Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance

Development of novel calibration model(s) to predict whole-body density in professional football players

INTRODUCTION

Questions continue to be raised about the validity that is in existence to estimate Db, in professional male footballer players.

METHODS

Phase 1: n = 28 anthropometric variables were used on n = 206 footballers, using regression analyses to determine standard error of estimate and R2. A cut-off correlation coefficient set at r = 0.950 and 90% R2. Phase 2: all variables (z-scores, x -  = 0.0, SD = ±1.0) to help reduce heteroscedasticity, β, r, t, significance of t and P-values were calculated. Phase 3: a forced stepwise-backwards regression analysis approach with nine predictors which met the acceptance criteria (r = 0.950, R2 = 90% and β weights) was used to develop a 'best fit' and a 'practical' calibration model. Phase 4: cross-validation of the two newly developed calibration method using LoA.

RESULTS

The 'best fit' model SEM (0.115 g ml-1), the highest R2 (6.6%) (P  ≤ 0.005), whereas the 'practical' calibration model SEM (0.115 g ml-1), R2 (4.7%) (P  ≤ 0.005) with r values = 0.271 and 0.596 and R2 (%) coefficients = 0.3526 for the 'best fit' and 'practical' calibration models, respectively (P = 0.01).

CONCLUSIONS

The two calibration models supported an ecologically and statistically valid contribution and can provide sound judgements about professional footballers' body composition.

Sports Diet and Oral Health in Athletes: A Comprehensive Review

Food and fluid supply is fundamental for optimal athletic performance but can also be a risk factor for caries, dental erosion, and periodontal diseases, which in turn can impair athletic performance. Many studies have reported a high prevalence of oral diseases in elite athletes, notably dental caries 20-84%, dental erosion 42-59%, gingivitis 58-77%, and periodontal disease 15-41%, caused by frequent consumption of sugars/carbohydrates, polyunsaturated fats, or deficient protein intake. There are three possible major reasons for poor oral health in athletes which are addressed in this review: oxidative stress, sports diet, and oral hygiene. This update particularly summarizes potential sports nutritional effects on athletes' dental health. Overall, sports diet appropriately applied to deliver benefits for performance associated with oral hygiene requirements is necessary to ensure athletes' health. The overall aim is to help athletes, dentists, and nutritionists understand the tangled connections between sports diet, oral health, and oral healthcare to develop mitigation strategies to reduce the risk of dental diseases due to nutrition.

Effect of Various Hydration Strategies on Work Intensity and Selected Physiological Indices in Young Male Athletes during Prolonged Physical Exercise at High Ambient Temperatures

Background: In high temperatures, adequate hydration is vital for sustained physical exercise. This study explores the effect of three hydration strategies on physiological indices and work intensity. Methods: The research involved 12 healthy males who engaged in three test series, each separated by a one-week interval. During the trials, participants underwent a 120 min cycling session in a thermal climate chamber (temperature: 31 ± 2 °C, humidity: 60 ± 3%, air movement: <1 m/s). Measurements of rectal temperature (Tre) and heart rate (HR), and assessment of subjective workload perception, and thermal comfort were made both before and during the exercise. The computation of the physical strain index (PSI) relied on Tre and HR values. Three hydration strategies (isotonic drink, water, and no hydration) were administered before, during, and after the exercise. Results: Regardless of the hydration strategy, the participants' mean body mass decreased as a result of the exercise. Statistically significant differences in HR were observed between the no-hydration and water groups (p < 0.036). The mean PSI values significantly varied between hydration strategies, with the no hydration group exhibiting a higher PSI compared to the isotonic drink or water groups (p < 0.001). Conclusions: All hydration strategies contribute to thermoregulatory processes and mitigate the rise in internal body temperature during sustained physical exercise in elevated ambient temperatures.

Biochemical Aspects That Lead to Abusive Use of Trimetazidine in Performance Athletes: A Mini-Review

Trimetazidine (TMZ), used for treating stable angina pectoris, has garnered attention in the realm of sports due to its potential performance-enhancing properties, and the World Anti-Doping Agency (WADA) has classified TMZ on the S4 list of prohibited substances since 2014. The purpose of this narrative mini-review is to emphasize the biochemical aspects underlying the abusive use of TMZ among athletes as a metabolic modulator of cardiac energy metabolism. The myocardium's ability to adapt its energy substrate utilization between glucose and fatty acids is crucial for maintaining cardiac function under various conditions, such as rest, moderate exercise, and intense effort. TMZ acts as a partial inhibitor of fatty acid oxidation by inhibiting 3-ketoacyl-CoA thiolase (KAT), shifting energy production from long-chain fatty acids to glucose, reducing oxygen consumption, improving cardiac function, and enhancing exercise capacity. Furthermore, TMZ modulates pyruvate dehydrogenase (PDH) activity, promoting glucose oxidation while lowering lactate production, and ultimately stabilizing myocardial function. TMZs role in reducing oxidative stress is notable, as it activates antioxidant enzymes like glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD). In conclusion, TMZs biochemical mechanisms make it an attractive but controversial option for athletes seeking a competitive edge.

Popular Dietary Trends' Impact on Athletic Performance: A Critical Analysis Review

BACKGROUND

Nutrition fuels optimal performance for athletes. With increased research developments, numerous diets available, and publicity from professional athletes, a review of dietary patterns impact on athletic performance is warranted.

RESULTS

The Mediterranean diet is a low inflammatory diet linked to improved power and muscle endurance and body composition. Ketogenic diets are restrictive of carbohydrates and proteins. Though both show no decrements in weight loss, ketogenic diets, which is a more restrictive form of low-carbohydrate diets, can be more difficult to follow. High-protein and protein-paced versions of low-carbohydrate diets have also shown to benefit athletic performance. Plant-based diets have many variations. Vegans are at risk of micronutrient deficiencies and decreased leucine content, and therefore, decreased muscle protein synthesis. However, the literature has not shown decreases in performance compared to omnivores. Intermittent fasting has many different versions, which may not suit those with comorbidities or specific needs as well as lead to decreases in sprint speed and worsening time to exhaustion.

