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Nutritional Requirements of the Child and Teenage Athlete
Abstract
There has been an explosion in sports participation, especially for women, in the last 35 years mainly because of Title IX. In 2005-2006, nearly 3 million girls and 4.2 million boys participated in high school athletics, and many more participated in club sports and recreational activities. On the other end of the spectrum, the prevalence of obesity in the United States is at an all-time high. Proper nutrition in combination with the appropriate amount of physical activity is of paramount importance for this era of adolescents.
... The intake of sufficient energy, timing of meals, and proper hydration are areas of focus that the young athlete needs to consider when formulating a training regime [13][14][15][16][17]. Adolescent athletes are a unique population, since they not only need fuel for daily athletic events but also need to consume a well-balanced diet to ensure optimal growth and health [13,15]. ...
... The intake of sufficient energy, timing of meals, and proper hydration are areas of focus that the young athlete needs to consider when formulating a training regime [13][14][15][16][17]. Adolescent athletes are a unique population, since they not only need fuel for daily athletic events but also need to consume a well-balanced diet to ensure optimal growth and health [13,15]. Sports nutrition is becoming more prominent in all facets of the sporting world [18] and ice hockey players are becoming more interested in learning about nutrition and how it relates to their performance outcomes. ...
... Vitamin A (mcg RAE) 600 833 ± 77 (9/10) 674 ± 62 * (5/10) Vitamin D (µg) 15 6 ± 1 (0/10) 5 ± 2 (1/10) Vitamin E (mg) 11 ...
This study recorded the dietary intakes of young male ice hockey players (10–13 year (yr)) for 3 consecutive days while participating in a 5-day summer hockey camp. Players were categorized as older children (OC, n = 10; 10.7 ± 0.2 yr; 37.1 ± 1.5 kg; 147.9 ± 2.1 cm) and young adolescents (YA, n = 10; 12.9 ± 0.1 yr; 45.2 ± 1.5 kg; 157.0 ± 2.4 cm). Players consumed their usual daily intakes. Parents recorded food intake in the mornings and evenings, while the researchers recorded food intake at camp. Energy intake was higher in both groups when compared to data for age-matched young Canadian (CDN) males (OC, 2967 ± 211 vs. 2000 kcal/day; YA, 2773 ± 91 vs. 2250 kcal/day). Carbohydrate (CHO) (OC, 11.2 ± 0.8 vs. YO, 8.9 ± 0.5 g/kg body mass/day) and protein (OC, 3.2 ± 0.3; YO, 2.4 ± 0.1 g/kg/day) intakes were higher than reported for young CDN males (CHO, 3.6 and protein, 1.0 g/kg/day) and were within the Acceptable Macronutrient Distribution Range (AMDR; CHO, 56 ± 2.3; 57.4 ± 0.8%; protein, 16.1 ± 1.0; 15.7 ± 0.7%). Fat intake was also within the AMDR in both groups (OC, 29.8 ± 1.6%; YA, 28.3 ± 1.0%). Micronutrient intake was adequate except for Vitamin D intakes that were below the recommended 15 ug/day at 6.3 ± 0.7 (OC) and 5.0 ± 1.5 ug/day (YA). In summary, energy and macronutrient intakes of the OC (10–11 yr) and YA (12–13 yr) players were high and well above the age matched CDN norms. The older children had higher energy intakes/kg body mass than the young adolescents. Higher energy intakes allowed for micronutrients intakes to be met in these young active males, except for vitamin D intake.
... Polysaccharides in the date flesh and seeds or pits contain xylose, arabinose, glucose, and galactose (Shafiei et al., 2010). Semi-dry dates have nearly 50% each of sucrose and reducing sugars (Hassan et al., 2017) and contain more sucrose than reducing sugars (Djaoud et al., 2019). Dry dates with solid and dry flesh contain relatively more sucrose than reducing sugars. ...
... In addition, fresh dates contain higher concentrations of vitamins than dried dates as a result of the depletion of vitamins during the drying process. Thiamin, riboflavin, niacin, ascorbic acid, pyridoxine, and vitamin A are present in dried dates in relatively low concentrations (Hamad et al., 2015;Hassan et al., 2017). ...
... One food source that contains appropriate amounts of both macro-and micronutrients is essential for the energy and nutrition needs of athletes. Dates could fulfill these nutrition requirements for athletes and enhance their performance by reducing fatigue and the risk of injury and recovery (Ghazal et al., 2016;Hoch et al., 2008). ...
The purpose of this review was to provide information about the chemical composition and nutritional benefits of date fruits, known more commonly as dates. We also present the potential application of dates in energy nutrition bars for athletes. Dates have a high nutritional value and are rich in carbohydrates, dietary fibers, proteins, minerals, and many vitamins including B complex. Carbohydrates comprise 70% of dates mainly as fructose and glucose. In addition, dates are rich in calcium, iron, magnesium, selenium, copper, phosphorus, potassium, zinc, sulfur, cobalt, fluorine, and manganese. Recently, there has been enhanced interest in the abundant health-promoting properties of dates, and this has led to the need to develop food products that use dates as a rich source of nutrients. Dates thus have a great potential for application as a food ingredient in dietary supplements, energy nutrition bars and as a functional food for athletes
... According to Hoch et al. [1], the term diet refers to the collection of such type of food which helps to improve the physical condition, controls weight and helps to cure diseases by making the immune system strong. Similarly, Khan [2] defines the sports diet as the diet, which need by athlete before, during and after the activity. ...
... Sports diet has been one of the basic needs of every sportsmen participating at various level of sports. According to Hoch et al. [1], sports diet enhances athletic performance by decreasing fatigue and the risk of disease and injury; it also enables athletes to optimize training and recover faster. Athletes must fuel their bodies with the appropriate nutritional foods to meet their individual energy requirements in competition, training and recovery. ...
... Diet refers to the collection of such type of food, which helps to improve the physical condition, controls weight and helps to cure diseases by making the immune system strong [1]. Use of diet directly linked with physical structure and intensity of the activities which is to be performed because some activities are high powered in nature such as football, tennis, and hockey, requiring large amounts of work, rapid movements, and more energy while others are more endurance-based, such as cross-country running and triathlon training, which require continual lower force outputs for longer durations. ...
The focus of this research study was to assess the perception of athletes about diet and its role in the maintenance of performance. The target population of this research study was comprised of all the players of different sports clubs of District Bannu. Two hundred and six (206) players were randomly selected as sample of the study. For the collection of data, the researcher developed a closed form of questionnaire. The developed questionnaire personally served by the researcher among the respondents and collected back after getting it filled by the respondents. The collected data were tabulated and analyzed by using percentage and mean average as statistical tool. After data analysis, the researcher arrived at conclusion that proper diet is the basic requirement of athletic performance. The data also revealed that carbohydrates, protein, fats, vitamins, minerals and water are more important to consume in proper amount for sports participation.
... Les aliments de base sont importants pour la croissance, la santé et les résultats scolaires, ainsi que pour fournir de l'énergie (1). La nutrition sportive améliore la performance athlétique, car elle réduit la fatigue et le risque de maladies et de blessures. ...
... La nutrition sportive améliore la performance athlétique, car elle réduit la fatigue et le risque de maladies et de blessures. Elle permet également aux athlètes d'optimiser leur entraînement et de récupérer plus rapidement (1). Il est capital d'équilibrer l'apport énergétique avec la dépense d'énergie pour prévenir un déficit ou un surplus énergétique. ...
... Ces apports énergétiques recommandés correspondent au minimum nécessaire pour favoriser une croissance optimale et de bonnes fonctions organiques. Il faut des calories supplémentaires pendant les poussées de croissance et pour récupérer l'énergie perdue pendant les activités athlétiques (1,5,6). Par exemple, une fille de 30 kg qui jouerait au soccer pendant 60 minutes dépenserait en moyenne 270 calories, tandis qu'un garçon de 60 kg qui jouerait au hockey sur glace pendant 60 minutes dépenserait en moyenne 936 calories (6). ...
... However, the nutritional needs of teenagers who do sports, often involving one or more daily training sessions, are vastly different. In such cases, not only does proper nutrition influence the maintenance of the optimal rate of physical development of children, but it also improves their sports performance and protects them from the occurrence of injuries related to muscle exhaustion [1][2][3]. Nutrition for a young athlete is not only a challenging task for parents, but also for sports supervisors and athletes themselves. They need to learn the principles of healthy nutrition and then implement them into their daily lives, thereby accelerating recovery after exercise, but also, importantly, reducing the health effects of an improper diet. ...
... Meanwhile, in the literature there is a dearth of studies on nutritional interventions among young soccer players. The adoption of appropriate nutrition education should allow athletes to prepare optimally for competition, and enable them to stay healthy and reach their athletic potential in their further sports careers [1,7,8]. ...
In adolescence, the body requires sufficient amounts of adequate nutrients. This is especially important in the case of young athletes, for whom a nutrition plan should be as significant as a proper training plan. The aim of the study was a 17-week follow-up of the effects of individual and group nutrition intervention on changes in eating habits and selected biochemical parameters. 46 young soccer players aged 12–17 from the Soccer Academy in Northeastern Poland completed the study. One group received only individual recommendations, while the other additionally received group nutrition education. As a result of the dietary education, teenagers from the latter group consumed less saccharose (44 g vs. 39.2 g) in favor of digestible carbohydrates (266 g vs. 273 g) and dietary fiber (19.7 g vs. 22.2 g), further emphasizing the health-promoting profile of diets. The amount of fluid consumed (33% vs. 48% above 2 L of water a day) and the habits of the peri-workout hydration routine were also improved. Many of the participants (41%) reported faster regeneration while 26% experienced an overall better well-being. The short-term intervention produced positive results, but nevertheless it is the implementation of long-term dietary improvement schemes involving parents and coaches that should be the direction of future approaches.
... W takich wypadkach gdy ilość treningu i obciążenia treningowe są zmienne lub wzrastają, koniecznym rozwiązaniem powinno być zwiększenie ilości kalorii w diecie, przez wprowadzenie zdrowych, dodatkowych przekąsek około treningowych o dużej koncentracji energii w małej objętości np. owoców świeżych (banany) i suszonych, orzechów czy musli z mlekiem (Hoch, 2008). ...
... Efektem tego zjawiska może być zmęczenie, problemy ze snem, pamięcią i koncentracją, pogorszenie kondycji zdrowotnej, spadek odporności, zaburzenia wzrostu, zaburzenia gospodarki hormonalnej czy zaburzenia homeostazy tkanki kostnej. W kontekście treningowym osłabieniu ulegają cechy psychomotoryczne takie jak szybkość czy koncentracja, zmniejszają się zdolności wysiłkowe i zwiększa podatność na kontu-zje (Hoch, 2008). Równoważenie poboru energii z wydatkami energetycznymi organizmu ma kluczowe znaczenie dla uniknięcia deficytu lub nadwyżki energii. ...
Opracowanie jest efektem badań prowadzonych w Akademii Wychowania Fizycznego im. Jerzego Kukuczki w Katowicach dotyczących wybranych zagadnień z zakresu szeroko rozumianych zachowań zdrowotnych, ze szczególnym uwzględnieniem aktywności fizycznej. Treści zawarte w pracy są związane z oceną: możliwości zastosowania w monitoringu aktywności fizycznej technologii mobilnych i teleinformatycznych, intensywności i atrakcyjności wysiłku fizycznego w wirtualnej rzeczywistości, zachowań zdrowotnych osób z różnych grup społecznych i zawodowych, związków aktywność fizycznej ze stylami radzenia sobie ze stresem oraz wpływu wysiłków fizycznych na poprawę regulacji temperatury ciała kobiet i mężczyzn. Książka jest kierowana przede wszystkim do studentów kierunków związanych z kulturą fizyczną, fizjoterapeutów, nauczycieli wychowania fizycznego, trenerów personalnych, instruktorów fitness i przedstawicieli innych pokrewnych zawodów.
... During childhood and adolescence, it is mandatory to maintain adequate blood iron levels to ensure growth and the rise in blood volume and lean muscle mass. 35 Children aged between 9 and 13 years must ingest 8 mg/day to avoid depletion in their iron reserves and iron deficiency anemia. Adolescents aged between 14 and 18 years require a higher amount of iron, up to 11 mg/day for males and 15 mg/day for females. ...
... 1). 35,44 The intake of liquids containing sodium after exercise helps rehydration by stimulating thirst and liquid retention. Nonathletic individuals should avoid a regular intake of sports drinks containing CH since they can lead to an excessive calorie intake, increasing the risk of overweight, and tooth decay. ...
Child athletes require a healthy and balanced nutrition according to the type and intensity of the sport activity. This review aims to provide integrated and updated information to establish adequate nutritional guidelines for these children, essentially avoiding deficiencies or unbalances that can be harmful for their health. A lack of vitamins and minerals can affect their health especially at long term and depending on the type of sport and age of the child. The diet must be controlled without any nutritional supplements. It is also important to know which nutrients can improve performance of the child athlete during both training and competition. In conclusion, the contribution of macro- and micronutrients to the diet, together with an adequate hydration according to the energy expenditure must be controlled for child athletes to ensure a good status of health.
