and fat at the expense of adequate carbohydrate. The resulting macronutrient imbalance may not yield optimal performance gains. Cross-sectional data suggest that weightlifting training induces type IIX to IIA fibre-type transformation. Furthermore, weightlifters exhibit hypertrophy of type II fibres that is advantageous to weightlifting performance and maximal force production. As such, the isometric peak force and contractile rate of force development of weightlifters is ~15-20% and ~13-16% greater, respectively, than in other strength and power athletes. In addition, weightlifting training has been shown to reduce the typical sex-related difference in the expression of neuromuscular strength and power. However, this apparent sex-related difference appears to be augmented with increasing adult age demonstrating that women undergo a greater age-related decline in muscle shortening velocity and peak power when compared with men. Weightlifting training and competition has been shown to induce significant structural and functional adaptations of the cardiovascular system. The collective evidence shows that these adaptations are physiological as opposed to pathological. Finally, the acute exercise-induced testosterone, cortisol and growth hormone responses of weightlifters have similarities to that of following conventional strength and hypertrophy protocols involving large muscle mass exercises. The routine assessment of the basal testosterone : cortisol ratio may be beneficial when attempting to quantify the adaptive responses to weightlifting training. As competitive weightlifting is becoming increasingly popular around the world, further research addressing the physiological responses and adaptations of female weightlifters and younger (i.e. ≤17 years of age) and older (i.e. ≥35 years of age) weightlifters of both sexes is required.

Carbohydrate supplementation increases intramyocellular lipid stores in elite runners

The objective was to determine the effects of carbohydrate (CHO) supplementation on exercise-induced hormone responses and post-training intramyocellular lipid stores (IMCL). Twenty-four elite male athletes (28.0±1.2 years) were randomized to receive CHO (maltodextrin solution) or zero energy placebo solution (control group). The high-intensity running protocol consisted of 10×800 m at 100% of the best 3000-m speed (Vm3 km) and 2×1000 m maximal bouts in the morning and a submaximal 10-km continuous easy running in the afternoon of day 9. IMCL concentrations were assessed by (1)H-MRS before (-day 9) and after training (day 9) in soleus (SO) and tibialis anterior (TA) muscles. Blood hormones were also measured before, during, and post-exercise. The percent change (Δ%) in TA-IMCL was higher in the CHO group (47.9±24.5 IMCL/Cr) than in the control group (-1.7±13.1, respectively) (P=.04). Insulin concentrations were higher in the CHO group post-intermittent running compared to control (P=.02). Circulating levels of free fatty acids and GH were lower in the CHO group (P>.01). The decline in performance in the 2nd 1000-m bout was also attenuated in this group compared to control (P<.001 and P=.0035, respectively). The hormonal milieu (higher insulin and lower GH levels) in the CHO group, together with unchanged free fatty acid levels, probably contributed to the increased IMCL stores. This greater energy storage capacity may have improved post-exercise recovery and thus prevented performance deterioration.

Nutrition education by a registered dietitian improves dietary intake and nutrition knowledge of a NCAA female volleyball team

Eleven female participants from a NCAA Division I volleyball team were evaluated for adequate energy and macronutrient intake during two off-seasons. Total energy and macronutrient intake were assessed by food records and results were compared against estimated needs using the Nelson equation. Dietary intervention was employed regarding the individual dietary needs of each athlete as well as a pre- and post-sports nutrition knowledge survey. Post dietary intervention, total energy, and macronutrient intake improved, as well as a significant improvement in sports nutrition knowledge (p < 0.001). Nutrition education is useful in improving dietary intake and nutrition knowledge of female athletes.

Exploring the feasibility of an academic course that provides nutrition education to collegiate student-athletes

The purpose of this article is to explore the delivery of nutrition education to collegiate student-athletes through an academic course. Existing literature has established the need for nutrition education among collegiate athletes. This article considers the collaboration of the university and the athletic department to better serve this population. Academic wellness courses for student-athletes can be used as models. Finally, benefits, barriers, and proposed course objectives are considered. This report proposes a potential solution to provide consistent, sustainable nutrition education to collegiate student-athletes.