CONCLUSIONS

This paper critically evaluates the research on diets in relation to athletic performance and details some of the potential risks that should be monitored. No one diet is universally recommend for athletes; however, this article provides the information for athletes to analyze, in conjunction with medical professional counsel, their own diet and consider sustainable changes that can help achieve performance and body habitus goals.

Energy Expenditure, Dietary Energy Intake, and Nutritional Supplements in Adolescent Volleyball Athletes versus Nonathletic Controls

Evidence suggests that athletes competing in team sports do not follow dietary recommendations. However, only few studies have investigated energy needs and supplement use in adolescent athletes, and whether they are meeting their energy requirements. This observational study examined energy expenditure, dietary energy intake, and use of nutritional supplements in 58 adolescent (14-17 years old) volleyball athletes (15 males, 43 females) and 58 age-matched nonathletic controls (13 males, 45 females). Participants completed an online survey including questions on demographic information, body mass, and a series of standardized questionnaires assessing energy expenditure, dietary energy, macronutrient, micronutrient, and supplement intake. Energy expenditure relative to body mass was higher in athletes than nonathletes by 13 kcal/kg/day (group effect, p < 0.001), and in males compared to females by 5.7 kcal/kg/day (sex effect, p = 0.004). Athletes had higher energy intake than nonathletes (+6.4 kcal/kg/day, p = 0.019) and greater consumption of fruits (p = 0.034), vegetables (p = 0.047), grains (p = 0.016), dairy (p = 0.038), meats and meat alternatives (p < 0.001), as well as higher intakes of fat (p < 0.001), carbohydrates, protein, sugar, fiber, vitamin C, calcium, and sodium (p = 0.05) compared to nonathletes. The average protein intakes exceeded the upper recommendations in all groups, suggesting that this is not a nutrient of concern for young volleyball athletes. However, athletes were only meeting 60% of the estimated energy requirements (EER) for their age, height, body mass, and physical activity score, (3322 ± 520 kcal/day), while nonathletes were meeting 74% of the EER (p < 0.001). The relative energy balance of male athletes was lower compared to both female athletes (p = 0.006) and male nonathletes (p = 0.004). Finally, more athletes reported using performance-related supplements than nonathletes, but there were no differences in the consumption of other dietary supplements. Overall, when compared to nonathletic controls, both male and female adolescent volleyball athletes were found to match their higher energy expenditure with a greater dietary energy intake; however, all adolescents were below the estimated energy requirements, a finding more profound among the volleyball athletes.

Nutritional intake of sport undergraduates in Sabaragamuwa University of Sri Lanka

BACKGROUND

Nutritional intake plays an important role in determining energy availability which is vital to health, wellbeing, and sports performance in an active population. This research assessed the sports undergraduates' nutritional intake compared to the Dietary Guidelines for Americans and nutrition goals provided by WHO.

METHODS

This study is a quantitative, cross-sectional descriptive study. One hundred and one (n = 101) sports undergraduates aged between 20 to 23 years were recruited and the nutrient intake was assessed using the three-day food diary method and quantified the macro and micronutrients by the food composition database. One sample t-test was performed to compare the mean nutrient intakes with the lowest recommendation values.

RESULTS

Though most undergraduates were able to meet the dietary requirements in carbohydrates, they were deficient in their protein intake and exceeded in fats intake. Further, both male and female students were deficient in their daily energy intake (1723 kcal, 1607 kcal) and dietary fiber intake (8 g, 11 g). The saturated fat intake was met by all students while 20% of males and 21% of females exceeded the recommendations (< 10%). The micronutrient intake of vitamins such as C, B1, B2, B9, and B12 and minerals such as Calcium, Magnesium, and Potassium, were significantly below the recommendations (p < 0.05) except for vitamin B3 niacin.

CONCLUSIONS

Providing a nutritionally valuable meal is essentially required to maintain both physical and mental fitness. Our results revealed that the Sri Lankan sport science undergraduates do not have an adequate daily dietary intake of energy, proteins, calcium, magnesium, potassium, and vitamins such as C, B1, B2, B9, and B12.

The Role of Diets and Dietitians for Para-Athletes: A Pilot Study Based on Interviews

Efforts to provide nutrition support to para-athletes have not been established to date, and are far behind those established for athletes without disabilities. In the present study, we attempted to clarify the actual situation regarding dietary challenges of para-athletes. The aim of this study was to obtain clues to effective intervention methods that encourage the practice of sports nutrition. Six active elite para-athletes (30–70 years, four males) and a female physical therapist without physical disability participated in semi-structured interviews. All para-athletes had lower-limb disabilities and participated in the international wheelchair sports competitions (tennis, softball, and table tennis, with 2–26 years of player history). The interview items were on the ideal diet for improving competitive performance, evaluation of their typical diets, and the role of the dietitian as support. Responses obtained from participants were analyzed using quantitative content analysis by language analysis software. There are differences in the ideal diet based on the characteristics of the sport, but most participants believed that a nutritionally well-balanced diet with abundant vegetables was ideal for improving competitive performance. Para-athletes who use a wheelchair daily pay attention to their total calorie intake, because gaining weight is a critical issue for operating their wheelchairs and transferring themselves to and from their wheelchairs. Despite their world-class competition levels, none of them received routine dietary advice from dietitians. Some para-athletes did not even feel the need to engage with dietitians. Even for these para-athletes at a high level of competition, the “ideal diet” they considered was not always the optimal diet for improving their competitive performance. In addition, there are various barriers to practicing their optimal diet due to disability characteristics. Dietitians need to understand these barriers, their concerns and conflicts, and how to help them plan the optimal diet to improve their performance and maintain overall health.

Sex Differences in Anthropometric and Physiological Profiles of Hungarian Rowers of Different Ages

The aim of this study was to determine sexual differentiation in the anthropometric and physiological characteristics of Hungarian rowers in different age categories. These characteristics were measured for 15–16-year-old juniors (55 men and 36 women), 17–18-year-old older juniors (52 men and 26 women), and 19–22-year-old seniors (23 men and 8 women). The degree of sexual dimorphism was expressed in units of measurement as percentages and the dimorphism index. In all age categories, females had significantly higher body fat indices. Body fat percentage was determined by electrical impedance and by the Pařízková formula, BMI, and skinfold thicknesses. Males had significantly higher body mass, body height, skeletal muscle mass, sitting height, arm span, lower limb length, and body surface area. Males also scored significantly higher values for the following physiological characteristics: peak power, relative peak power, ErVO_2max, jump height, speed max, force max, and relative maximal power. Analysis of anthropometric and physiological characteristics in Hungarian rowers revealed that sexual dimorphism tended to increase with age, regardless of whether it was expressed in units of measurement, percentages, or dimorphism index values. The age-related increase in the sexual dimorphism of Hungarian rowers suggests that training methods should be carefully selected to accommodate the needs of various age and gender groups.