... Such eating behaviour increases the risk of obesity, diabetes, hypertension and other cardiovascular diseases, and cancer in adult life [15][16][17][18]. In particular, the diet of sport active adolescents should include not only the puberty needs, but also related to the increased PA [19][20][21][22][23]. ...
(1) Background: Diet and physical activity (PA) significantly impact health. The aim of this study was to evaluate the impact of long-term increase in organized PA level at school on the eating behaviour and leisure time of early adolescences in the period from the age of 10 to 12. (2) Methods: Children born in 2007 (n = 278) in groups with a standard (control group) and increased level of organized PA at school (4 and 10 h a week) were subjected to an anonymous follow-up survey. The questionnaire included 22 questions related to the eating behaviour and ways and frequency of leisure time PA. The study was conducted in the same groups in three assessment sessions in September 2017, 2018 and 2019. (3) Results: During the course of the study, it was shown improvement of eating behaviour in the increased PA group whereas decline in the standard PA one. The share of children with good and very good scores of eating behaviour decreased in the standard PA group from 56.89% to 54.54% and increased in the increased PA from 58.06% to 60.29%. In the increased PA group children more frequently than standard PA ate vegetables, fruits, fish, poultry meat, wholemeal bakery products, milk, dairy products and drinking tea without sugar, as well as ate breakfast. The standard PA children more frequently than increased PA ate high sugar and/or fat content food as sweets, savoury snacks and drank fizzy drinks as well as fast foods. The frequency of often undertaken leisure time PA increased in the increased PA group from 67% to 74%, while decreased in the standard PA from 58% to 52%. (4) Conclusions: Increase in organized PA at school beneficially influenced early adolescents’ eating behaviour and frequency of leisure time PA during 2 years observation. It also increased early adolescents’ awareness of healthy diet. Increased PA at school helps shaping healthy lifestyle among early adolescents.
... Beberapa penelitian menunjukkan bahwa dehidrasi mempunyai pengaruh buruk pada atlet. Kehilangan cairan 1-2% dari berat tubuh dapat menimbulkan kehausan yang berarti, rasa tidak nyaman, peningkatan denyut jantung, serta turunnya penampilan atlet sebesar 10% (Dieny, F. F., & Putriana, 2015) (Hoch, A. Z., Goossen, K., & Kretschmer, 2008). Hilangnya cairan 3-5% dari massa tubuh bisa menyebabkan mulut kering, gemetar berlebihan, aktifitas fisik melambat, lesu, muntah, emosi tidak stabil, dan penurunan performa sebesar 30% (Amstrong, 2007) ...
Dalam olahraga beladiri sangat dibutuhkan kualitas teknik dan kondisi fisik yang baik, agar membuat permainan yang dilakukan berlangsung secara baik dan maksimal tanpa adanya kesalahan kekurangan dalam mengkondisikan tubuh untuk melakukannya. Untuk menghindari terjadinya dehidrasi setelah selesai berolahraga sangat diperlukan minuman yang berisotonik dan berelektrolit, kandungan minuman isotonik adalah karbohidrat dan elektrolit. Tujuan penelitian ini untuk mengetahui bagaimana hubungan status hidrasi dengan vo2max pada atlet karate. Metode dalam penelitian ini menggunakan motode penelitian korelasional, sampel dalam penelitian menggunakan teknik total sampling. Instrumen yang digunakan dalam penelitian ini adalah Tes Urin menggunakan PURI dan Bleep Test dengan jarak 20 meter kepada sampel penelitian 8 orang atlet karate tako forki Bengkalis. Hasil penelitian mengungkapkan terdapat hubungan status hidrasi dengan vo2max pada Atlet Karate Tako Forki Bengkalis. Dimana nilai rhitung=0,969>rtabel=0,707 pada taraf signifikansi α=5%. Dalam olahraga karate konsumsi cairan yang cukup saat latihan maupun saat bertanding juga menjadi faktor yang mempengaruhi performa atlet. Semakin baik tingkat status hidrasi seorang atlet maka akan semakin baik pula daya tahan atlet tersebut. Hasil penelitian diharapkan mampu menjadi rujukan untuk memperhatikan konsumsi cairan yang cukup untuk performa atlet saat latihan maupun bertanding
... It helps to improve athletic performance by dwindling fatigue as well as disease and injury threats. Besides, it also empowers the athletes to enhance practice and speedy recovery (Hoch et al. 2008). Further, poor nutritional status can lead to growth failure or poor body dimensions in young players, which can also lead to dismal performance. ...
Badminton is a fast shuttle-racquet game, which requires adequate endurance and agility for hitting shots. For consistent and superior performances, players need to develop decent nutritional status and tremendous physical fitness. The present study concerns with the effect of anthropometric indices and nutritional profiles on arm strength for racquet gripping. Adolescent male (N=100) and female (N=100) badminton players aged 10 to 15 years were selected from Nagpur, India, and arm anthropometric indices and skeletal muscles of the players were determined by tape and bioelectrical impedance analyzer respectively. Muscle growing macronutrient (protein) and skeletal developing micronutrients (calcium and phosphorus) were calculated from dietary data for consecutive 3 days by the 24-hour dietary recall method. Arm strength was appraised from the hand grip strength test. Statistically, the assessed data were tested at 1% and 5% significance levels. Pearson correlation coefficients were derived. All the age groups possessed substantially shorter arm lengths (2.41-15.43%) than reference standards. Older groups appeared to have greater arm circumferences (1.00-3.92 cm) than younger groups. Overall, boys showed elevated skeletal muscles (6.69% and 8.29%) than girls. Dietary protein and phosphorus ingestion were significantly higher (45.42-90.88% and 16.18-40.62%) than recommended dietary allowances (RDAs). Calcium intake (23.26-28.48%) was below the RDA. Older male players performed under excellent grade (38%) in the hand grip strength test, depicting masculine supremacy. Positive correlations (r= 0.0710 to 0.5947) between arm anthropometry and nutrient intake with grip strength proved their affirmative effects on delivering various explosive shots, which can enhance the performance level of emerging young players.
... geliştirerek, hastalık ve sakatlık riskini azalmak ayrıca fiziksel aktivite sonrası toparlanma sürecini hızlandırmak için gereklidir (9). Enerji alımı ile harcaması arasındaki denge, enerji eksikliğinden korumaktadır. ...
Bu çalışma, adölesan voleybol oyuncularının beslenme bilgi düzeyleri, beslenme durumları ile sıvı tüketimlerine beslenme eğitiminin etkisinin saptanması amacıyla planlanmıştır. Araştırma, Türkiye Voleybol Federasyonu bünyesindeki TVF Proje takımında oynayan yaşları 15-17 arası olan 13 erkek profesyonel voleybol oyuncusu ile yapılmıştır. Araştırma kapsamında çalışmaya katılan adölesan sporculara 4 hafta boyunca haftada bir saat, sağlıklı beslenme ve sporcu beslenmesi konularında eğitim verilmiştir. Eğitimlerden önce çalışmaya katılan adölesan sporculardan genel bilgi alınmıştır. Sporculara eğitim öncesinde ve sonrasında besin tüketim sıklığı ve beslenme bilgi düzeyi formu ile 2 günlük fiziksel aktivite kayıt formu uygulanmıştır. Aynı şekilde eğitim öncesi ve sonrası olmak üzere voleybolcuların vücut ağırlığı ve boy uzunlukları ölçülmüştür. Ayrıca voleybolcuların vücut yağ yüzdeleri, vücut yağ kütleleri, yağsız doku kütleleri ve vücut sıvı kütleleri biyoelektirik impedans cihazı ile ölçülmüştür. Çalışmaya katılan voleybolcuların yaş ortalamaları 16.4±0.77 yıldır. Sporcuların profesyonel olarak voleybol oynama süreleri ortalama 5±3.54 yıldır. Voleybolcuların eğitim öncesi ortalama (Beden Kütle İndeksi) BKİ'leri 21.8±1.70 kg/m2 iken, eğitim sonrası 22.8±1.85 kg/m2 olarak değişmiştir (p<0.05).Voleybolcuların eğitim öncesi ortalama vücut yağ yüzdeleri %11.8±4.52 iken, eğitim sonrası %11.7±4.41 olarak değişmiştir (p>0.05). Sporcuların eğitim öncesi ortalama yağsız doku kütleleri 70.4±5.19 kg iken, eğitim sonrası 71.2±5.63 kg olarak değişmiştir (p>0.05). Voleybolcuların ortalama günlük total enerji gereksinimleri Harris-Benedict denklemine göre 3108.2±240.7 kkal, Schofield denklemine göre 3188.4±257.10 kkal olarak bulunmuştur. Voleybolcuların eğitim öncesi karbonhidratlardan gelen enerji yüzdeleri ortalama %47±6.59 iken eğitim sonrası %42.2±5.04 olarak bulunmuştur (p<0.05). Sporcuların eğitim öncesi ortalama protein alımları 108.1±41.08 g iken eğitim sonrası 136.1±29.73 g olarak saptanmıştır (p<0.05). Voleybolcuların enerjinin proteinden gelen oranlarının ortalaması eğitim öncesi %15.3±3.64 iken, eğitim sonrası %18.8±2.37 olarak belirlenmiştir (p<0.05). Sporcuların eğitim öncesi ortalama sükroz alımları 76.0±50.86 g iken eğitim sonrası 52.6±33.32 g'a azalmıştır (p<0.05). Eğitim öncesi fruktoz alımları da 21.2±13.89 g iken eğitim sonrası 12.9±6.29 g olarak belirlenmiştir (p<0.05). Eğitim sonrası ortalama B2, niasin ve B12 vitamini alımları artmıştır (p<0.05). Voleybolcuların süt ve süt ürünleri grubundan tükettikleri besinlerin ortalama miktarları eğitim öncesi 522.6±409.18 g iken eğitim sonrası 861.0±356.25 g olarak belirlenmiştir (p<0.05). Sporcuların et, balık, tavuk ve kurubaklagil grubundan tükettikleri besinlerin ortalama miktarları eğitim öncesi 155.0±75.06 g iken eğitim sonrası 202.3±53.11 g olarak artmıştır (p<0.05). Sporcuların ortalama su tüketimleri eğitim öncesi 1769.0±897.23 ml iken eğitim sonrası 2369.2±534.58 ml olarak artmıştır (p<0.05). Voleybolcuların beslenme bilgi düzeyi sorularına verdikleri doğru cevap sayısı eğitim öncesi 8.2±2.16 iken, eğitim sonrası 12.6±2.17'dir (p<0.05). Sonuç olarak 4 hafta boyunca haftada bir saat verilen beslenme eğitimi, adölesan voleybol oyuncularının beslenme bilgi düzeylerini anlamlı şekilde artırmış, besin tüketimlerinin olumlu yönde değişmesini sağlamıştır. Anahtar kelimeler: Adölesan, voleybol, beslenme, beslenme bilgi düzeyi, beslenme eğitimi Bu çalışma için Başkent Üniversitesi Tıp ve Sağlık Bilimleri Araştırma Kurulu tarafından KA16/339 nolu ve 30/11/2016 tarihli 'Etik Kurul Onayı' alınmıştır.