Dietitians use and recommend dietary supplements: report of a survey

BACKGROUND

Dietary supplement use is common in the United States, with more than half of the population using such products. Nutrition authorities consistently advocate a "food first" approach to achieving nutritional adequacy but some, including the Academy of Nutrition and Dietetics (formerly the American Dietetic Association), also recognize that dietary supplements have a role to play in improving nutrient intake to support health and wellness. Surveys show that many health professionals use dietary supplements themselves and also recommend dietary supplements to their patients or clients.

METHODS

As one component of a series of surveys of healthcare professionals (the "Life...supplemented" HCP Impact Studies), 300 registered dietitians were surveyed in 2009 regarding their personal use of dietary supplements and whether they recommend dietary supplements to their clients. Respondents were registered dietitians whose business involved seeing clients in a private practice or at a clinic.

RESULTS

Seventy-four percent of the dietitians surveyed said they were regular users of dietary supplements, while 22% said they used dietary supplements occasionally or seasonally. The primary reasons for using dietary supplements were for bone health (58%), overall health and wellness (53%), and to fill nutrient gaps (42%). When asked if they "ever recommend dietary supplements to clients," 97% of the respondents said they did. The primary reasons were for bone health (70%), to fill nutrient gaps (67%), and overall health and wellness (49%). Eighty-seven percent of the dietitians agreed with the statement, "There are gaps in clients' diets that could effectively be addressed with dietary supplements." The dietitians surveyed said they followed healthy habits including eating a balanced diet (96%), managing stress (92%), visiting their own healthcare professional regularly (86%), exercising regularly (83%), maintaining a healthy weight (80%), and getting a good night's sleep (72%). Nearly all respondents (95%) expressed an interest in continuing education about dietary supplements on a variety of topics.

CONCLUSIONS

Many dietitians, like other health professionals, use dietary supplements regularly as part of their own approach to a healthy diet and lifestyle. They also recommend dietary supplements to their clients or patients, to promote health.

Building a beverage for recovery from endurance activity: a review

Recovery beverages are commonly used by endurance and team-sport athletes during the time between exercise sessions. Practical recommendations on the optimal nutrient composition of these drinks and timing of their consumption are therefore needed. This article summarizes research to date on the use of recovery beverages after aerobic activities and provides the following recommendations for practitioners on the optimal formula and timing of use for endurance and team-sport athletes. Current evidence suggests that, to maximize glycogen resynthesis, athletes should consume about 1.2 g carbohydrate per kilogram body weight as glucose and sucrose immediately after exercise and each hour thereafter for 4-6 hours postexercise. Alternatively, they may consume 0.8 g·kg(-1)·h(-1) in combination with 0.4 g·kg(-1)·h(-1) amino acids or protein. Liquids provide valuable fluids for rehydration, and an ideal recovery beverage should not only contain carbohydrate and protein but also contain electrolytes, including about 0.3-0.7 g sodium·per liter fluid to help restore sodium lost through sweat. Commercial beverages with this type of nutrient composition are effective, and recent work indicates that chocolate milk may be as effective as or superior to these in promoting recovery. Research regarding the effects of specific types of amino acids and antioxidants on recovery is mixed; thus, further investigation is needed before specific recommendations about these nutrients can be made. Future studies that include women and athletes representing a variety of sports, ages, and training levels and that use consistent methodology will lead to a better understanding of the effects of postexercise intake on recovery.

Carbohydrates for Physical Activity

Intake of carbohydrates above the dietary guidelines to support performance of physical activity is common but may be unnecessary and counterproductive. Sports nutrition guidelines have not been designed to incorporate characteristics that may make high carbohydrate consumption a source of metabolic stress that may increase oxidative stress, inflammation, and lipogenesis. This metabolic stress is linked to the physiology underlying the development of insulin resistance, type 2 diabetes mellitus, and cardiovascular diseases. This review describes research-based evidence to aid in bridging the gap between dietary guidelines for overall health and those to support physical activity. Characteristics that increase the likelihood of metabolic stress resulting from carbohydrate intake include overweight and obesity, central/visceral adiposity, older age, sedentary lifestyle, and caloric state. Carbohydrate-based foods that provide the most health benefits are whole grains, beans and legumes, fruits, and vegetables. Carbohydrate-based foods that most readily elicit metabolic stress are those with added sugars and refined grains or that have a high glycemic index. A checklist that incorporates both the number of these characteristics and prevailing guidelines for nutrition and physical activity is presented. This may be useful in determining whether additional carbohydrates are needed to support the physical activity level of the individual.