What Is the Evidence That Dietary Macronutrient Composition Influences Exercise Performance? A Narrative Review

The introduction of the needle muscle biopsy technique in the 1960s allowed muscle tissue to be sampled from exercising humans for the first time. The finding that muscle glycogen content reached low levels at exhaustion suggested that the metabolic cause of fatigue during prolonged exercise had been discovered. A special pre-exercise diet that maximized pre-exercise muscle glycogen storage also increased time to fatigue during prolonged exercise. The logical conclusion was that the athlete's pre-exercise muscle glycogen content is the single most important acutely modifiable determinant of endurance capacity. Muscle biochemists proposed that skeletal muscle has an obligatory dependence on high rates of muscle glycogen/carbohydrate oxidation, especially during high intensity or prolonged exercise. Without this obligatory carbohydrate oxidation from muscle glycogen, optimum muscle metabolism cannot be sustained; fatigue develops and exercise performance is impaired. As plausible as this explanation may appear, it has never been proven. Here, I propose an alternate explanation. All the original studies overlooked one crucial finding, specifically that not only were muscle glycogen concentrations low at exhaustion in all trials, but hypoglycemia was also always present. Here, I provide the historical and modern evidence showing that the blood glucose concentration-reflecting the liver glycogen rather than the muscle glycogen content-is the homeostatically-regulated (protected) variable that drives the metabolic response to prolonged exercise. If this is so, nutritional interventions that enhance exercise performance, especially during prolonged exercise, will be those that assist the body in its efforts to maintain the blood glucose concentration within the normal range.

Academy of Nutrition and Dietetics: Revised 2021 Standards of Practice and Standards of Professional Performance for Registered Dietitian Nutritionists (Competent, Proficient, and Expert) in Sports and Human Performance Nutrition

Nutrition in sports and human performance incorporates knowledge of the intersection of human physiology and nutrition. Registered dietitian nutritionist (RDN) practitioners in sports and human performance focus on nutrition care that is specific to the individual and their sport/occupational requirements. The Dietitians in Sports, Cardiovascular and Wellness Dietetic Practice Group, along with the Academy of Nutrition and Dietetics Quality Management Committee, have updated the Standards of Practice (SOP) and Standards of Professional Performance (SOPP) for RDNs working in sports and human performance. The SOP and SOPP for RDNs in Sports and Human Performance Nutrition provide indicators that describe three levels of practice: competent, proficient, and expert. The SOP uses the Nutrition Care Process and clinical workflow elements for delivering care to athletic/professional populations. The SOPP describes the following six domains that focus on professional performance: Quality in Practice, Competence and Accountability, Provision of Services, Application of Research, Communication and Application of Knowledge, and Utilization and Management of Resources. Specific indicators outlined in the SOP and SOPP depict how these standards apply to practice. The SOP and SOPP are complementary resources for RDNs and are intended to be used as a self-evaluation tool for assuring competent practice in sports and human performance and for determining potential education and training needs for advancement to a higher practice level in a variety of settings.

Mediterranean Diet Adherence, Body Composition and Performance in Beach Handball Players: A Cross Sectional Study

BACKGROUND

Beach handball (BH) is a sport in which sporting performance is influenced, together with team interaction, by individual performance in terms of strength. Body composition is one of the main factors for sports performance and eating habits can condition this variable. The Mediterranean diet (MD) can significantly reduce the risk of mortality or cardiovascular disease. In addition, the Spanish Ministry of Agriculture, Food and Environment carries out different campaigns to promote it among young athletes, establishing it as a suitable diet for sports.

OBJECTIVES

The main aims of the study are to assess body composition, physical activity and adherence to the MD of beach handball players. It also aims to evaluate age group differences in male and female players, as well as studying the possible relationship between MD, body composition and performance variables.

METHODS

A total of 59 Spanish BH players were recruited in the national championship of BH in the province of Alicante. Thirty-eight male (14 junior; 17.0 ± 0.1 years and 24 seniors; 25.5 ± 4.7 years) and twenty-one female (7 junior; 16.1 ± 1.46 years and 14 seniors; 23.2 ± 2.0 years) BH players participated in this study. The questionnaire to evaluate eating habits was Mediterranean diet adherence (KIDMED). Body composition was measured with electrical bioimpedance. Strength was evaluated by means of a maximum isometric handgrip test of the dominant hand with handgrip and height of jump by counter-jump on contact platform. In the statistical analysis, descriptions and correlations between the study variables were made.

RESULTS

In females, when the adherence to the MD is lower, the weight is higher, the lean body mass is lower and worse results are observed in performance tests. As for males, there are differences in weight and lean body mass according to category.

CONCLUSIONS

Adequate eating habits are related to the weight of beach handball athletes. In addition, specifically with junior players, it has been observed that adherence to the MD correlates with weight.

Efficacy of Vitamin D Supplementation in Physical Performance of Iranian Elite Athletes

Background:

There has been no report of the vitamin D status of the professional athletes from Iran to date. This study was performed to evaluate the efficacy of weekly vitamin D supplementation on athletic performance in Iranian athletes expedited to Asian competition in Taipei, China, 2015.

Methods:

This study was a randomized controlled clinical trial. Seventy subjects were enrolled in the study. The athletes were randomly divided into two groups: vitamin D supplement (D; received 50,000 IU of vitamin D supplement weekly) and control (P, received a placebo weekly). Duration of the study was 8 weeks. Anthropometric, dietary, athletic performance, and biochemical evaluations were performed for all subjects in the beginning and in the end of the intervention period.