This study was planned to determine the effect of nutrition education program on nutrition knowledge, nutrition status and fluid intake of adolescent volleyball players. Research was conducted with 13 male professional volleyball players aged between 15 and 17, who were participant of TVF Project team in Turkish Volleyball Federation. Within the scope of the research, nutrition education including healthy diet and sport nutrition subjects, is provided to adolescent volleyball players for 1 hour per week along 4 weeks as an intervention. Before the intervention, general information related to the participants was collected. Before and after the intervention, food consumption frequency questionnaire, nutrition knowledge assessment and two-day physical activity form were applied by the researcher. Volleyball players' body weight and height ware measured. In the same way, body fat percentage, body fat mass, fat free mass and body water mass of the adolescent volleyball players were measured with bioelectrical impedance device. Mean age of the volleyball players was 16.46±0.776 years. As professionals, the players had been playing volleyball for 5±3.54 years in average. While the players' mean BMI was 21.8±1.70 kg/m2, after the intervention, it changed to 22.8±1.85 kg/m2 (p<0.05). Before the intervention, mean body fat percentage of the players was %11.8±4.52 and it changed to %11.7±4.41 after the intervention (p>0.05). While mean fat free mass of the players was 70.4±5.19 kg, it changed to 71.2±5.63 kg after the intervention. According to Harris-Benedict equation, mean energy requirement of the players was 3108.2±240.7 kcal and according to Schofield equation, it was 3188.4±257.10 kcal. It was found that the players' mean percentage of energy arising from carbohydrates was %47±6.59 before the intervention and that it was %42.2±5.04 after the intervention (p<0.05). It was detected that the mean protein intake of the players was 108.1±41.08 g before the intervention and that it was 136.1±29.73 g (p<0.05) after the intervention. While the players' mean percentage of energy arising from protein was %15.3±3.64, it was determined that it was %18.8±2.37 after intervention (p<0.05). It was designated that the players mean sucrose intake was 76.0±50.86 g before the intervention, and that it decreased to 52.6±33.32 g after the intervention (p<0.05). It was determined that the players' fructose intake was 21.2±13.89 g before the intervention, and it was 12.9±6.29 g after the intervention (p<0.05). While average niacin, B12, and B2 intake of the volleyball players increased when compared to before intervention (p<0.05). Average amount of dairy products that the volleyball players consumed was 522.6±409.18 g before the intervention and it increased to 861.0±356.25 g (p<0.05). It was designated that average amount of consumed nutrition from meat, fish, chicken and legume groups was 155.0±75.06 g before the intervention and it was 202.3±53.11 g after the intervention (p<0.05). While the average water intake of the players was 1769.0±897.23 ml before the intervention, it increased to 12.6±2.17 (p<0.05). As a result, providing 4-week nutrition education for one hour per week significantly increased nutrition knowledge of the adolescent volleyball players and it led dietary intake of the players to change in a positive way. Keywords: Adolescent, volleyball, nutrition, nutrition knowledge, nutrition education KA16/339 numbered and 30/11/2016 dated 'Ethics Committee Approval' is received by Başkent University Medical and Health Sciences Research Council.
... In this case, the need for adequate energy and nutrient intakes becomes especially important for young athletes [3]. In young athletes, it is difficult to make general recommendations for nutritional needs as their energy needs change significantly depending on age, growth and development levels [4]. ...
... Hasil penelitian ini sesuai dengan penelitian sebelumnya yang menemukan adanya hubungan positif antara nilai VO2Max dengan status gizi, baik dalam kondisi gizi normal maupun malnutrisi (8). Selain itu, penelitian pada atlet di Training center Jakarta terlihat bahwa semakin tinggi indeks massa tubuh maka akan semakin rendah VO2Max (9). Setiap kenaikan IMT sebesar 1 kg/m 2 diikuti dengan penurunan VO2Max sebesar 1,30 ml/kgBB/menit. ...
Prestasi atlet ditentukan salah satunya oleh performa. Kenyataannya banyak atlet mengalami penurunan stamina dalam waktu yang singkat saat pertandingan. Faktor gizi dan hidrasi atlet sangat berpengaruh dalam mencapai prestasi. Pemain sepakbola seharusnya memiliki indeks massa tubuh normal, komposisi tubuh antara massa otot dan lemak yang proporsional. Tujuan penelitian ini menganalisis profil asupan, status gizi, hidrasi dan performa atlet. Penelitian observasional dengan desain cross-sectional di Sekolah Sepak Bola (SSB) Semarang. Besar sampel sebanyak 111 atlet yang dipilih melalui metode consecutive sampling. Variabel dependen adalah performa atlet yang dinilai berdasarkan VO2Max yang diukur menggunakan metode multistage. Variabel independen adalah status gizi, asupan energi, makronutrien, zat besi, kalsium, asupan cairan dan status hidrasi. Status Gizi dinilai berdasarkan IMT, persen lemak tubuh, dan lingkar pinggang. Data asupan dan c presentase perubahan berat badan. Uji korelasi Spearman dan regresi linear ganda digunakan dalam analisis. Hasil penelitian menunjukkan ada hubungan antara indeks massa tubuh (p=0,007; r=0,254), persen lemak tubuh (p=0,001; r=0,317), asupan energi (p=0,021; r=0,218), asupan protein (p=0,029; r=0,207), asupan lemak (p=0,018; r=0,224), asupan zat besi (p=0,003; r=0,276), asupan cairan sehari (p=<0,001; r=0,397), asupan cairan sebelum latihan (p==0,02; r=0,22) dan status hidrasi berdasarkan % selisih berat badan (p=0,049; r=0,188) dengan skor VO2Max. simpulan penelitian ini adalah Persen lemak tubuh, asupan cairan sehari, dan lingkar pinggang sangat berhubungan dengan skor VO2Max. Kata kunci: status gizi; profil asupan; asupan cairan; status hidrasi; VO2Max
... Sports nutrition improves athletic performance because it reduces fatigue and the risk of illness and injury [66]. It also allows athletes to optimize their training and recover faster [15,66]. During confinement, it is essential to balance energy intake and expenditure to prevent an energy deficit or surplus. ...
Coronavirus 2019 (COVID-19) is an infectious viral disease that has spread globally, resulting in the ongoing pandemic. Currently, there is no vaccine or specific treatment for COVID-19. Preventive measures to reduce the chances of contagion consist mainly of confinement, avoiding crowded places, social distancing, masks, and applying strict personal hygiene as recommended by the World Health Organization (WHO). After the first wave of infection in many countries, the potential effects of relaxing containment and physical distancing control measures suggest that as a result of these measures, a second wave of COVID-19 appears probable in these countries. In sport, the period of self-isolation, and quarantine, for COVID-19 affects the physical preparation of athletes as well as their mental health and quality of life to an even greater extent (i.e., nutrition, sleep, healthy lifestyle), and thus, relevant and practical recommendations are needed to help alleviate these physical and mental health concerns. Our review aims to summarize the physiological and psychological effects of detraining associated with athletes' confinement during the proposed second wave of COVID-19. This article also proposes answers to questions that concern the advantages and disadvantages of different types of social media platforms, the importance of nutrition, and the effects of sleep disturbance on the health and modified lifestyle of athletes during this worldwide pandemic. Thus, this review provides some general guidelines to better manage their modified lifestyle and optimally maintain their physical and mental fitness with respect to measures taken during this restrictive proposed second wave of the COVID-19 confinement period.
... Sport nutrition enhances athletic performance by decreasing fatigue and the risk of disease and injury; it also enables athletes to optimize training and recover faster (Hoch, et al., 2008). It is very important to balance the energy expenditure with the energy intake in order to prevent the energy deficit or excess. ...
Introduction. Proper nutrition is crucial for child and adolescent athletes to maintain growth and development and to achieve optimal results in sports. It is very important to balance the energy expenditure with the energy intake in order to prevent the energy deficit or excess.
Materials and methods. Subjects involved in two different sports participated in the study: 13 gymnasts (age 13.8 ± 4.1 years, height 153.4 ± 11.3 cm, weight 47.1 ± 10.5 kg) and 15 basketball players (age 15.5 ± 1.1 years, height 176.7 ± 7.9 cm, weight 65.2 ± 10.7 kg). Determination of total energy expenditure was made by prediction equations. The subjects maintained a food records for 5 consecutive days, which were processed in the ASA24 system of the NCI.
Results and discussion. Energy intake in both groups is sufficient to meet the daily needs, development of young athletes and provide the energy needed in training. The intake of three minerals (calcium, magnesium and potassium) and three vitamins (D, E and A) was lower than recommended values in both groups.
Conclusion. As a result of the busy schedule of adolescent athletes, their main meals are out of home, and the proportion of highly processed foods containing small amounts of important vitamins and minerals is high. The main recommendations include dairy products, fruits, vegetables and whole grains. The idea behind the changes is to give young athletes the right diet and the right eating habits.
... An excellent food source that contains appropriate amounts of both macroand micronutrients is therefore essential in order to provide for the energy and nutrition needs of athletes, sportspeople, and others with active lifestyles. Date bars could fulfil this requirement under sports nutrition, as such bars may enhance athletic performance by reducing fatigue and the risk of disease and injury as well as enable athletes to optimize training and recover faster [60]. The centrepiece goal of virtually all athletes is to balance energy intake with energy expenditure in order to prevent an energy deficit or an excess of it [61]. ...
... Selain itu, atlet remaja memiliki risiko dehidrasi lebih tinggi daripada atlet dewasa. 19,20 Atlet remaja berisiko kehilangan cairan saat berolahraga disebabkan oleh produksi panas tubuh lebih tinggi dan lebih mudah menyerap panas karena mempunyai rasio permukaan tubuh yang lebih besar dibandingkan atlet dewasa sehingga simpanan cairan yang ada di dalam tubuh digunakan untuk menurunkan panas tubuh. 20 Berdasarkan penelitian pada atlet sepak bola, sebagian besar atlet mengonsumsi cairan yang kurang saat latihan maupun pertandingan. ...
Latar Belakang : Atlet sepak bola merupakan atlet yang melakukan olahraga dengan intensitas tinggi. Atlet sepak bola berpotensi untuk mengalami dehidrasi apabila kehilangan cairan karena peningkatan pengeluaran air melalui keringat dan pernafasan tidak diimbangi dengan konsumsi cairan yang cukup. Atlet remaja memiliki risiko dehidrasi lebih tinggi daripada atlet dewasa. Tujuan penelitian ini untuk menganalisis hubungan konsumsi cairan pada periode latihan dengan status hidrasi setelah latihan pada atlet sepak bola remaja.Metode : Penelitian observasional dengan desain cross-sectional yang melibatkan 47 atlet sepak bola remaja laki-laki (usia 13-16 tahun) di Sekolah Sepak Bola Universitas Diponegoro Semarang. Subjek dipilih dengan simple random sampling. Data yang dikumpulkan meliputi karakteristik subjek, konsumsi cairan, kehilangan berat badan, volume urin, keringat yang hilang selama latihan dan status hidrasi setelah latihan. Latihan pertandingan sepak bola dilakukan selama 70 menit. Konsumsi cairan pada periode latihan diukur dengan menggunakan food recall, keringat yang hilang selama latihan dihitung menggunakan rumus dan status hidrasi setelah latihan diketahui dengan pemeriksaan berat jenis urin. Hasil : Rerata konsumsi cairan pada periode latihan (1678,77±457,99 ml) masih kurang dari kebutuhan (2400-3400 ml). Rerata keringat yang hilang adalah 1364,19±448,68 ml. Semua atlet sepak bola remaja mengalami dehidrasi, sebagian besar mengalami significant dehydration (89,4%) dan yang lain mengalami minimal dehydration (10,6%). Terdapat hubungan yang bermakna antara konsumsi cairan pada periode latihan dan status hidrasi setelah latihan (p<0,05), tetapi tidak terdapat hubungan antara keringat yang hilang selama latihan dan status hidrasi setelah latihan pada atlet sepak bola remaja (p>0,05).Simpulan : Terdapat hubungan yang bermakna antara konsumsi cairan pada periode latihan dan status hidrasi setelah latihan pada atlet sepak bola remaja.
... According to several studies adolescence athlete has higher risk than adult because there is a lot of fat in their body and contains only 20% water. [2,3,6] Besides, adolescence has high risk to have dehydration due to higher body heat generation and higher ability to absorb heat because they have higher body surface ratio compare to adult athlete so that the body liquid inside their body is utilized to decrease the heat [6]. In average soccer athlete lose 1.59% of body weigh during their practice in hot environment [7]. ...
... Indeed, nutrition quality is vital for providing energy and achieving good health and physical performance. It is important to acquire enough nutrients to allow children to meet their needs for growth and tissue maintenance, which will altogether allow them to meet the metabolic demands of PA, especially with regard to vigorous PA [40]. ...
Physical activity, body mass, and dietary habits are known to be important determinants of overall health status, but there is an evident lack of studies that examine these issues specifically in preschool children. The aim of this study was to identify associations that may exist between adhering to the Mediterranean diet (MD), levels of physical activity (PA), and body composition indices in apparently healthy preschool children from southern Croatia. Participants were 5-to 6-year-old preschoolers from the Mediterranean part of the country (the Split-Dalmatia County; n = 260, 126 females). Adherence to the MD was observed by the Mediterranean Diet Quality Index (KIDMED), PA level was evaluated by the Preschool-age Children's Physical Activity Questionnaire (Pre-PAQ), and responses were collected from the parents. The participants' waist circumferences (in cm), waist-to-hip ratios, and body mass index (in kg/m 2 , and in a z-score calculated relative to the normative value for age and sex) were used as indicators of body composition. All children were of the same age and tested over a one-month period of the same year as a part of the regular examination undertaken before attending elementary school. With only 6% of the children having a low KIDMED score, adherence to the MD was high. MD adherence was higher in girls (Chi-square = 15.31, p < 0.01) and children who live on the coast of the Adriatic Sea (Chi-square = 18.51, p < 0.01). A mixed effects logistic regression (with kindergarten as random factor) identified sedentary activity to be negatively associated with MD adherence (OR per point: 0.65, 95% CI: 0.44-0.91). High adherence to the MD in the studied sample may be attributed to regulated feeding in kindergarten. Considering that most Croatian elementary schools do not provide food to their students, MD adherence should be investigated later in life and also in other parts of the country where the MD is culturally less prevalent.