Comparison of coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men

Background

Sport drinks are ubiquitous within the recreational and competitive fitness and sporting world. Most are manufactured and artificially flavored carbohydrate-electrolyte beverages. Recently, attention has been given to coconut water, a natural alternative to manufactured sport drinks, with initial evidence indicating efficacy with regard to maintaining hydration. We compared coconut water and a carbohydrate-electrolyte sport drink on measures of hydration and physical performance in exercise-trained men.

Methods

Following a 60-minute bout of dehydrating treadmill exercise, 12 exercise-trained men (26.6 ± 5.7 yrs) received bottled water (BW), pure coconut water (VitaCoco^®: CW), coconut water from concentrate (CWC), or a carbohydrate-electrolyte sport drink (SD) [a fluid amount based on body mass loss during the dehydrating exercise] on four occasions (separated by at least 5 days) in a random order, single blind (subject and not investigators), cross-over design. Hydration status (body mass, fluid retention, plasma osmolality, urine specific gravity) and performance (treadmill time to exhaustion; assessed after rehydration) were determined during the recovery period. Subjective measures of thirst, bloatedness, refreshed, stomach upset, and tiredness were also determined using a 5-point visual analog scale.

Results

Subjects lost approximately 1.7 kg (~2% of body mass) during the dehydrating exercise and regained this amount in a relatively similar manner following consumption of all conditions. No differences were noted between coconut water (CW or CWC) and SD for any measures of fluid retention (p > 0.05). Regarding exercise performance, no significant difference (p > 0.05) was noted between BW (11.9 ± 5.9 min), CW (12.3 ± 5.8 min), CWC (11.9 ± 6.0 min), and SD (12.8 ± 4.9 min). In general, subjects reported feeling more bloated and experienced greater stomach upset with the CW and CWC conditions.

Conclusion

All tested beverages are capable of promoting rehydration and supporting subsequent exercise. Little difference is noted between the four tested conditions with regard to markers of hydration or exercise performance in a sample of young, healthy men. Additional study inclusive of a more demanding dehydration protocol, as well as a time trial test as the measure of exercise performance, may more specifically determine the efficacy of these beverages on enhancing hydration and performance following dehydrating exercise.

Comparison of nutritional intake in US adolescent swimmers and non-athletes

Swimming is a very popular sport among adolescents in the US. Little is known about the diet of competitive adolescent swimmers in the US but data from other countries indicate several inadequacies, including excessive intake of fat and lower than recommended intake of carbohydrate and several micronutrients that may affect athletic performance and bone accrual. We assessed usual diet, using a food frequency questionnaire and calcium checklist, among 191 adolescent males and females [91 swimmers (mean 13.7, s = 2.5 years) and 100 non-athletes (mean 14.4, s = 2.8 years)]. For both males and females, swimmers and non-athletes generally had similar average intakes of macro- and micro-nutrients, including higher than recommended amounts of total fat (36%) and saturated fat (12%), and inadequate amounts of calcium, vitamin D, and daily servings of fruits, vegetables, grains, and dairy products. This first study of nutritional intake among adolescent swimmers in the US suggests that dietary habits of adolescents who swim competitively may jeopardize optimal athletic performance and place them at risk for future chronic diseases, including osteoporosis.

Carbohydrate mouth rinse effects on exercise capacity in pre- and postprandial States

Background. Oropharyngeal receptors signal presence of carbohydrate to the brain. Mouth rinses with a carbohydrate solution facilitate corticomotor output and improve time-trial performance in well-trained subjects in a fasted state. We tested for this effect in nonathletic subjects in fasted and nonfasted state. Methods. 13 healthy non-athletic males performed 5 tests on a cycle ergometer. After measuring maximum power output (Wmax), the subjects cycled four times at 60% Wmax until exhaustion while rinsing their mouth every 5 minutes with either a 6.4% maltodextrin solution or water, one time after an overnight fast and another after a carbohydrate rich breakfast. Results. Mouth rinsing with maltodextrin improved time-to-exhaustion in pre- and postprandial states. This was accompanied by reductions in the average and maximal rates of perceived exertion but no change in average or maximal heart rate was observed. Conclusions. Carbohydrate mouth rinsing improves endurance capacity in both fed and fasted states in non-athletic subjects.