Results:

A significant rise in circulating 25(OH)D concentration was observed in D group (17.3 ± 16.9 ng/mL, P < 0.001), whereas in P group, there was a statistically significant decrement (−3.1 ± 8.4 ng/mL, P = 0.040). There were no either within- or between-group significant differences in Ergo jump, vertical jump, and agility tests. In strength leg press tests, both groups showed a significant improvement. However, comparisons of changes revealed that the improvement in D group was significantly higher than in P group (P = 0.034). Moreover, in sprint test (one repetition-Max, 1RM), only D group had a significant within-group improvement (P = 0.030).

Conclusions:

Weekly supplementation with 50,000 IU vitamin D resulted in nearly 17 ng/mL increment in circulating calcidiol. This increase was associated with significant improvement of power leg press and sprint tests in D-supplemented group.

Predictive Factors of Elite Sprint Performance: Influences of Muscle Mechanical Properties and Functional Parameters

Loturco, I, Kobal, R, Kitamura, K, Fernandes, V, Moura, N, Siqueira, F, Cal Abad, CC, and Pereira, LA. Predictive factors of elite sprint performance: influences of muscle mechanical properties and functional parameters. J Strength Cond Res 33(4): 974-986, 2019-Sprint performance relies on many different mechanical and physiological factors. The purpose of this study was to identify, among a variety of strength-power exercises and tensiomyography (TMG) parameters, the best predictors of maximum running speed in elite sprinters and jumpers. To test these relationships, 19 power track and field athletes, 4 long jumpers, and 15 sprinters (men: 12; 22.3 ± 2.4 years; 75.5 ± 8.3 kg; 176.5 ± 5.6 cm; women: 7; 23.8 ± 4.2 years; 56.9 ± 5.4 kg; 167.4 ± 5.8 cm) were assessed using different intensities of TMG-derived velocity of contraction (Vc), squat and countermovement jumps, drop jump at 45 and 75 cm; and a 60-meter sprint time. In addition, the mean propulsive power (MPP) and peak power (PP) outputs were collected in the jump squat (JS) and half-squat (HS) exercises. Based on the calculations of the Vc at 40 mA, the athletes were divided (by median split analysis) into 2 groups: higher and lower Vc 40 mA groups. The magnitude-based inference method was used to compare the differences between groups. The correlations between mechanical and functional measures were determined using the Pearson's test. A multiple regression analysis was performed to predict sprint performance, using the Vc at 40 mA, jump heights, and JS and HS power outputs as independent variables. The higher Vc 40 mA group demonstrated likely better performances than the lower Vc 40 mA group in all tested variables. Large to nearly perfect significant correlations were found between sprint time, jump heights, and power outputs in both JS and HS exercises. Notably, the Vc 40 mA associated with the vertical jump height and MPP in JS explained >70% of the shared variance in sprint times. In conclusion, it was found that faster athletes performed better in strength-power tests, in both loaded and unloaded conditions, as confirmed by the strong correlations observed between speed and power measures. Lastly, the Vc also showed a marked selective influence on sprint and power capacities. These findings reinforce the notion that maximum running speed is a very complex physical capacity, which should be assessed and trained using several methods and training strategies.

Intermittent Dieting: Theoretical Considerations for the Athlete

Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The traditional approach requires continuous energy restriction (CER) for the entire weight loss phase (typically days to weeks). However, there is some suggestion that intermittent energy restriction (IER), which involves alternating periods of energy restriction with periods of greater energy intake (referred to as ‘refeeds’ or ‘diet breaks’) may result in superior weight loss outcomes than CER. This may be due to refeed periods causing transitory restoration of energy balance. Some studies indicate that intermittent periods of energy balance during energy restriction attenuate some of the adaptive responses that resist the continuation of weight and fat loss. While IER—like CER—is known to effectively reduce body fat in non-athletes, evidence for effectiveness of IER in athletic populations is lacking. This review provides theoretical considerations for successful body composition adjustment using IER, with discussion of how the limited existing evidence can be cautiously applied in athlete practice.

Evidence- and consensus-based recommendations for the use of pegvaliase in adults with phenylketonuria

Purpose

Phenylketonuria (PKU) is a rare metabolic disorder that requires life-long management to reduce phenylalanine (Phe) concentrations within the recommended range. The availability of pegvaliase (PALYNZIQ™, an enzyme that can metabolize Phe) as a new therapy necessitates the provision of guidance for its use.

Methods

A Steering Committee comprising 17 health-care professionals with experience in using pegvaliase through the clinical development program drafted guidance statements during a series of face-to-face meetings. A modified Delphi methodology was used to demonstrate consensus among a wider group of health-care professionals with experience in using pegvaliase.

Results

Guidance statements were developed for four categories: (1) treatment goals and considerations prior to initiating therapy, (2) dosing considerations, (3) considerations for dietary management, and (4) best approaches to optimize medical management. A total of 34 guidance statements were included in the modified Delphi voting and consensus was reached on all after two rounds of voting.

Conclusion

Here we describe evidence- and consensus-based recommendations for the use of pegvaliase in adults with PKU. The manuscript was evaluated against the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument and is intended for use by health-care professionals who will prescribe pegvaliase and those who will treat patients receiving pegvaliase.

Dietary intake of professional Australian football athletes surrounding body composition assessment

BACKGROUND

Sports Dietitians aim to assist in improving performance by developing nutrition knowledge (NK), enhancing dietary intake and optimising body composition of athletes. In a high-pressure environment, it is important to identify factors that may compromise an athlete's nutrition status. Body composition assessments are regularly undertaken in sport to provide feedback on training adaptions; however, no research has explored the impact of these assessments on the dietary intake of professional athletes.

METHODS

This cross-sectional study assessed dietary intake (7-day food diary), nutrition knowledge (Nutrition for Sport Knowledge Questionnaire) and body composition (Dual-energy X-ray absorptiometry) of 46 professional male Australian football (AFL) athletes during a 2017 pre-season training week (7 days) where body composition assessments were undertaken. Dietary intake was assessed against International Olympic Committee recommendations for professional athletes.