... Diet refers to the use and collection of such type of food ingredients which allow growth and maintain the various physiological functions of the body [3]. Use of diet depends upon the age, sex and nature of activity performing by a person. ...
... Nutrition and Dietary is recommended as an important part of sport performance for young athletes [1]. Nutrition is increasingly recognized as a key component of optimal sporting performance, with both the science and practice of sports nutrition developing rapidly [2], Sports nutrition enhances athletic performance by decreasing fatigue and the risk of disease and injury; it also enables athletes to optimize training and recover faster [3]. To optimize performance, young athletes need to learn what, when and how to eat and drink before, during and after activity [1]. ...
Purpose: The purpose of this study was to determine the ultimate body mass, performance, and nutritional characteristics of the Algerian judo junior athletes, and also analysing the impact of nutritional intakes on stabilising Weight loss according to special performance of judo athletes. Material: Twenty-one male university athletes (aged: 21.45 ± 1.32; height: 1.81 ± 0.45 m; and body mass: 73.9 ± 4.1 kg) participated in this study during a period of stabilising Weight loss before and after 15 days of caloric restriction. Athletes were submitted to anthropometrical measurements and performed the Special Judo Fitness Test. Values for nutrient intakes were obtained from a 15 day food record kept during a training camp period of Weight maintenance and after a 15-day caloric restriction. Results : caloric restriction resulted in significant decreases in body mass (73.73 ± 2.1) and performance. However, Special Judo Fitness Test index increased significantly (14.00 ± 1.75) during caloric restriction in comparison to stabilising Weight loss. Conclusion: Exercise and caloric restriction lead to determine the ultimate Weight and physical performance. The present study provides baseline nutritional data that can be used in the prescription of individual training programs for university judo Athletes.
... Nutrition and Dietary is recommended as an important part of sport performance for young athletes [1]. Nutrition is increasingly recognized as a key component of optimal sporting performance, with both the science and practice of sports nutrition developing rapidly [2], Sports nutrition enhances athletic performance by decreasing fatigue and the risk of disease and injury; it also enables athletes to optimize training and recover faster [3], To optimize performance, young athletes need to learn what, when and how to eat and drink before, during and after activity [1]. [4] propose that high quality Weight loss is often of importance to elite athletes in order to maintain their muscle (engine) and shed unwanted fat mass, potentially improving athletic performance Judo is an intermittent combative sport requiring technical, tactical, and psychological skill that creates great muscle-strength and -power demands on both the upper and lower body [5]. ...
Purpose:The purpose of this study was to determine the ultimate body mass, performance, and nutritional characteristics of the Algerian judo junior athletes, and also analysing the impact of nutritional intakes on stabilising Weight loss according to special performance of judo athletes. Material:Twenty-one male university athletes (aged: 21.45 ± 1.32; height: 1.81 ± 0.45 m; and body mass: 73.9 ± 4.1 kg) participated in this study during a period of stabilising Weight loss before and after 15 days of caloric restriction. Athletes were submitted to anthropometrical measurements and performed the Special Judo Fitness Test. Values for nutrient intakes were obtained from a 15 day food record kept during a training camp period of Weight maintenance and after a 15-day caloric restriction.Results:caloric restriction resulted in significant decreases in body mass (73.73 ± 2.1) and performance. However, Special Judo Fitness Test index increased significantly (14.00 ± 1.75) during caloric restriction in comparison to stabilising Weight loss.Conclusion:Exercise and caloric restriction lead to determine the ultimate Weight and physical performance. The present study provides baseline nutritional data that can be used in the prescription of individual training programs for university judo Athletes.
... Of langur tími getur liðið ef börn borða ekkert milli hádegisverðar í skólanum og kvöldverðar heima og slíkt kemur baeði niður á árangri og líðan í íþróttum, auk þess að geta heft eðlilegan vöxt og þroska barna (Petrie, Stover og Horswill, 2004). Máltíð sem borðuð er fyrir aefingu aetti að vera kolvetnarík og auðmeltanleg en að aefingu lokinni er aeskilegt að neyta blöndu af kolvetnum og próteinum til að stuðla að endurheimt, vexti og viðhaldi (Hoch, Goossen og Kretschmer, 2008;Purcell, Canadian Paediatric Society og Paediatric Sports & Exercise Medicine Section, 2013). Í svörum foreldra kom meðal annars fram að börnin kaemu oft mjög svöng og orkulaus heim af aefingum. ...
Food environment in youth sports - Research project (Article in Icelandic, English abstract available).
The aim of the study was to observe food choices among 10-18 year old children and the food environment of their sports club, Ungmennafélagið Afturelding (UMFA), located in the municipality of Mosfellsbær. The municipality has been a pioneer as a health promoting community since 2013. The approach aimed to gain insight into how the food environment of the sports center can impact food choices of children in sports and also to explore parents’ and children’s perception of food and drinks available at the center.
... In our study, athletes adolescents consumed 57% of carbohydrates (a mean of 6.23 g/kg/day). This proportion was lower than that recommended for athletes under growing process and daily practice, to maximize muscular glycogen storage, carbohydrates should comprise 45% to 65% of total energy intake for 4-to 18-year-olds [27], in average of 6 to 10g/kg/day [28]. So, Anderson et al [29] suggested that although professional Soccer players readily achieve current guidelines for daily protein and fat intake, carbohydrates intake on the day before and in recovery from match play was not in accordance with guidelines to promote muscle glycogen storage. ...
... Beberapa penelitian menunjukkan bahwa dehidrasi memiliki efek negatif terhadap performa olahraga. 17,18 Kehilangan cairan 1-2% dari berat tubuh dapat menyebabkan rasa haus yang kuat, kehilangan cita rasa, perasaaan tidak nyaman, peningkatan denyut jantung, dan penurunan performa olahraga sebesar 10%. 9,19,20 Kehilangan cairan 3-5% dari berat tubuh dapat menyebabkan mulut kering, rasa tidak sabar, penurunan volume darah, sulit konsentrasi, gemetar berlebihan, aktifitas fisik melambat, lesu, muntah, emosi tidak stabil, dan penurunan performa sebesar 30%. ...
Latar Belakang : Salah satu unsur gizi yang penting adalah air. Atlet remaja memiliki risiko dehidrasi lebih tinggi daripada atlet dewasa. Tidak semua atlet sepak bola memiliki status hidrasi yang baik sebelum latihan, apalagi keringat yang keluar terus menerus selama pertandingan yang tidak diimbangi dengan konsumsi cairan yang cukup akan berpengaruh terhadap terjadinya kelelahan, dehidrasi dan akhirnya berdampak pada performa atlet
Tujuan : menganalisis hubungan status hidrasi sebelum latihan, dan konsumsi cairan selama periode latihan dengan status hidrasi setelah latihan pada atlet sepak bola remaja.
Metode : Penelitian penelitian ini dilakukan dengan desain cross-sectional, populasi adalah atlet mudadi sekolah sepak bola (SSB) UNDIP Semarang. Pemilihan 47 subjek dilakukan dengan acak subjek penelitian berjumlah 47 atlet yang dipilih secara acak. Latihan yang dilakukan adalah permainan sepak bola selama 70 menit. Data identitas subjek diperoleh melalui wawancara menggunakan kuesioner. Data status gizi melalui perhitungan indeks massa tubuh. Konsumsi cairan pada periode latihan (sebelum, selama dan setelah latihan), diperoleh melalui pengamatan dan wawancara menggunakan food recall, dan status hidrasi diketahui dengan pemeriksaan berat jenis urin (BJU).
Hasil : Usia atlet berkisar 13-16 tahun. Sebagian besar atlet kurang mengkonsumsi cairan selama latihan (80,9% atlet) maupun setelah latihan (89,4% atlet). Rerata konsumsi cairan pada periode latihan (1678,77+457,9 ml) lebih rendah dari kebutuhan yang dianjurkan (2400-3400 ml). Hanya 1 atlet (2,1%) yang terhidrasi baik sebelum latihan, 68,8% mengalami significant dehydration. Sedangkan setelah latihan seluruh atlet mengalami dehidrasi, yaitu 89,4% significant dehydration, dan 10,6% minimal dehydration. Ada hubungan konsumsi cairan pada periode latihan (r=-0,297, p=0,043) dan status hidrasi sebelum latihan (r=0,392, p=0,006) dengan status dehidrasi setelah latihan pada atlet sepak bola remaja
Simpulan : status hidrasi sebelum latihan , konsumsi cairan pada periode latihan berhubungan dengan status hidrasi setelah latihan pada atlet sepak bola remaja.
... Diet refers to the use and collection of such type of food ingredients which allow growth and maintain the various physiological functions of the body[3]. Use of diet depends upon the age, sex and nature of activity performing by a person. ...
The present review study was an effort to assess the perception of various researchers (Available
in the form of literature) regarding the causes, sign, symptoms, and effects of malnutrition on
human health. Various research articles congregated for the purpose to review the perceptions
of different researchers regarding the causes, sign and symptoms and effects of malnutrition
on the health of children. After study the perception of different researchers available in the
form of literature, the researcher arrived at conclusion that unbalance diet, psychological
problems, digestive syndromes and stomach conditions etc all are the causes of malnutrition.
It also concluded by the researcher from the available literature, that loss of fat, difficulty in
respiration, and complication during surgery are the main sign and symptoms of malnutrition.
Furthermore, under nutrition can lead the body toward weakness and over nutrition lead the
body toward obesity.
... The combination of various demands, such as the increased need for nutrient intake due to the accelerated pubertal development, the need to maintain a low body mass (and indirectly fat mass), the potentially long-term, poor in nutrients and possibly low energy intake (chronic malnutrition), and the intense hours of daily training requirements (without adequate nutritional intake) expose young athletes to growth disorders, long-term nutritional deficiencies, emotional problems, menstrual disorders (amenorrhea), premature fatigue, eating disorders, osteopenia and a particularly high risk of injuries (Caine, Russell, & Lim, 2013;Desbrow et al., 2014;Hoch, Goossen, & Kretschmer, 2008;Meyer & Manore, 2011). All these disorders are central to the pathogenesis of the "female athlete triad", whose main components are: reduced energy availability (with or without eating disorders), menstrual dysfunction and decreased bone density (osteopenia). ...
Pre-adolescent and adolescent gymnasts, and especially artistics gymnasts (AG) and rhythmic gymnasts (RG), belong to a high risk group for severe deficiency in /lack of basic nutrients, especially calcium, iron, folic acid, vitamin D and zinc. The increased demands of accelerated pubertal development in combination with the need to maintain a reduced body mass and the intense daily training (without energy recovery and adequate rest) expose particularly the younger athletes to growth disorders, long-term nutritional deficiencies, problems of emotional nature (low self-esteem, dissatisfaction with body image, multiple daily weighing, obsessions with body aesthetics and physical appearance), hormonal disorders (amenorrhea), premature fatigue, osteopenia, and a particularly increased risk of injury. The vast majority of athletes feel that they are on a constant (chronic) diet. It is typical for athletes to spend hours of daily training with only water intake and no other snack, and coaches are aware of this. The detection and diagnostic assessment of nutritional deficiencies / shortcomings and future nutritiondependent disorders during the developmental ages of a gymnast is a field of study for every qualified sport dietician. Keeping this in mind, the purpose of this review is to provide targeted nutritional support directions to elite athletes of AG and RG with priority and emphasis on strengthening the immune system, nutritional strategy for direct energy recovery and the control of timely daily food intake during the annual training season.
... A carbohydrate based, low-fat meal should be eaten 1-3 h prior to sport to ensure adequacy of glycogen stores and availability of carbohydrate for exercise (106). In the case of elite athletes, it may be preferable to have a meal 4 hours prior to activity to maximize glycogen stores and to help ensure only basal insulin is acting. ...
... En conclusión, en pacientes con défi cit nutricionales ya sea malnutrición u obesidad, es necesario enfatizar la monitorización y el cuidado del estado nutricional. [4][5][6] Para realizar la evaluación nutricional en el niño y adolescente no se recomienda el uso rutinario del IMC ya que no discrimina si el aumento de peso es por masa muscular o grasa. Lo que se recomienda es la medición del porcentaje de grasa corporal a través del pliegue cutáneo junto con bioimpedanciometria o densitometría. ...