Perceived protein needs and measured protein intake in collegiate male athletes: an observational study

BACKGROUND

Protein needs for athletes are likely higher than those for the general population. However, athletes may perceive their protein needs to be excessively high. The purpose of this research was to compare collegiate athletes' perceived protein needs and measured protein intake to the recommended protein intake (RDI) for healthy adults (i.e. 0.8 g/kg/d) and to the maximum beneficial level for strength-trained athletes (i.e. 2.0 g/kg/day).

METHODS

Perceived protein needs were quantified in 42 strength-trained collegiate male athletes by using a survey that asked the athletes to provide their perception about protein needs in specific quantitative terms (i.e. g/kg/d). Perceived protein needs were also determined by having the athletes select a daylong menu that they perceived to have adequate protein content from a collection of 5 isoenergetic menus, which differed in terms of protein content. Actual protein intake was quantified using 3-day food records and nutrient analysis. Single sample t-tests were used to compare protein intake and perceived protein needs to 0.8 g/kg/day and 2.0 g/kg/day.

RESULTS

When asked to provide, in quantitative terms, protein needs for athletes, 67% of the athletes indicated "do not know." Of the remaining 33% of athletes, all gave values greater than 2.0 g/kg/d (mean 21.5 ± 11.2 g/kg/d, p = 0.14 vs. 2.0 g/kg/d). Based on the menu selection method for determining perceived protein needs, the athletes indicated that their protein needs were 2.4 ± 0.2 g/kg/d, which was greater than the RDI for protein (p < 0.0001) and tended to be greater than the maximally beneficial protein intake of 2.0 g/kg/d (p = 0.13). Measured protein intake was 2.0 ± 0.1 g/kg/d, which was greater than the RDI (p < 0.0001) but not different from the maximally beneficial protein intake of 2.0 g/kg/d (p = 0.84).

CONCLUSIONS

Male collegiate athletes recognize that their protein needs are higher than that of the general population and consume significantly more protein than recommended in the RDI. However, it also appears that athletes are not aware of objective recommendations for protein intake and may perceive their needs to be excessively high. This study highlights the need for nutrition education in collegiate athletes, in particular nutrition education on macronutrient distribution and protein needs.

Eating for performance: bringing science to the training table

Despite many advances in nutritional knowledge and dietary practices, sports nutrition-associated issues, such as fatigue, loss of strength and stamina, loss of speed, and problems with weight management and inadequate energy intake, are common. Sound nutritional practices and well-designed patterns of eating are not awarded the same priority as training and many athletes fail to recognize that poor eating habits or suboptimal hydration choices may detract from athletic performance. Those who care for athletes and active individuals must take an active role in their nutritional well-being. This article reviews the present generally accepted principles for nutritional management in sport.

Sports drinks and energy drinks for children and adolescents: are they appropriate?

Sports and energy drinks are being marketed to children and adolescents for a wide variety of inappropriate uses. Sports drinks and energy drinks are significantly different products, and the terms should not be used interchangeably. The primary objectives of this clinical report are to define the ingredients of sports and energy drinks, categorize the similarities and differences between the products, and discuss misuses and abuses. Secondary objectives are to encourage screening during annual physical examinations for sports and energy drink use, to understand the reasons why youth consumption is widespread, and to improve education aimed at decreasing or eliminating the inappropriate use of these beverages by children and adolescents. Rigorous review and analysis of the literature reveal that caffeine and other stimulant substances contained in energy drinks have no place in the diet of children and adolescents. Furthermore, frequent or excessive intake of caloric sports drinks can substantially increase the risk for overweight or obesity in children and adolescents. Discussion regarding the appropriate use of sports drinks in the youth athlete who participates regularly in endurance or high-intensity sports and vigorous physical activity is beyond the scope of this report.