RESULTS

Overall, no athlete met dietary their recommended energy intake (15 ± 1.1 vs. 9.1 ± 1.8 MJ, respectively) or carbohydrate recommendations (6-10 vs. 2.4 ± 0.9 g·kg-1·day-1). Only 54% met protein recommendations. Secondary analyses demonstrated significant associations between education status and energy intake (P < 0.04) and vegetable intake (P < 0.03), with higher levels of education being associated with higher intakes. A moderately positive association was observed between NK scores and meeting estimated energy requirements (r = 0.33, P = 0.03). NK scores were also positively associated with protein (r = 0.35, P = 0.02), fibre (r = 0.51, P = 0.001) and calcium intakes (r = 0.43, P = 0.004).

CONCLUSIONS

This research identified that the dietary intake of professional AFL athletes during a pre-season training week where body composition assessments were undertaken did not meet current recommendations. Several factors may influence the dietary intake of AFL athletes, including lower education levels, poor NK and dietary intake restriction surrounding body composition assessment. Athletes may require support to continue with performance-based nutrition plans in periods surrounding body composition assessment.

Sports Nutrition for Young Athletes

Nutritional needs for peak athletic performance include sufficient calorie intake, adequate hydration, and attention to timing of meals. Student athletes and their advisors often are misinformed or have misconceptions about sports nutrition. This paper identifies nutritional needs of young athletes, reviews common misconceptions, and examines the nutrition knowledge of athletes and their sources of nutrition information. Topics covered include energy, carbohydrate, protein, fat and micronutrient needs, hydration requirements, timing of meals, and issues related to age, gender, and specific sports. Other issues addressed include “making weight” and ergogenic aids. Proper nutrition for young athletes is critical not only to their athletic success, but more importantly to their growth, development, and overall health. Nutritional recommendations should be based on the most current scientific data; we provide information about appropriate resources for the school nurse when advising student athletes and their coaches and parents.

Blood Glucose Levels of Subelite Athletes During 6 Days of Free Living

BACKGROUND

Continuous glucose monitoring (CGM) devices, with their 1-5 min measurement interval, allow blood glucose (BG) concentration dynamics to be captured more frequently and less invasively than traditional BG measures. One cohort CGM could provide insight is athletes. This study investigates what impact their heightened energy expenditure and dietary intake may have on their ability to achieve optimal BG.

METHODS

Ten subelite athletes (resting HR<60 bpm, training>6 hrs per week) were recruited. Two Ipro2 CGM devices (Medtronic Minimed, Northridge, CA) were inserted into the abdomen and remained in place for ~6 days. Time in band was calculated as the percentage of CGM BG measurements with in the 4.0-6.0 mmol/L. Fasting glucose was calculated using CGM calibration BG measurements and postprandial glucose response was also calculated using the CGM values.

RESULTS

4/10 athletes studied spent more than 70% of the total monitoring time above 6.0 mmol/L even with the 2-hour period after meals is excluded. Fasting BG was also in the ADA defined prediabetes range for 3/10 athletes. Only 1 participant spent substantial time below 4.0 mmol/L which was largely due to significantly lower energy intake compared to recommendations.

CONCLUSIONS

Contrary to expectations high BG appears to be more of a concern for athletes then low BG even in those with the highest energy expenditure and consuming below the recommended carbohydrate intake. This study warrants further investigation on the recommended diets and the BG of athletes to better determine the causes and impact of this hyperglycemia on overall athlete health.

Substrate Utilization and Cycling Performance Following Palatinose™ Ingestion: A Randomized, Double-Blind, Controlled Trial

(1) Objective: To compare the effects of isomaltulose (Palatinose™, PSE) vs. maltodextrin (MDX) ingestion on substrate utilization during endurance exercise and subsequent time trial performance; (2) Methods: 20 male athletes performed two experimental trials with ingestion of either 75 g PSE or MDX 45 min before the start of exercise. The exercise protocol consisted of 90 min cycling (60% VO₂max) followed by a time trial; (3) Results: Time trial finishing time (−2.7%, 90% CI: ±3.0%, 89% likely beneficial; p = 0.147) and power output during the final 5 min (+4.6%, 90% CI: ±4.0%, 93% likely beneficial; p = 0.053) were improved with PSE compared with MDX. The blood glucose profile differed between trials (p = 0.013) with PSE resulting in lower glycemia during rest (95%–99% likelihood) and higher blood glucose concentrations during exercise (63%–86% likelihood). In comparison to MDX, fat oxidation was higher (88%–99% likelihood; p = 0.005) and carbohydrate oxidation was lower following PSE intake (85%–96% likelihood; p = 0.002). (4) Conclusion: PSE maintained a more stable blood glucose profile and higher fat oxidation during exercise which resulted in improved cycling performance compared with MDX. These results could be explained by the slower availability and the low-glycemic properties of Palatinose™ allowing a greater reliance on fat oxidation and sparing of glycogen during the initial endurance exercise.

DO SIBERIAN YOGA PRACTITIONERS RISK HEALTH IF THEY FOLLOW LACTO VEGETARIAN DIET?