Notre étude avait pour objectif d’évaluer l’énergie apportée par les aliments consommés par les adolescents de l’école congolaise de Basket-ball (GAMETIME) pendant la période d’entrainement et comparer ces apports aux normes recommandées par les nutritionnistes. Une enquête de consommation alimentaire a été menée auprès de 10 joueurs dont l’âge moyen était de 15,03 ± 3,65 ans. Le poids moyen était de 41,57 ± 5,18kg, tandis que la taille moyenne des sujets était de 1,69 ± 0,09m. La méthode utilisée était celle de rappel de 24 heures. Les résultats ont indiqué que 70% des sujets prennent 2 repas par jour et ces repas sont constitués de déjeuner (60%) et du diner (30%). Toutefois, l’apport nutritionnel trouvé était de 3717,12 kilocalories. Tandis que la dépense énergétique était estimée à 2827,29 ±128,87 kilocalories. Par ailleurs, les pourcentages des apports étaient respectivement de 68,95 % en glucides (˃ à 60 %), de 19,52 % en lipides (< à 30 %) et de 11,53 % en protides (< à 15 %). Cependant, les apports énergétiques trouvés étaient supérieurs aux dépenses énergétiques, soit une différence de 889,83 ± 3,38 kilocalories a été constatée. La balance énergétique était plus dominée par des apports que des dépenses. Ces apports répondaient superficiellement aux normes recommandées. En conclusion, l’apport en macronutriment a montré des pourcentages incohérents par rapport aux normes recommandés. L’alimentation des basketteurs adolescents congolais était non seulement hyper glucidique mais malheureusement hypo lipidique et hypo protéique. Ces macronutriments déséquilibrés sont considérés comme facteurs limitants de performance. Our study aimed to evaluate the energy provided by the foods consumed by adolescents from the Congolese basketball school (GAMETIME) during the training period and to compare these contributions to the standards recommended by nutritionists. A food consumption survey was conducted among 10 players whose average age was 15.03 ± 3.65 years. The average weight was 41.57 ± 5.18 kg, while the average height of the subjects was 1.69 ± 0.09 m. The method used was the 24 hour callback. The results indicated that 70% of the subjects took 2 meals per day and these meals consisted of lunch (60%) and dinner (30%). However, the nutrient intake found was 3717.12 kilocalories. While the energy expenditure was estimated at 2827.29 ± 128.87 kilocalories. In addition, the percentages of intakes were respectively 68.95% in carbohydrates (˃ to 60%), 19.52% in lipids (<30%) and 11.53% in proteins (<15%). However, the energy intake found was greater than the energy expenditure, a difference of 889.83 ± 3.38 kilocalories was observed. The energy balance was more dominated by intakes than expenditures. These contributions superficially met the recommended standards. In conclusion, the macronutrient intake showed inconsisten percentages compared to the recommended standards. The diet of Congolese adolescent basketball players was not only high in carbohydrates but unfortunately low in fat and low in protein. These imbalanced macronutrients are considered as performance limiting factors.
The focus of this research study was to assess the perception of athletes about diet and its role in the maintenance of performance. The target population of this research study was comprised of all the players of different sports clubs of District Bannu. Two hundred and six (206) players were randomly selected as sample of the study. For the collection of data, the researcher developed a closed form of questionnaire. The developed questionnaire personally served by the researcher among the respondents and collected back after getting it filled by the respondents. The collected data were tabulated and analyzed by using percentage and mean average as statistical tool. After data analysis, the researcher arrived at conclusion that proper diet is the basic requirement of athletic performance. The data also revealed that carbohydrates, protein, fats, vitamins, minerals and water are more important to consume in proper amount for sports participation. 1. BACKGROUND OF THE STUDY According to Hoch etal.(2008) The term diet refers to the collection of such type of food which helps to improve the physical condition, control weight and helps to cure diseases by making the immune system strong. Similarly, Khan (2014) defines the sports diet as the diet, which need by athlete before, during and after the activity. The author further says that sports diet helps the athlete to maintain the performance while participating in sporting events. Every athlete need to use proper diet before, during and after the activity. Lacking of proper diet not only adversely affects the performance of athlete but it significantly affects the overall functional capacity of the body of athlete (Khan, 2014). Sports diet has been one of the basic needs of every sportsmen participating at various level of sports. According to Hoch etal.(2008) Sports diet enhances athletic performance by decreasing fatigue and the risk of disease and injury; it also enables athletes to optimize training and recover faster. Athletes must fuel their bodies with the appropriate nutritional foods to meet their individual energy requirements in competition, training and recovery. If these nutritional needs are not met, there is an increased risk of poor performance and health issues. Sports diet is a strong and valuable tool for promoting the athletic performance. It is an energy source for our body, which gives us to "get up and go." Without sports diet an athlete, remain unable to show and to maintain performance during the competition. For the maintenance of performance a player need to used different nutrients such as carbohydrates, protein, and fats etc. (Coyle, 1995) Sports diet must be consist of food nutrients, which are more beneficial such as according to Litte (2004) Carbohydrates should be the largest percentage of an athlete calorie intake, at least 50% to 60% in his food. This helps to meet with the demands of energy needed during exercise, maintain blood glucose and refill muscle glycogen stores. According to Lemon (1998) Protein is required for the hormone and enzyme production, nutrient transfer in the blood, connective tissue support, and the repair of tissue in response to periods of exercise. They should consume 10%-15% of total calories from protein. Similarly Cotugna, Vickery, & McBee (2005) stated that Fats intake is important for the energy production, protecting organs, providing insulation to the body, and facilitating fat-soluble vitamin uptake and essential fatty acid intake. Food components may be classified as macronutrients and micronutrients. It is necessary for athlete to use both macronutrients and micronutrients. Lacking of both macronutrients and micronutrients may cause the poor or week performance of athlete during the competition (Khan,2014) Macronutrients are essential for players in energy production, bone health, immune function and antioxidant activity. Micronutrient itself does not provide energy but helps to maintain the functional capacity of the body of athlete (Maughan, King & Lea, 2004). Sports diet has been one of the basic needs of every sportsmen participating at various level of sports. Sports diet has the variety of benefits for maintenance and improvement of performance for an athlete. The performance of sportsmen is decreasing day by day. There may be many reasons behind this decreasing standard. Diet is one of the basic requirements for sportsmen. How much diet is necessary for athlete and is sufficient diet is provided to athlete before, during and after the competition? For the purpose to discover the fact the researcher, intend to conduct a research study under the title "Diet and Sports Performance"
Purpose
Nutrition has been increasingly recognized as a key component to optimal sports performance. Though several botanical agents have been reported to possess ergogenic potential, there exists a great interest for tasty and safe natural substances as performance boosters. In the present contribution, the ergogenic potential of a novel powder form of coconut inflorescence sap (CSP) was investigated for the first time.
Method
Out of the fourteen participants recruited, twelve recreationally active men completed the single-blinded, placebo-controlled, crossover study for 8 weeks. Running based anaerobic sprint test (RAST) and 2.4 km running test were performed as anaerobic and aerobic tests, respectively. In arm 1, the participants were received with either placebo (200 mL water containing 400 mg aspartame/day) or CSP (3 g in 200 mL water/day) for 21 days. After the washout period, arm 2 was performed with a reversed treatment regime. VO2 max was estimated using a predictive formula.
Results
The primary outcome showed a significant enhancement in peak power and mean power (peak power from 3.67 W/kg b. wt. to 5.38 W/kg b. wt.; mean power from 3.47 W/kg b. wt. to 5.06 W/kg b. wt.). A significant (p < 0.001) increase in VO2 max among CSP condition compared to the placebo was observed (from 59.38 ± 2.15 mL/kg/min to 62.56 ± 0.52 mL/kg/min). Further, serum analysis revealed enhanced antioxidant status and reduced lactate dehydrogenase (p < 0.01) levels without any significant changes (p > 0.05) in safety parameters.
Conclusion
It was concluded that CSP possesses significant ergogenic effect and may find wide application as a natural ingredient for sports nutrition and energy drinks.
Trail Registration
The study was approved by the ethical committee (Reg. No ECR/184/Indt/KA /2014, dated 15/07/2014).
Günümüzde milyonlarca insan farklı amaçlar doğrultusunda yükseltiye
çıkmaktadırlar. Rekreasyonel faaliyetler, yüksek irtifa tırmanışları ve sportif
performansı artırmak bu amaçlardan bazılarıdır. Yüksek irtifanın organizma
üzerinde ki etkilerine yönelik çalışmalara 1878 yılında başlanılmış ise de;
yüksek irtifa konusu 1968 yılında yapılan Mexico olimpiyatları ile sporda en
önemli konulardan biri haline gelmiştir. Sporcuların performansını etkileyen
temel faktörlerin başında genetik yapı, uygun antrenman ve beslenme ilkeleri
gelmektedir. Sporcuların ve antrenörlerin, uygun enerji alımı ve enerji kullanımının
zihinsel ve kas fonksiyonlarını ne kadar arttırdığını anlamaları oldukça
önemlidir. Beslenme, sporcuların bilgi sahibi oldukları takdirde kontrol altında
tutabilecekleri ve performanslarını etkileyen en önemli etkenlerden birisidir.
Sporcu beslenmesi son yıllarda üzerinde çok fazla çalışma yapılan ve gittikçe de
dikkat çekmeye başlayan bir bilim dalı olup, spor bilimcilerinin olduğu kadar;
sporcuların, antrenörlerin, kondisyonerlerin, sporcu ailelerinin ve spor ile ilgili
tüm meslek mensuplarının bilgi sahibi olması gereken bir konudur. Bu kitap
bölümünde ise beslenmenin daha özel bir konusu olan yüksek irtifada beslenme
alışkanlıkları ve ilkelerini incelemek amacıyla ele alınmıştır.
Çalışmanın amacı, çağımızın en büyük sorunlarından birisi olan obezitenin, yeme bozukluğu ile ilişkisini ve altında yatan psikolojik nedenleri araştırmaktır. İnsan vücudu bedensel, zihinsel ve ruhsal yönden bir bütündür. Yeme bozukluğu ile ilgili sorumlu tutulan diğer nedenler ise sosyalleşme, kültür, teknolojik gelişmeler ve çevresel faktörlerdir. Yemenin psikolojik boyutu duygusal açlık kavramıyla açıklanmaktadır. Duygusal yeme ve açlığın nedeni bilinçaltı süreçlerle açıklanmaktadır. İnsanların duyguları sıkışıp kaldığında, vereceği kararlar bu duyguların etkisinde olmaktadır. Duygusal açlık, fiziksel açlıktan yani gerçek açlıktan bağımsız, içgüdüsel dürtülerin etkisiyle yeme isteğinin olmasıdır. Geçmişte yaşanmış bastırılmış ve üstesinden gelinmeyen duygulardan kaynaklandığı düşünülmektedir. Duygusal yemeye öfke, stres, kızgınlık, yalnızlık, hayal kırıklığı, boşlukta hissetme, affedememe, güvensizlik, korku, kırgınlık, olumsuz beden algısı gibi duygular neden olmaktadır. Duygusal açlık ruhsal bir durumdur ve bir davranış bozukluğudur. Çözümünde yanlış davranışın yerine doğru davranışın konulması gerekmektedir. Psikoterapi, meditasyon, davranış terapisi, egzersiz ve bazen de ilaç kullanmak gerekebilir. Yeme bozukluğu ile ilgili bazı hastalıklar vardır. anoreksiya nevroza, tıkınırcasına yeme ve bulimia nevrozadır. Bunlara genellikle depresyon eşlik etmektedir. Kültürel değişimin etkisiyle, atalarımızın sağlıklı beslenme düzeninden uzaklaşıp, modern çağın beslenme şekline geçilmesi, besin değeri düşük enerjisi yüksek gıdaların tüketilmesi, teknolojik gelişmeler sonucu hareketsiz yaşam tarzının normalleşmesi, insan sağlığını fiziksel ve ruhsal açıdan tehdit etmektedir. Sonuç olarak; obezite, psikolojik açlık ve yeme bozukluğunun ruhsal boyutu göz ardı edilmemelidir.
Davranışın arkasındaki duygusal nedenleri açıklığa kavuşturmak, problemin çözümüne yardımcı olacaktır.
Adolesan dönem (12-18 yaş), çocukluk ile erişkin çağ arasındaki biyolojik
ve fizyolojik değişikliklerin en hızlı olduğu gelişme dönemidir. Adolesan
dönemde seks steroidlerinin salgılanması, büyüme hormonunun salgılanmasını
tetikler. Büyüme hormonu salınımının artması, büyüme atağının oluşmasına yol
açar. Kemik gelişiminin oldukça hızlı olduğu bu dönemde bireyin tüm yaşamını
etkileyecek sakatlık ve yaralanmaların yaşanmaması oldukça önemlidir. Özellikle
egzersiz esnasında oldukça dikkatli olunmalıdır. Gereğinden fazla yapılan ağırlık
çalışmaları adolesan dönemde büyümeyi olumsuz etkiler. Bu dönemde zihinsel
ve fiziksel süreçleri etkileyen önemli etkenlerin başında spor ve beslenme gelmektedir.
Beslenme büyüme ve gelişmenin sağlanması, sağlıklı olma ve enerji
gereksiniminin sağlanması için önemlidir. Sporcu beslenmesi ise sportif performansın
geliştirilmesi, hastalık ve sakatlık riskini azaltmak ve fiziksel aktivite
sonrası toparlanma sürecini hızlandırmak açısından oldukça önemlidir. Düzenli
bir egzersiz ile birlikte yeterli ve dengeli beslenme, sporcu performansını olumlu
etkilemekle beraber gelecekte oluşabilecek sağlık problemlerinin riskini azaltmaktadır.