Effect of creatine, creatinine, and creatine ethyl ester on TLR expression in macrophages

Despite the widespread availability and use of dietary supplements, minimal work has been performed to assess the potential dangers many of these supplements may have on the host's well-being, in particular the host's ability to respond to infection. One supplement extensively used by both adolescents and adults is creatine. Using Real-time PCR, we examined the impact of short-term exposure of a mouse macrophage cell line (RAW 264.7 cells) to two readily available forms of creatine used in supplements--creatine monohydrate (CR) and creatine ethyl ester (CEE) as well as the end product of creatine metabolism, creatinine (CRN), on expression of toll-like receptor-2 (TLR-2), TLR-3, TLR-4, and TLR-7. CR down-regulated TLR-2, TLR-3, TLR-4 and TLR-7 mRNA levels in RAW cells. Similar results were observed following exposure of RAW cells to CRN. Conversely CEE appears to possess immunostimulatory properties and increases expression of TLR-2, TLR-3, TLR-4, and TLR-7 in RAW cells. These data are supported by immunostaining using antibodies specific for the individual TLRs before and after exposure of RAW cells to CR, CRN, or CEE. To extend these findings, we isolated murine splenocytes and exposed the cells to CR, CEE, or CRN for 24 hours and performed immunofluorescent staining for TLR-2, TLR-3, TLR-4 and TLR-7. The results obtained from this study with primary splenocytes were consistent with the studies using RAW cells. Together, these data suggest that creatine and creatine derivatives may impact the ability of immune cells to sense a wide array of viral and bacterial pathogens. Of great interest, CRN--largely considered to be a waste product of the argenine biosynthesis pathway may also have immunosuppressive properties similar to those of CR.

Associations among dietary supplement use and dietary and activity behaviors by sex and race/ethnicity in a representative multiethnic sample of 11th-grade students in Texas

BACKGROUND AND OBJECTIVE

The purpose of this study was to examine associations among dietary supplement use and dietary/activity patterns in a representative sample of adolescents by sex and race/ethnicity, a research area where extant data is limited.

DESIGN/PARTICIPANTS

Cross-sectional, multistage, probability-based sample of 11th graders in Texas during 2004-2005 (n=6,422; 48.8% white/other, 37% Hispanic, and 14.2% African American; 50.6% boys; mean age 16.7 years).

SETTING

Classrooms. MAIN VARIABLES ASSESSED: Dietary supplement use, dietary/activity patterns, and anthropometrics.

STATISTICAL ANALYSES PERFORMED

Multiple logistic regression models (odds ratios [ORs] and 95% confidence intervals [CIs]).

RESULTS

Dietary supplement users reported healthy dietary and physical activity behaviors overall, yet sex- and race/ethnicity-specific differences were seen in associations among specific diet/activity behaviors and supplement use. In whites/others and Hispanics, but not African Americans, supplement use was associated with higher diet quality scores (OR 2.93, 95% CI 1.74 to 4.95 for whites/others; OR 3.93, 95% CI 2.26 to 6.83 for Hispanics), and regular consumption of breakfast (OR 2.27, 95% CI 1.40 to 3.66 for whites/others; OR 1.96, 95% CI 1.11 to 3.46 for Hispanics) and low-fat foods (OR 3.02, 95% CI 1.53 to 5.98 for whites/others; OR 3.59, 95% CI 1.11 to 11.6 for Hispanics). Supplement use was not associated with body mass index or with sedentary behaviors overall, but was associated with less television viewing only in whites/others (OR 0.53, 95% CI 0.33 to 0.84). For physical activity, boys and whites/others showed positive associations between supplement use and all indicators examined, but girls, Hispanics and African Americans showed mixed patterns of associations. Supplement use was associated with higher weight preference only in boys (OR 2.47, 95% CI 1.24 to 4.90), and vegetarian diets only in girls (OR 2.96, 95% CI 1.35 to 6.47).

CONCLUSIONS

Dietary and activity patterns associated with dietary supplement use may vary by sex- and racial/ethnic subpopulation, especially amongst African American youth. These findings together with further research on psychosocial and attitudinal characteristics associated with adolescent supplement use can enhance the development of targeted and tailored health communications about supplement use in adolescent subpopulations.