Background: Practicing yoga has become widely popular in Siberia and vegetarian diet constitutes one of its most important assumptions with a great impact on the human body. However, vegetarians are not the tradition in Siberia.Aim of the study: To evaluate the diet and assess whether Siberian yoga practitioners risk health reducing some nutrients’ intake. Material and methods: 47 Siberian women practicing yoga (program “Art of Living”), aged 31.9±7.4 years and the residents of Krasnoyarsk city were examined. Their height and weight were recorded. Then, the values of height and weight were used to calculate their BMI. After that, their current food consumption was assessed using a 24-hour nutritional recall. The recall was the basis to assess the quantitative content, composition and nutritional value of their average daily nutrition ration. The mean energy values and the levels of basic food components were calculated with the use of the computer program. The studies were conducted in the winter-spring period.Results: The data shows that, within the group of women examined in the study, over- or under-nutrition in accordance to the classification of BMI 20.88±2.51 kg/m2 have not been found. Their daily diet includes milk and dairy products, grains, legumes, nuts, cereals, vegetables, fruit, dried fruit, berries, leafy greens, seeds and herbs. Lacto vegetarian sportswomen have 4–5 meals a day with the use of up to 2 liters of water. The diet contains a variety of products and takes energy from carbohydrates, proteins and fats. The diet provides quantitative protein content, but it should be designed to avoid the use of proteins as the energy source. The ratio of proteins vs. fats vs. carbohydrates was 1 : 1 : 3.96, which can be considered as the norm for proteins and fats, but not for carbohydrates (recommendations for sportsmen 1 : 1 : 5). In our opinion, the energy goals were not met due to low intake of carbohydrates in women group practicing yoga in Siberia. The daily average consumption of vitamins in the group corresponds to the consumption of vitamins in the whole Russian population. Unfortunately, there is the imbalance between calcium (Ca), phosphorus (P) and magnesium (Mg) in the dietary habits which is not positive for the musculoskeletal system. We have also identified a high consumption of sodium (Na) and low of potassium (K), which can lead to some kidney and heart disorders. Conclusions: The research has helped us to answer the question whether Siberian yoga practitioners risk health if they are lacto vegetarians. Here are the findings: 1. Among lacto vegetarian yoga practitioners from Siberia over- or under-nutrition in accordance to the classification of BMI have not been found. 2. Lacto vegetarian yoga practitioners have appropriate nutritional habits: 4–5 meals a day with the use of up to 2 litres of water. 3. Food set has plastic, energy and biologically stimulating regulatory value. 4. Siberian female yoga practitioners have low (2%) probable risk of osteoporosis caused by inadequate intake of Ca in their daily diet and medium-risk (16%) of anemia caused by iron (Fe) deficiency and, therefore, they should supplement their diet using mineral supplements from the pharmacy. Certainly, vegetarians are not the tradition from the point of view of Siberia where it is difficult to find fresh vegetables, but lacto vegetarian diet can be successfully used.

Does Nutrition Knowledge and Practice of Athletes Translate to Enhanced Athletic Performance? Cross-Sectional Study Amongst Nigerian Undergraduate Athletes

INTRODUCTION & OBJECTIVES

Nutrition knowledge of an athlete, as well as practice, is expected to influence athlete's performance. The study assessed the nutrition knowledge and practice as well as athletes' performance and identified the factors predicting the athletes' performance.

METHODOLOGY

A cross-sectional survey, involved 110 purposively selected undergraduate athletes (47 females, 63 males) of University of Ibadan, Nigeria, between July 2013 and December 2013. A semi-structured, self-administered questionnaire assessed the nutrition knowledge and practice. 24-hr diet recall and food frequency questionnaire were done. Anthropometric measurements were taken; body composition was determined by bioelectrical impedance analysis method. Handgrip strength (HGS), as an indirect measure of athlete performance, was assessed with the hand dynamometer. Chi-square and t-test analysis were used for the bivariate analysis. Pearson correlation and simple linear regression were used to determine relationships and predict athletic performance. The level of statistical significance was p<0.05.

RESULTS

More than half (58.2%) had good nutrition knowledge (NK), and 62.7% had good nutrition practices (NP). Majority (75.4%) had normal handgrip strength (HGS). More than 70.0% frequently do not consume cereals, roots and tubers, fruits and vegetables, legumes /nuts. About 30.0-40.0% frequently do not consume eggs/milk, meat/fish. Having good NK was significantly associated with good NP (χ2=15.520, p=0.000), but not with athlete's performance (HGS). There is no significant correlation between NK, NP, and HGS. There is a significant positive correlation between HGS and lean muscle mass (LMM) (r=.670, p=0.000), weight (r=.492, p=0.000), height (r=.521, p=0.000) and energy intake (r=.386, p=0.000). There is a significant negative correlation between HGS and percentage body fat (r=-.400, p=0.000). Athletes' performance was significantly predicted by the resting metabolic rate (beta=.454 C.I=0.011 to 0.045, p=0.003), Lean muscle mass (beta=.297 C.I=.059 to 0.562, p=0.024) and the weight (beta=.228, C.I=1.852 to .489, p=0.047).

CONCLUSION

Having good nutrition knowledge or practice did not directly determine athletic performance. However, there is the need for nutrition education interventions, to improve athlete's performance by promoting adequate energy intake, lean muscle mass and appropriate weight gain in athletes.

Hair for brain trade-off, a metabolic bypass for encephalization

Hair loss in humans is perplexing and raises many hypothetical explanations. This paper suggests that hair loss in humans is metabolically related to encephalization; and that hair covered hominids would have been unable to evolve large brains because of a dietary restriction of several amino acids which are essential for hair and brain development. We use simulations to imply that hair loss must have preceded increase in brain size & volume. In this respect we see hair loss as a major force in human evolution. We assume that hair reduction required favorable climatic conditions and must have been quick. Using evolutionary and ecological time scales, we pinpoint hair loss to a period around 2.2-2.4 million years ago. The dating is further supported by a rapid selection at that time of the sialic acid deletion mutation which may have protected growing human brains against calcium ion flux. In summary we view encephalization, in part, as a metabolic trade-off between hair and brain. Other biochemical changes may have intervened in the process too; and the deletion mutation of sialic acid hydroxylation may have been involved as well.

Monitoring and prevention of anemia relying on nutrition and environmental conditions in sports

Conflict of interest: none declared.

The making of a nutrition professional: the Association for Nutrition register

OBJECTIVE

Nutritionists in the UK are at the start of an exciting time of professional development. The establishment of the Association for Nutrition in 2010 has presented an opportunity to review, revitalize and expand the UK Voluntary Register of Nutritionists. In the UK and elsewhere, there is a need for a specialist register of nutritionists with title protection as a public safeguard.

DESIGN

The new structure will base professional registration on demonstration of knowledge and application in five core competencies. Initially, there will be five specialist areas: animal; public health; nutritional scientist; food; sports and exercise. The wording and requirements linking the specialist areas to the competencies have been carefully defined by leading individuals currently on the existing register in these specialist areas. These have been evaluated by a random sample of existing registrants to check for accuracy of definitions and examples. Other work aims to establish a clear quality assurance framework in nutrition for workers in the health and social care sectors (UK Public Health Skills and Career Framework Levels 1-4) who contribute to nutrition activity, such as community food workers, nutrition assistants and pharmacists. Students, co-professional affiliates and senior fellows will also find a place in the new Association. The title 'nutritionist' is not currently legally protected in the UK and it is used freely to cover a range of unregulated practice.