Adolesan dönemde sağlıklı bir gelişim ve iyi bir sportif performans için
yeteri oranda karbonhidrat, protein ve sıvı tüketilmesi oldukça önemlidir. Yeterli
ve dengeli beslenen sporcuların, iyi beslenmeyen sporculara göre daha yüksek
performans, yüksek antrenman etkinliği, artmış konsantrasyon ve dikkat, düşük
sakatlanma ve hastalık oranı, uygun vücut kompozisyonu ve yeterli büyüme ve
gelişme avantajına sahip oldukları söylenebilir. Yeterli ve dengeli beslenme, sporcuların
performans gelişimini garanti etmemektedir, sadece yetersiz ve dengesiz
beslenmenin ortaya çıkaracağı olumsuz etkileri ortadan kaldırır. Bundan dolayı
adolesan dönemde beslenme; hem sportif başarının sağlanması için hem de büyüme
ve gelişmenin devamlılığının sağlanması için çok önemlidir.
Objectives:
Hypertension is a common and important problem in kidney transplant recipients, directly affecting graft and patient survival. Here, we evaluated the relationship between renal-cardiac damage and peripheral and central aortic blood pressure levels in renal transplant recipients.
Materials and methods:
We measured peripheral blood pressure (office, daytime ambulatory, and central aortic) in 46 kidney transplant recipients. Biochemical parameters were simultaneously measured. Electrocardiography and echocardiography were performed. Patients with office blood pressure > 140/90 mm Hg or who were treated with antihypertensive drugs were accepted as hypertensive.
Results:
Ambulatory blood pressure measurements were higher than office blood pressure measurements (at 135.6/85.6 mm Hg vs 121.8/77.5 mm Hg in hypertensive and at 118.8/77.6 mm Hg vs 101.6/62.5 mm Hg in normotensive patients) (P < .05). There were 40 hypertensive and 6 normotensive kidney transplant recipients according to ambulatory blood pressure measurement and 33 hypertensive and 13 normotensive according to office blood pressure measurements. Central aortic pressure measurements were significantly higher in hypertensive patients versus office or ambulatory blood pressure (P = .045 and .048, respectively). Left ventricle mass index and proteinuria were significantly correlated with central aortic pres sure (P = .015, r = 0.358 and P = .022, r = 0.499, respectively) and nonsignificantly correlated with peripheral blood pressure measurements (P > .05). Left ventricle hypertrophy was found to be less common in patients using angiotensin-converting enzyme, although not significantly (P > .05).
Conclusions:
In kidney transplant recipients, blood pressure should be monitored with ambulatory blood pressure measurements, even when normal office pressure levels are shown. The aim of antihypertensive therapy is not only to decrease brachial artery pressure but also to keep central aortic systolic blood pressure in the proper interval, adjusted according to age. This may more effectively prevent the development of renal cardiac damage versus peripheral blood pressure measurement monitoring.
The 1970s was an important era for the growth of sports opportunities for women. It was also during this period that there was an increase in the number of laboratories focusing on both exercise physiology and sports nutrition. Initially, studies focused mainly on endurance sports and the nutritional status of male participants. Results showed that what an athlete consumed before, during, and after exercise could help to improve performance [1]. The importance of studying both male and female athletes is better recognized today because there are significant differences. For example, food portions, nutrient requirements, and metabolic rates often differ between females and males.
Children and adolescents who participate in intense sports training may face physical and psychologic stresses. The pediatric health care provider can play an important role in monitoring an athlete's preparation by obtaining a proper sports history, assessing sleep hygiene, discussing nutrition and hydration guidelines, and evaluating physiologic causes of fatigue. Educating parents and athletes on the potential risks of high-intensity training, inadequate rest and sleep, and a poor diet may improve the athlete's performance and prevent symptoms of overtraining syndrome. Infectious mononucleosis must also be considered a cause of fatigue among adolescents. The signs and symptoms of overtraining and burnout are discussed in this article. [Pediatr Ann. 2016;45(3):e91-e96.].
Latzka, William A., Michael N. Sawka, Scott J. Montain, Gary S. Skrinar, Roger A. Fielding, Ralph P. Matott, and Kent B. Pandolf.Hyperhydration: thermoregulatory effects during compensable exercise-heat stress. J. Appl. Physiol. 83(3): 860–866, 1997.—This study examined the effects of hyperhydration on thermoregulatory responses during compensable exercise-heat stress. The general approach was to determine whether 1-h preexercise hyperhydration [29.1 ml/kg lean body mass; with or without glycerol (1.2 g/kg lean body mass)] would improve sweating responses and reduce core temperature during exercise. During these experiments, the evaporative heat loss required (E req = 293 W/m ² ) to maintain steady-state core temperature was less than the maximal capacity (E max = 462 W/m ² ) of the climate for evaporative heat loss (E req /E max = 63%). Eight heat-acclimated men completed five trials: euhydration, glycerol hyperhydration, and water hyperhydration both with and without rehydration (replace sweat loss during exercise). During exercise in the heat (35°C, 45% relative humidity), there was no difference between hyperhydration methods for increasing total body water (∼1.5 liters). Compared with euhydration, hyperhydration did not alter core temperature, skin temperature, whole body sweating rate, local sweating rate, sweating threshold temperature, sweating sensitivity, or heart rate responses. Similarly, no difference was found between water and glycerol hyperhydration for these physiological responses. These data demonstrate that hyperhydration provides no thermoregulatory advantage over the maintenance of euhydration during compensable exercise-heat stress.
Background Since the passage of The Dietary Supplement Health and Education Act in 1994, there has been a flood of new "dietary" supplements promoting anti-aging benefits such as the enhancement of growth hormone or testosterone levels. Androstenediol and androstenedione are such products. This study's purpose was to elucidate the physiological and hormonal effects of 200 mg/d of oral androstenediol and androstenedione supplementation in men aged 35 to 65 years while participating in a 12-week high-intensity resistance training program. Methods Fifty men not consuming any androgenic-enhancing substances and with normal total testosterone levels, prostate-specific antigen, hemoglobin, and hematocrit, and with no sign of cardiovascular or metabolic diseases participated. Subjects were randomly assigned to a placebo, androstenediol (diol), or androstenedione (dione) group using a double-blind study design. Main outcomes included serum sex hormone profile, body composition assessment, muscular strength, and blood lipid profiles. Results During the 12 weeks of androstenedione or androstenediol use, a significant increase in the aromatization by-products estrone and estradiol was observed in both groups ( P = .03). In the dione group, total testosterone levels significantly increased 16% after 1 month of use, but by the end of 12 weeks, they returned to pretreatment levels. This return to baseline levels resulted from increases in aromatization and down-regulation in endogenous testosterone synthesis based on the fact that luteinizing hormone was attenuated 18% to 33% during the treatment period. Neither androstenediol nor androstenedione enhanced the adaptations to resistance training compared with placebo for body composition or muscular strength. However, both androstenediol and androstenedione supplementation adversely affected high-density lipoprotein cholesterol (HDL-C) levels, coronary heart disease risk (representing a 6.5% increase), and each group's respective (low-density lipoprotein cholesterol [LDL-C]/HDL-C)/(apolipoprotein A/apolipoprotein B) lipid ratio (diol: +5.2%; dione: +10.5%; P = .05). In contrast, the placebo group's HDL-C levels increased 5.1%, with a 12.3% decline in the (LDL-C/HDL-C)/(apolipoprotein A/apolipoprotein B) lipid ratio. These negative and positive lipid effects occurred despite no significant alterations in body composition or dietary intakes in the supplemental groups or placebo group, respectively. Conclusions Testosterone precursors do not enhance adaptations to resistance training when consumed in dosages recommended by manufacturers. Testosterone precursor supplementation does result in significant increases in estrogen-related compounds, dehydroepiandrosterone sulfate concentrations, down-regulation in testosterone synthesis, and unfavorable alterations in blood lipid and coronary heart disease risk profiles of men aged 35 to 65 years.
There is still debate in the literature on whether or not endurance athletes tend to have low iron stores. In this article, we propose that endurance athletes really are at risk of becoming iron deficient due to an imbalance between absorption of dietary iron and exercise-induced iron loss. The purpose of this article is to present a critical review of the literature on iron supplementation in sport. The effect of iron deficiency on performance, its diagnosis and suggestions for treatment are also discussed.
Studies of the nutritional status of athletes in various disciplines have shown that male, but not female, athletes clearly achieve the recommended dietary intake of iron (10 to 15 mg/day). This reflects the situation in the general population, with menstruating women being the main risk group for mild iron deficiency, even in developed countries. Whereas the benefit of iron supplementation in athletes with iron deficiency anaemia is well established, this is apparently not true for non-anaemic athletes who have exhausted iron stores alone (prelatent iron deficiency); most of the studies in the literature show no significant changes due to supplementation in the physical capacity of athletes with prelatent iron deficiency. However, the treatment protocols used in some of these studies do not meet the general recommendations for the optimal clinical management of iron deficiency, that is, with respect to adequate daily dosage, mode of administration and treatment period. For future studies, we recommend a prolonged treatment period (≥3 months) with standardised conditions of administration (use of a pharmaceutical iron preparation with known high bioavailability and a dosage of ferrous (Fe++) iron 100 mg/day, taken on an empty stomach).
Currently, decisions regarding iron supplementation are best made on the basis of taking care of individual athletes. We believe that there are sufficient arguments to support controlled iron supplementation in all athletes with low serum ferritin levels. Firstly, the development of iron deficiency is prevented. Secondly, the nonspecific upregulation of intestinal metal ion absorption is reverted to normal, thus limiting the hyperabsorption of potentially toxic lead and cadmium even in individuals with mild iron deficiency.
Objective.
—To evaluate the effect of calcium supplementation on bone acquisition in adolescent white girls.
Context
Androstenedione, a precursor to testosterone, is
marketed to increase blood testosterone concentrations as a natural
alternative to anabolic steroid use. However, whether androstenedione
actually increases blood testosterone levels or produces anabolic
androgenic effects is not known.Objectives
To determine if short- and long-term oral
androstenedione supplementation in men increases serum testosterone
levels and skeletal muscle fiber size and strength and to examine its
effect on blood lipids and markers of liver function.Design and Setting
Eight-week randomized controlled trial
conducted between February and June 1998.Participants
Thirty healthy, normotestosterogenic men (aged 19-29
years) not taking any nutritional supplements or androgenic-anabolic
steroids or engaged in resistance training.Interventions
Twenty subjects performed 8 weeks of
whole-body resistance training. During weeks 1, 2, 4, 5, 7, and 8, the
men were randomized to either androstenedione, 300 mg/d
(n=10), or placebo (n=10). The effect
of a single 100-mg androstenedione dose on serum testosterone and
estrogen concentrations was determined in 10 men.Main Outcome Measures
Changes in serum testosterone and estrogen
concentrations, muscle strength, muscle fiber cross-sectional area,
body composition, blood lipids, and liver transaminase activities based
on assessments before and after short- and long-term androstenedione
administration.Results
Serum free and total testosterone concentrations were not
affected by short- or long-term androstenedione administration. Serum
estradiol concentration (mean [SEM]) was higher (P<.05) in
the androstenedione group after 2 (310 [20] pmol/L), 5 (300 [30]
pmol/L), and 8 (280 [20] pmol/L) weeks compared with
presupplementation values (220 [20] pmol/L). The serum estrone
concentration was significantly higher (P<.05) after 2 (153
[12] pmol/L) and 5 (142 [15] pmol/L) weeks of androstenedione
supplementation compared with baseline (106 [11] pmol/L). Knee
extension strength increased significantly (P<.05) and
similarly in the placebo (770 [55] N vs 1095 [52] N) and
androstenedione (717 [46] N vs 1024 [57] N) groups. The increase of
the mean cross-sectional area of type 2 muscle fibers was also similar
in androstenedione (4703 [471] vs 5307 [604] mm2;
P<.05) and placebo (5271 [485] vs 5728 [451]
mm2; P<.05) groups. The significant
(P<.05) increases in lean body mass and decreases in fat
mass were also not different in the androstenedione and placebo groups.
In the androstenedione group, the serum high-density lipoprotein
cholesterol concentration was reduced after 2 weeks (1.09 [0.08]
mmol/L [42 (3) mg/dL] vs 0.96 [0.08] mmol/L [37 (3) mg/dL];
P<.05) and remained low after 5 and 8 weeks of training and
supplementation.Conclusions
Androstenedione supplementation does not increase
serum testosterone concentrations or enhance skeletal muscle
adaptations to resistance training in normotestosterogenic young men
and may result in adverse health consequences.