The effect of vitamin A supplementation on various elements in elite taekwondo players

The present study aims to examine the effects of both physical activity and vitamin A supplementation on trace element metabolism in individuals engaged in taekwondo. The study registered seven healthy male national taekwondo players whose mean age was 21.86 ± 0.34 years and mean weight was 64.86 ± 2.72 kg. The subjects were supplemented with oral administration of 100 mg vitamin A (retinol) for 6 weeks, and concurrently, they were subjected to taekwondo training 5 days a week. Before starting the vitamin A supplementation, blood samples were taken from the subjects twice, once at rest and once after exhaustion. Similarly, at the end of the 6-week vitamin A supplementation, two blood samples were taken from the subjects, once at rest and once after exhaustion, in order to determine (by atomic emission) and compare serum cobalt, molybdenum, calcium, cadmium, chromium, copper, manganese, sodium, nickel, phosphorus, sulfur, iron, boron, and zinc (mg/L) levels. Values of boron and nickel dropped significantly after 6-week vitamin A supplementation (p < 0.001). Reduced levels of boron and nickel we obtained in the present study are believed to result from the antioxidant effect of long-term vitamin A supplementation.

Perfil nutricional de praticantes de corrida de rua de um clube esportivo da cidade de Belo Horizonte, MG, Brasil

O perfil antropométrico e/ou dietético de corredores de elite tem sido estudado; porém, pouco se conhece sobre estas características em praticantes de corrida de rua "recreacionais". O objetivo deste estudo foi caracterizar o perfil nutricional de praticantes de corrida de rua de um clube esportivo de Belo Horizonte (BH)/MG, encaminhados ao ambulatório de nutrição da clínica-escola de uma faculdade privada da cidade. A amostra foi composta por 19 indivíduos, na faixa etária entre 28 e 53 anos. Para o diagnóstico do estado nutricional foi obtida análise da adequação da ingestão de energia e dos macronutrientes - carboidratos (CHO), lipídios (LIP) e proteínas (PTN) - por meio do método recordatório de 24 horas (R24h), além da caracterização do perfil antropométrico. Os resultados da avaliação dietética indicaram que, segundo as recomendações propostas pelas DRIs (ingestão dietética de referência), a distribuição energética entre os macronutrientes em ambos os sexos encontra-se adequada sendo de 48,1 ± 9,2% (CHO); 29,6 ± 7,2% (LIP); e 22,3 ± 4,96% (PTN). Entretanto, quando se considera o consumo em g/kg de peso corporal, a ingestão de CHO apresentou-se baixa (3,54 ± 1,45g/kg/d) e a de PTN alta (1,7 ± 0,57g/kg/d) para esta modalidade esportiva. Quanto ao consumo energético total, 89,5% dos corredores estavam com ingestão energética abaixo dos valores recomendados, resultando em deficiência calórica diária. Em relação às características antropométricas, o percentual de gordura corporal (%GC) médio entre homens e mulheres não apresentou diferença estatística e mostrou-se adequado segundo a faixa etária. A circunferência da cintura (CC) e razão cintura quadril (RCQ) do grupo indicaram valores normais, não representando risco aumentado para doenças cardiovasculares. Concluímos que há indicativos que, apesar de os desportistas avaliados terem realizado distribuição energética em % adequada entre os macronutrientes, ainda não são suficientes para suprir as exigências energéticas da modalidade, necessitando, portanto, de constante orientação nutricional

Fuelling the athlete with type 1 diabetes

People with type 1 diabetes (T1DM) want to enjoy the benefits of sport and exercise, but management of diabetes in this context is complex. An understanding of the physiology of exercise in health, and particularly the control of fuel mobilization and metabolism, gives an idea of problems which may arise in managing diabetes for sport and exercise. Athletes with diabetes need to be advised on appropriate diet to maximize performance and reduce fatigue. Exercise in diabetes is complicated both by hypoglycaemia and hyperglycaemia in particular circumstances and explanations are advanced which can provide a theoretical underpinning for possible management strategies. Management strategies are proposed to improve glycaemic control and performance.