CONCLUSIONS

The establishment of a professional register to protect the public and to provide a clear identity for nutritionists is a vital step forward.

Consumption and biochemical impact of commercially available plant-derived nutritional supplements. An observational pilot-study on recreational athletes

BACKGROUND

A growing consumption of natural (plant-derived) dietary supplements with ergogenic aims, with particular regard for ecdysteroids, phytoestrogens and vegetal sterols, has been registered over the last years among "recreational" athletes. The present study was carried out in order to evaluate the real knowledge of plant-derived nutritional supplements among physically active people as well as their real consumption. Additional aim was to evaluate the effects of these supplements on the health profile of the users.

METHODS

Twenty-three trained subjects who habitually used natural dietary supplements, and 30 matched controls were analyzed for plasma biochemical markers and hormonal profile.

RESULTS

The laboratory tests revealed the absence of any sign of organ toxicity/damage in both athletes and controls. On the contrary, hormone profiles revealed marked alterations in 15 (65%) out of the 23 of investigated athletes. Specifically, 10 males presented increased plasma levels of progesterone, 15 subjects presented abnormal estrogen levels, including 5 (2 F and 3 M) presenting a "dramatic" increased estrogen values and 2 two males with increased estrogen levels, increased testosterone levels and associated suppression of luteinizing hormone and follicle-stimulating hormone.

CONCLUSIONS

The results of the present study highlighted that the habitual consumption of plant-derived nutritional supplements is frequently associated with significant hormonal alterations both in male and female subjects. Although these biochemical alterations were not associated with signs or symptoms of organ toxicity/damage at the moment of the study, it cannot be excluded that, in the mid/long-term, these subjects would suffer of health problems secondary to chronic exposure to heavily altered hormonal levels. Further large scale studies are needed to confirm the results of this pilot study as well as to investigate the biological mechanisms at the base of the observed hormonal alterations.

Contaminação de suplementos dietéticos usados para prática esportiva: uma revisão de literatura

O objetivo do presente estudo foi revisar a literatura que trata da contaminação dos suplementos alimentares por substâncias consideradas nocivas à saúde ou doping para os atletas. Para tanto, foram revisados artigos científicos indexados nas bases de dados Medline e Scielo. Foi possível observar que algumas investigações detectaram doses excessivas de ingredientes potencialmente tóxicos, não indicados no rótulo e considerados doping. Entre as substâncias proibidas encontradas em alguns suplementos estão os esteróides anabólico-androgênicos e os psicoestimulantes. Neste sentido, é possível alegar que o uso de suplementos dietéticos por praticantes de atividades físico-esportivas, competitivas ou não, carece de maior segurança e deve ser realizado com muito critério.

Evaluation of the nutrition knowledge of sports department students of universities

BACKGROUND

Individuals who have knowledge on the importance of adequate and balanced diet and reflect this knowledge to their behaviors are considered to be more successful in sports life. The present study aims to evaluate the nutrition knowledge of students receiving sports education in universities.

METHODS

The study sample consists of 343 voluntary students from the Sports Departments of Hacettepe, Gazi and Ankara Universities in Ankara. The questionnaire used in the study included a demographic section, and 30 questions on true-false nutrition knowledge. For the reliability of the questionnaire, the internal consistency coefficient was calculated and the Kuder Richardson (KR-20) value was found to be 0.71. For higher reliability, 9 dysfunctional questions were excluded from the questionnaire. The research data were collected through a questionnaire form and face-to-face interviews. For the statistical analyses of the data, tables were prepared to show mean, standard deviation (X̄±SD) and percentage (%) values. In order to determine the nutrition knowledge of students, the "independent t test" was used for nutrition lesson and gender.

RESULTS

University students receiving sports education and expected to continue their professional lives on sport-related fields were determined to have the lack of knowledge on nutrition. The mean value about the nutrition knowledge of the first year students was found 11.150 ± 2.962, while the mean value of the fourth year students was 13.460 ± 3.703, and the difference is statistically significant (p = .000).

CONCLUSION

Students, coaches and teachers in physical education were found not to give the necessary importance to their diets, and they were still not aware of the importance of nutrition on performance.

Gateway to doping? Supplement use in the context of preferred competitive situations, doping attitude, beliefs, and norms

Nutritional supplement (NS) use is widespread in sport. This study applied an integrated social cognitive approach to examine doping attitudes, beliefs, and self-reported doping use behavior across NS users (n = 96) and nonusers (n = 116). Following ethical approval, 212 competitive athletes (age mean = 21.4, s = 4.5; 137 males) completed self-reported measures of doping-related social cognitions and behaviors, presented in an online format where completion implied consent. Significantly more NS users (22.9%) reported doping compared with nonusers (6.0%; U = 4628.0, P < 0.05). NS users presented significantly more positive attitudes toward doping (U = 3152.0, P < 0.05) and expressed a significantly greater belief that doping is effective (U = 3152.0, P < 0.05). When presented with the scenario that performance-enhancing substances are effective and increase the possibility of winning, NS users were significantly more in favor of competing in situations that allow doping (U = 3504.5, P < 0.05). In sum, doping use is three-and-a-half times more prevalent in NS users compared with nonusers. This finding is accompanied by significant differences in doping attitudes, norms, and beliefs. Thus, this article offers support for the gateway hypothesis; athletes who engage in legal performance enhancement practices appear to embody an "at-risk" group for transition toward doping. Education should be appropriately targeted.