Figures in this Article
Androgenic-anabolic
steroids have been shown to enhance the gains in muscle size and
strength associated with resistance training.1- 4
Androstenedione, a precursor to testosterone, is normally produced by
the adrenal gland and gonads and is converted to testosterone through
the action of 17β-hydroxysteroid dehydrogenase, which is found in
most body tissues.5- 9 Androstenedione is also produced by
some plants and has recently been marketed as a product for increasing
blood testosterone concentrations to be used as a natural alternative
to anabolic steroid use.
However, the interconversions of androstenedione and testosterone to
other androgens, as well as to estrogens, are complex. In addition to
serving as a precursor to testosterone, androstenedione may be
converted into estrogens directly.10- 11 Since testosterone
is also aromatized to estradiol,11- 12 it is also possible
that increased production of testosterone following androstenedione
administration may also result in increased aromatization, which would
further attenuate any increase in the blood testosterone concentration.
These considerations raise the question of
whether androstenedione supplementation
increases the blood testosterone concentration and produces
anabolic-androgenic effects.
To date only one study has investigated the effect of oral
androstenedione administration on the blood testosterone
concentration.13 These authors observed 4- and 7-fold
increases in the blood testosterone concentration in 2 healthy women,
respectively, after the ingestion of a single dose of 100 mg of
androstenedione. The effect of androstenedione administration on blood
testosterone levels in healthy men is unknown. Therefore, one purpose
of this study was to determine whether short- and long-term
administration of oral androstenedione increases the blood
testosterone concentration and enhances gains in muscle size and
strength when combined with a resistance-training program.
Increased concentrations of testosterone in the blood have been
associated with an increased risk of cardiovascular disease, due both
to a lowering of the serum high-density lipoprotein cholesterol (HDL-C)
concentration and an increased serum concentration of low-density
lipoprotein (LDL) concentration.3,14- 19 Elevated blood
testosterone concentrations may also result in significant alterations
in liver function.20- 21 The effects on blood lipids and
liver function appear to be more pronounced in oral anabolic steroids,
compared with injectable agents. A second purpose of this study,
therefore, was to examine the effect of androstenedione administration
on blood lipids and on clinical markers of liver function.
It is the position of the American College of Sports Medicine that adequate fluid replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of fluid replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of fluid that should be ingested in preparation for, during, and after exercise or athletic competition:
1. It is recommended that individuals consume a nutritionally balanced diet and drink adequate fluids during the 24-h period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition.
2. It is recommended that individuals drink about 500 ml (about 17 ounces) of fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water.
3. During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated.
4. It is recommended that ingested fluids be cooler than ambient temperature[between 15° and 22°C (59° and 72°F)] and flavored to enhance palatability and promote fluid replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise.
5. Addition of proper amounts of carbohydrates and/or electrolytes to a fluid replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water.
6. During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g · h-1 to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising fluid delivery by drinking 600-1200 ml· h-1 of solutions containing 4%-8% carbohydrates (g · 100 ml-1). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin).
7. Inclusion of sodium (0.5-0.7 g · 1-1 of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of fluid. There is little physiological basis for the presence of sodium in an oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal.
Major sporting events in Malaysia are commonly staged in hot environments where the average daytime temperature is generally in the range of 29 to 31°C with the average relative humidity ranging from 80 to 95%. Exercise capacity and exercise performance are reduced when the ambient temperature is high and it has major implications for competitors as well as for spectators and officials. Prolonged exercise leads to progressive water and electrolyte loss from the body as sweat is secreted to promote heat loss. The rate of sweating depends on many factors and increases in proportion to work rate and environmental temperature and humidity. Sweat rates are highly variable and can exceed 2L.h-1 for prolonged periods in high heat. Since dehydration will impair exercise capacity and can pose a risk to health, the intake of fluid during exercise to offset sweat losses is important. Carbohydrate-electrolyte fluid ingestion during exercise has the dual role of providing a source of carbohydrate fuel to supplement the body's limited stores and of supplying water and electrolytes to replace the losses incurred by sweating. The composition of the drinks to be taken will be influenced by the relative importance of the need to supply fuel and water which, in turn depends on the intensity and duration of exercise activity, the ambient temperature, and humidity. Carbohydrate-electrolyte solutions appear to be more effective in improving performance than plain water. There is no advantage to fluid intake during exercise of less than 30-minute duration. Complete restoration of fluid balance after exercise is an important part of the recovery process and becomes even more important in hot, humid conditions. If a second bout of exercise has to be performed after a relatively short interval, the speed of rehydration becomes of crucial importance. Rehydration after exercise requires not only replacement of volume losses, but also replacement of some electrolytes, primarily sodium. Studies show that rehydration after exercise can be achieved only if sweat electrolyte losses as well as water are replaced. Drinks with low sodium content are ineffective at rehydration and they will only reduce the stimulus to drink. Addition of smalls amounts of carbohydrate to the rehydrating drinks may improve the rate of intestinal uptake of sodium and water and will improve palatability. The volume of the rehydration beverage consumed should be greater than the volume of sweat lost to provide the ongoing obligatory urine losses. Palatability of the beverage is a major issue when a large volume of fluid has to be consumed.
It has been estimated that as many as 250,000 adolescents are using anabolic steroids (AS). Recently, anecdotal reports suggest that athletes may also be using human growth hormone (HGH). The purpose of the present study was to determine the following: 1) if adolescents in two suburban midwestern high schools (83% white, 14% Asian, and 3% black) were using HGH; 2) knowledge of its effects; 3) reasons for use; and 4) concurrent AS use. After we obtained informed written consent, 224 male and 208 female 10th-grade students were surveyed using a 15-item questionnaire. Of male students surveyed, 5% (n = 11) reported past or present use of HGH, and one female student reported use. Our data suggest that among male adolescents surveyed, a majority had heard of this substance, and 31% of males reported knowing someone who was using HGH. Chi-square analysis found a significant association between AS and HGH use where seven AS users reported past or present use of HGH. Most HGH users were unaware of its side effects and reported first use between 14 and 15 years of age. No differences in sports activity, ethnicity, or age were found between users and nonusers of HGH.
Low glycemic index (GI) foods may confer an advantage when eaten before prolonged strenuous exercise by providing a slow-release source of glucose to the blood without an accompanying insulin surge. To test this hypothesis, eight trained cyclists pedalled to exhaustion one hour after ingestion of equal carbohydrate portions of four test meals: lentils, a low GI food (LGI); potato, a high GI food (HGI), and glucose and water. Plasma glucose and insulin levels were lower after LGI than after HGI from 30 to 60 min after ingestion (p less than 0.05). Plasma free fatty acid (FFA) levels were highest after water (p less than 0.05) followed by LGI and then glucose and HGI. From 45 to 60 min after ingestion, plasma lactate was higher in the HGI trial than in the LGI trial (p less than 0.05) and remained higher throughout the period of exercise. The rank order from lowest to highest for total carbohydrate oxidation during exercise was water, lentils, glucose and potato. Endurance time was 20 min longer after LGI than after HGI (p less than 0.05). These findings suggest that a low GI pre-game meal may prolong endurance during strenuous exercise by inducing less post-prandial hyperglycemia and hyperinsulinemia, lower levels of plasma lactate before and during exercise, and by maintaining plasma glucose and FFA at higher levels during critical periods of exercise.
Since the discovery of creatine in 1832, it has fascinated scientists with its central role in skeletal muscle metabolism. In humans, over 95% of the total creatine (Crtot) content is located in skeletal muscle, of which approximately a third is in its free (Crf) form. The remainder is present in a phosphorylated (Crphos) form. Crf and Crphos levels in skeletal muscle are subject to individual variations and are influenced by factors such as muscle fibre type, age and disease, but not apparently by training or gender. Daily turnover of creatine to creatinine for a 70kg male has been estimated to be around 2g. Part of this turnover can be replaced through exogenous sources of creatine in foods, especially meat and fish. The remainder is derived via endogenous synthesis from the precursors arginine, glycine and methionine. A century ago, studies with creatine feeding concluded that some of the ingested creatine was retained in the body. Subsequent studies have shown that both Crf and Crphos levels in skeletal muscle can be increased, and performance of high intensity intermittent exercise enhanced, following a period of creatine supplementation. However, neither endurance exercise performance nor maximal oxygen uptake appears to be enhanced. No adverse effects have been identified with short term creatine feeding. Creatine supplementation has been used in the treatment of diseases where creatine synthesis is inhibited.
It is clear that the anthropometric ramifications, especially with respect to muscle mass, of the metabolic actions of GH and IGF-I treatment in intact and GH-deficient adults require further study. At present, it appears that daily GH or IGF-I treatment modestly increases nitrogen retention in most normal adults, probably by separate but permissive mechanisms, but only for a short period of time (approximately 1 month). During prolonged GH administration, resistance to the anabolic actions of GH seems to occur, and optimizing the anabolic effects of GH or IGF-I treatment will require a better understanding of the interactions among GH, GHBP, IGF-I production, IGFBPs, the GH dose regimen, and other unidentified regulatory factors. On the basis of the similar increases in muscle protein synthesis, muscle cross-sectional area, and muscle strength observed in placebo and GH-treated exercising young adults, it is doubtful that the nitrogen retention associated with daily GH treatment results in an increase in contractile protein, improved muscle function, strength and athletic performance. Even in catabolic or GH-deficient populations, GH treatment provides only modest increments in nitrogen retention, muscle size, strength, and exercise capacity. Further, the side effects of GH treatment (water retention, carpal tunnel compression, insulin resistance) would be a detriment, rather than an aid, to athletic performance. In addition, whether prolonged (> 6 months) GH treatment alone or in combination with other agents used by athletes (e.g., anabolic steroids, beta-agonists) is associated with other adverse side effects (e.g., cancer, diabetes) has not been evaluated. Therefore, health professionals should continue to discourage the use of GH by exercise enthusiasts.
We evaluated the effects of self-selected diets on calcium absorption and calculated retention in girls during pre-, early, and late puberty. Dietary calcium absorption was measured in 51 girls aged 4.9-16.7 y by using a dual-tracer stable-isotope technique. We found that calcium intake was similar among girls of all ages and all degrees of pubertal development and was below the recommended dietary allowance (1200 mg/d) for 21 of 25 girls aged > or = 11 y. The early pubertal period was associated with a higher percent of dietary calcium absorption (34.4 +/- 11.9%) than was the prepubertal (27.7 +/- 8.2%) or late pubertal periods (25.9 +/- 7.8%). Calculated calcium retention averaged 132 +/- 83 mg/d in prepubertal girls, 161 +/- 88 mg/d in early pubertal girls, and 44 +/- 91 mg/d in late pubertal girls. Peak calcium retention during early puberty was far below that previously reported after higher calcium intakes. We conclude that peak periods for calcium retention for girls are in the pre- and early pubertal periods. The current calcium intake of American girls during the pubertal growth period may not enable maximal mineral retention; therefore, increased calcium intakes should be considered.
The effect of the glycemic index (GI) of postexercise carbohydrate intake on muscle glycogen storage was investigated. Five well-trained cyclists undertook an exercise trial to deplete muscle glycogen (2 h at 75% of maximal O2 uptake followed by four 30-s sprints) on two occasions, 1 wk apart. For 24 h after each trial, subjects rested and consumed a diet composed exclusively of high-carbohydrate foods, with one trial providing foods with a high GI (HI GI) and the other providing foods with a low GI (LO GI). Total carbohydrate intake over the 24 h was 10 g/kg of body mass, evenly distributed between meals eaten 0, 4, 8, and 21 h postexercise. Blood samples were drawn before exercise, immediately after exercise, immediately before each meal, and 30, 60, and 90 min post-prandially. Muscle biopsies were taken from the vastus lateralis immediately after exercise and after 24 h. When the effects of the immediate postexercise meal were excluded, the totals of the incremental glucose and insulin areas after each meal were greater (P < or = 0.05) for the HI GI meals than for the LO GI meals. The increase in muscle glycogen content after 24 h of recovery was greater (P = 0.02) with the HI GI diet (106 +/- 11.7 mmol/kg wet wt) than with the LO GI diet (71.5 +/- 6.5 mmol/kg). The results suggest that the most rapid increase in muscle glycogen content during the first 24 h of recovery is achieved by consuming foods with a high GI.