Physiological profile of elite Iranian junior freestyle wrestlers

The purpose of the present investigation was to describe the physiological profile of elite Iranian junior freestyle wrestlers. Seventy elite wrestlers (age 19.8 +/- 0.9 years) who were invited to the national training camps, based on their top 10 national ranking, participated in this study. The physiological profile included body weight, flexibility (sit and reach test), maximal oxygen consumption (Bruce protocol), maximal anaerobic power of the legs (Wingate test), muscular endurance and strength (bench press, squat, pull-ups, push-ups, grip strength, and bent-knee sit-up test), speed (40-m sprint), agility (4 x 9-m shuttle run), and body composition (7-site skinfold). The major results (mean +/- SD) are as follows: body weight (kg): 77.5 +/- 19.8; flexibility (cm): 38.2 +/- 3.94; maximal oxygen consumption (ml kg(-1) min(-1)): 50.5 +/- 4.7; maximal anaerobic power of the legs (W): 455.5 +/- 87.6; 1-repetition maximum bench press (weight lifted kg body weight(-1)): 1.4 +/- 0.15; 1-repetition maximum squat (weight lifted kg body weight): 1.7 +/- 0.2; push-ups (n): 66.9 +/- 7.6; pull-ups (n): 31.6 +/- 9.7; grip strength (force in kg body weight kg(-1)) 1.02 +/- 0.11; bent-knee sit-ups (n): 66.5 +/- 8; speed (s): 5.07 +/- 0.17; agility (s): 8.7 +/- 0.25; and body fat (%): 10.6 +/- 3.8. The present study provides baseline physiological data that have been used in the prescription of individual training programs for these athletes. This information is also available to the coaches and can contribute to the general strategy employed by a wrestler and for a specific match.

The female athlete triad: components, nutrition issues, and health consequences

This paper, which was part of the International Association of Athletics Federations (IAAF) 2007 Nutritional Consensus Conference, briefly reviews the components of the female athlete triad (Triad): energy availability, menstrual status, and bone health. Each component of the Triad spans a continuum from health to disease, and female athletes can have symptoms related to each component of the Triad to different degrees. Low energy availability is the primary factor that impairs menstrual dysfunction and bone health in the Triad. We discuss nutritional issues associated with the Triad, focusing on intakes of macronutrients needed for good health, and stress fractures, the most common injury associated with the Triad. Finally, we briefly discuss screening and treatment for the Triad and the occurrence of the Triad in men.

Nutrition concepts for elite distance runners based on macronutrient and energy expenditure

CONTEXT

Elite distance runners (EDR) must optimize their nutrition to maintain their demanding training schedules.

OBJECTIVE

To develop a nutrition concept for EDR based on energy and macronutrient expenditures.

DESIGN

This theoretical study provides calculations for macronutrient and energy expenditures of EDR. Anthropometric and metabolic characteristics of EDR were assumed based on average real EDR.

SETTING

University of Kiel.

PATIENTS OR OTHER PARTICIPANTS

Three prototypic types of male EDR described in the literature as type I (TI; body mass = 72 kg, respiratory quotient = 0.9 at rest, fast-twitch muscle fibers = 60% to 70%), type II (TII; body mass = 67 kg, respiratory quotient = 0.82 at rest, fast-twitch muscle fibers = 50%), and type III (TIII; body mass = 60 kg, respiratory quotient = 0.75 at rest, fast-twitch muscle fibers = 30% to 40%).

MAIN OUTCOME MEASURE(S)

We calculated the macronutrient and energy expenditures of the 3 types of EDR according to body mass, respiratory quotient, and percentage of fast-twitch muscle fibers.

RESULTS

We found that the average energy expenditure was 3750 kcal . d(-1) for TI runners, 3463 kcal . d(-1) for TII runners, and 3079 kcal . d(-1) for TIII runners. The carbohydrate (CHO) expenditure reached an average value of 10.0 g . kg(-1) . d(-1) for TI runners, 8.0 g . kg(-1) . d(-1) for TII runners, and 4.7 g . kg(-1) . d(-1) for TIII runners. When the EDR accomplished running sessions at a pace >or=100% of maximum oxygen consumption, all types of runners had a CHO demand of about 10 g . kg(-1) . d(-1). The TI and TII runners need a CHO intake of 8 to 10 g . kg(-1) . d(-1). For the TIII runners, a CHO intake >6 g . kg(-1) . d(-1) is necessary during anaerobic training sessions.

CONCLUSIONS

Nutrition concepts must be differentiated for EDR according to metabolic and anthropometric characteristics of the runners and their special training emphases.

Body composition and nutritional profile of male adolescent tennis players

In this cross-sectional study, we evaluated the body composition and dietary intake of 44 adolescent tennis players. After being divided into two groups (age 10-13 years and age 14-18), the players had their weight, height, and sexual maturation assessed. Dual-energy X-ray absorptiometry was used to assess body composition. Food intake was obtained from a non-consecutive 4-day food record. The data were analysed using the Virtual Nutri v.1.0 software and compared with the present recommendations for adolescent athletes or dietary reference intakes. Body mass index and body fat for tennis practice were adequate for 89% and 71% of the tennis players respectively, regardless of age group. A calorie deficit greater than 10% of energy expenditure was observed in 32% of the sample. Fifty percent of the athletes consumed carbohydrates in accordance with recommended values. Protein and lipid intakes were above recommended values, while fibre, calcium, potassium, magnesium, and folic acid intakes were below recommendation for 98%, 80%, 100%, 100%, and 98% of the tennis players respectively. The observed nutritional deficiencies represent an additional barrier for adolescents engaged in competitive sports to achieve an optimum nutrition to maintain growth, health, and performance.

Consumo de suplementos por jovens freqüentadores de academias de ginástica em São Paulo

A preocupação com a aparência e a estética pode levar ao consumo indiscriminado de suplementos nas academias. Os fatores relacionados ao consumo de suplementos em 201 jovens entre 15 e 25 anos freqüentadores de academias de ginástica da cidade de São Paulo foram investigados através da aplicação de formulário próprio. O uso de suplementos é relatado por 61,2% (n = 123) da amostra. Os homens usam mais suplementos que as mulheres (p < 0,001) e os adolescentes tendem a utilizar mais que os adultos jovens (p = 0,07). Os suplementos mais utilizados são bebidas esportiva (12%), hipercalóricos (12%), aminoácidos (10%), proteínas (10%) e creatina (8%), basicamente por auto-prescrição (42,8%) e pela indicação de treinadores (27,5%). O consumo de suplementos é significativamente maior entre aqueles que se exercitam há mais tempo; freqüentam a academia há mais tempo; e ficam na academia mais horas/semana. Ter amigos usuários (p = 0,03) e/ou um usuário em casa (p = 0,01) influencia no consumo de suplementos. O consumo de suplementos é uma prática que faz parte da realidade das academias de ginástica e o ambiente é favorecedor do uso desses produtos.