We determined the effect of the timing of glucose supplementation on fractional muscle protein synthetic rate (FSR), urinary urea excretion, and whole body and myofibrillar protein degradation after resistance exercise. Eight healthy men performed unilateral knee extensor exercise (8 sets/approximately 10 repetitions/approximately 85% of 1 single maximal repetition). They received a carbohydrate (CHO) supplement (1 g/kg) or placebo (Pl) immediately (t = 0 h) and 1 h (t = +1 h) postexercise. FSR was determined for exercised (Ex) and control (Con) limbs by incremental L-[1-13C]leucine enrichment into the vastus lateralis over approximately 10 h postexercise. Insulin was greater (P < 0.01) at 0.5, 0.75, 1.25, 1.5, 1.75, and 2 h, and glucose was greater (P < 0.05) at 0.5 and 0.75 h for CHO compared with Pl condition. FSR was 36.1% greater in the CHO/Ex leg than in the CHO/Con leg (P = not significant) and 6.3% greater in the Pl/Ex leg than in the Pl/Con leg (P = not significant). 3-Methylhistidine excretion was lower in the CHO (110.43 +/- 3.62 mumol/g creatinine) than P1 condition (120.14 +/- 5.82, P < 0.05) as was urinary urea nitrogen (8.60 +/- 0.66 vs. 12.28 +/- 1.84 g/g creatinine, P < 0.05). This suggests that CHO supplementation (1 g/kg) immediately and 1 h after resistance exercise can decrease myofibrillar protein breakdown and urinary urea excretion, resulting in a more positive body protein balance.
Competitive female athletes face many challenges unlike their recreationally active counterparts. As sport has advanced for girls and women, the physical, psychologic, and nutritional demands force female athletes to develop optimal strategies for competitive success. Sports medicine professionals must consume volumes of research investigating issues regarding competitive female athletes. This review focuses on three primary factors associated with females and performance: iron status, interrelated biorhythms, and energy optimization. Consideration of these factors in both health and performance goals is critical to the long-term success of competitive female athletes.
Dehydration by means of exercise, heat, diuretics, semistarvation, or a combination of these is common practice among competitors in weight class sports. Many studies have demonstrated a reduced aerobic work capacity following each of these forms of dehydration. The effects of these practices on performance that requires energy derived primarily from anaerobic sources is not well documented. The purpose of this study was to examine the effects of progressive, acute, thermal dehydration on performance of an anaerobic criterion task. Eleven collegiate wrestlers performed the Wingate Anaerobic Test (WAnT) prior to and after each of the following mean weight losses: 2%, 4%, and 5%. Weight loss was induced by passive thermal dehydration (56°C, 15% RH). Approximately 2 h were required in the environmental chamber to lose the required weight at each stage. There was no significant change (P > 0.05) in the ability to perform the WAnT or its various indices at any stage of dehydration, nor were blood lactate concentrations post WAnT significantly different from predehydration levels. This suggests that anaerobic performance may not be impaired to the extent that aerobic performance is by passive, thermal dehydration to a 5% body weight loss. However, deleterious physiologic effects may result from dehydration practices even though performance levels are maintained.
A quantitative approach to the regulation of the body's metabolism with its principal emphasis on the mechanism of thirst-motivation and water-metabolism. Harvard Book List (edited) 1944 #S20 (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Marshals known facts of growth and development of physical and reproductive systems, and the factors affecting them. Physiological, endocrinological, motor, and mental changes at adolescence are also covered. This edition deals with many aspects of growth at all ages. Contains bibliography. Harvard Book List (edited) 1964 #592 (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Nine volunteers have been examined during prolonged physical exercise to exhaustion at a load of about 60 per cent of W170. Ordinary circulatory parameters were measured as well as the quantities of glycogen, water and electrolytes in muscle tissue obtained by needle biopsy. In a separate study 6 subjects were examined for respiratory quotient under similar exercising conditions. The muscle glycogen fell considerably from a mean of 6.9 per 100g glycogen and fat-free solids to a mean of 1.7 g at the end of exercise. The quantity of muscle glycogen used was correlated both to total energy developed during exercise and also to duration of exercise.The electrolyte and water content in muscle tissue showed only small changes. Some increase was found in muscle sodium and chloride, and also in the chloride space. The potassium content fell significantly by about 4 per cent of the basal value. None of the circulatory parameters measured showed changes of such magnitude as to have a limiting effect on performance. Two subjects were examined also with glucose infusion during the exercise. The reduction of glycogen, as also the performance of these two subjects, was of the same order of magnitude with and without infusion of glucose. The results suggest that the capacity for prolonged work is directly correlated to the glycogen store in the working muscles.
Pseudoephedrine (PSE) is a readily available over-the-counter nasal decongestant which is structurally similar to amphetamine and is included on the International Olympic Committee's list of banned substances. However to date, little research has supported its putative ergogenic effect. This study investigated whether a 180 mg dose of PSE ingested 45 min prior to exercise enhanced short-term maximal exercise performance and/or altered related physiological variables.
A randomised, double-blind, crossover study in 22 healthy male athletes.
Maximum torque (mean +/- s.d., n = 22) produced in an isometric knee extension exercise was 321.1+/-62.0 Nm (PSE) and 295.7+/-72.4 Nm (placebo), and peak power obtained on the 'all-out' 30 s cycle test was 1262.5+/-48.5 W (PSE) and 1228.4+/-47.1 W (placebo) (P<0.01, P<0.03, respectively). Subjects were estimated to be producing 96.9+/-2.4% of their maximal possible isometric leg extension force after PSE ingestion, but only 95.3+/-2.4% when PSE was not ingested. Bench press tasks and total work during the cycle test were not affected by the ingestion of PSE. Lung function was altered following ingestion of PSE (P<0.05) with FEV1 and FVC significantly increased (P<0.02, P<0.01, respectively) although the FEV1/FVC ratio was not altered. Heart rate was significantly elevated by the ingestion of PSE immediately following the 30 s cycle sprint (P<0.01) however, lactate concentration was not altered by the ingestion of PSE.
The administration of a 180 mg dose of PSE increased maximum torque, produced in an isometric knee extension and produced an improvement in peak power during maximal cycle performance, as well as improving lung function.
It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. More marginal vitamin D deficiency is likely to be a significant contributing factor to osteoporosis risk. However, recent emerging data from studies of adults suggest that low vitamin D status (serum 25-hydroxyvitamin D levels <50 nmol/l) may be contributing to the development of various chronic diseases, including cardiovascular disease, hypertension, diabetes mellitus, some inflammatory and autoimmune diseases, and certain cancers. Adequacy of vitamin D status in children and adolescents has been the focus of a number of recent investigations, and these studies have shown a high prevalence of low vitamin D status during the winter (especially in adolescents), with lower prevalence during the summer. Therefore, consideration of potential corrective strategies to allow children and adolescents to maintain adequate vitamin D status throughout the year, even in the absence of adequate summer sun exposure, is warranted.
The purpose of this study was to compare the effects of short-term (12 wk) supplementation with androstenedione versus dehydroepiandrosterone (DHEA) on body composition, strength, and related hormones in middle-aged men.
A randomized, placebo-controlled, double-blind design was used to study 40 healthy, trained (>1 yr weight training) male subjects (mean +/- SD: age 48.1 +/- 3.9 yr; weight 79.8 +/- 9.8 kg). Subjects were randomly assigned to one of three groups: placebo (P), DHEA (D), or androstenedione (A). Supplements (50 mg capsules) were ingested two times daily for 12 wk. All testing, including venous blood samples, body composition, and performance, was conducted at three time points: presupplementation (1 d), at 6 wk, and postsupplementation (12 wk).
Despite a small increase in lean body mass (0.8 +/- 0.4 and 0.5 +/- 0.3 kg) and mean strength (6.8 +/- 2.7 and 5.7 +/- 2.4 kg) in both D and A groups respectively, these changes were not significantly different from P. In D, there was a significantly greater increase in DHEA-S levels than in P (P < 0.05). There were no adverse side effects demonstrated during D or A supplementation including significant changes in PSA, liver function, or lipid levels (P < 0.05).
The results of this study suggest that supplementation with 100 mg x d(-1) of either androstenedione or DHEA does not independently elicit a statistically significant increase in lean body mass, strength, or testosterone levels in healthy adult men over a 12-wk period.
To examine the effects of rapid dehydration on isometric muscular strength and endurance, seven men were tested at baseline (control) and after a dehydration (dHST) and a euhydration (eHST) heat stress trial. The dHST consisted of intermittent sauna exposure until 4% of body mass was lost, whereas the eHST consisted of intermittent sauna exposure (same duration as dHST) with water replacement. Peak torque was determined for the knee extensors and elbow flexors during three isometric maximal voluntary contractions. Time to fatigue was determined by holding a maximal voluntary contraction until torque dropped below 50% peak torque for 5 s. Strength and endurance were assessed 3.5 h after the HSTs (no food or water intake). Body mass was decreased 3.8+/-0.4% post dHST and 0.4+/-0.3% post eHST. Plasma volume was decreased 7.5+/-4.6% and 5.7+/-4.4%, 60 and 120 min post dHST, respectively. A small (1.6 mEq x L[-1]) but significant increase was found for serum Na+ concentration 60 min post dHST but had returned to predehydration level 120 min post dHST. Serum K+ and myoglobin concentrations were not affected by HSTs. Peak torque was not different (P > 0.05) among control, dHST, and eHST for the knee extensors (Mean (Nm)+/-SD, 285+/-79, 311+/-113, and 297+/-79) and elbow flexors (79+/-12, 83+/-15, and 80+/-12). Time to fatigue was not different (P > 0.05) among control, dHST and eHST for the knee extensors (Mean (s)+/-SD. 42.4+/-11.5, 45.3+/-7.6, and 41.8+/-6.0) and elbow flexors (48.2+/-8.9, 44.0+/-9.4, and 46.0+/-6.4). These results provide evidence that isometric strength and endurance are unaffected 3.5 h after dehydration of approximately 4% body mass.
Exercise is a well-known stress test for uncovering heart or lung disease, but it can also stress other organs and unmask a range of medical disorders. Practical case examples are given in seven areas: anemia, headache, hematuria, gastrointestinal problems, seizure, anhidrosis, and hypothyroidism. Recognizing the exercise-induced manifestations can lead to timely diagnoses that improve and save lives.
Competitive female athletes face many challenges unlike their recreationally active counterparts. As sport has advanced for girls and women, the physical, psychologic, and nutritional demands force female athletes to develop optimal strategies for competitive success. Sports medicine professionals must consume volumes of research investigating issues regarding competitive female athletes. This review focuses on three primary factors associated with females and performance: iron status, interrelated biorhythms, and energy optimization. Consideration of these factors in both health and performance goals is critical to the long-term success of competitive female athletes.
To examine the role of peak bone mass and subsequent postmenopausal bone loss in the development of osteoporosis and the reliability of identifying women at risk from one bone mass measurement and one biochemical assessment of the future bone loss.
Population based study.
Outpatient clinic for research into osteoporosis.
178 healthy early postmenopausal women who had participated in a two year study in 1977. 154 of the women underwent follow up examination in 1989, of whom 33 were excluded because of diseases or taking drugs known to affect calcium metabolism.
Bone mineral content of the forearm and values of biochemical markers of bone turnover.
The average reduction in bone mineral content during 1977-89 was 20%, but the fast losers had lost 10.0% more than had the slow loser group (mean loss 26.6% in fast losers and 16.6% in slow losers; p less than 0.001). Prediction of future bone mineral content using baseline bone mineral content and estimated rate of loss gave results almost identical with the actual bone mineral content measured in 1989. Seven women had had a Colles' fracture and 20 a spinal compression fracture. The group with Colles' fracture had low baseline bone mineral content (34.7 (95% confidence interval 31.3 to 38.1) units v 39.4 (38.1 to 40.8) units in women with no fracture) whereas the group with spinal fracture had a normal baseline bone mineral content (38.1 (35.0 to 41.1) units) but an increased rate of loss (-2.4 (-3.5 to -1.3)%/year v -1.8 (-2.1 to -1.5)%/year in women with no fracture).
One baseline measurement of bone mass combined with a single estimation of the rate of bone loss can reliably identify the women at menopause who are at highest risk of developing osteoporosis later in life. The rate of loss may have an independent role in likelihood of vertebral fracture.
The effects of gender on substrate utilization during prolonged submaximal exercise were studied in six males and six equally trained females. After 3 days on a controlled diet (so that the proportions of carbohydrate, protein, and fat were identical), subjects ran on a treadmill at a velocity requiring an O2 consumption of approximately 65% of maximal. They ran a total "distance" of 15.5 km with a range in performance time of 90-101 min. Plasma glycerol, glucose, free fatty acids, and selected hormones (catecholamines, growth hormone, insulin, and glucagon) were measured throughout and after the run by sampling from an indwelling venous catheter, and glycogen utilization was calculated from pre- and postexercise needle biopsies of vastus lateralis. Exercise protein catabolism was estimated from 24-h urinary urea nitrogen excretion over the test day and a nonexercise day. The males were found to have significantly higher respiratory exchange ratios (mean 0.94 vs. 0.87), greater muscle glycogen utilization (by 25%), and greater urea nitrogen excretion (by 30%) than the females. No gender differences were evident in the hormonal response to the exercise with the exception of a lower insulin concentration and a higher epinephrine concentration in the males. We conclude that, during moderate-intensity long-duration exercise, females demonstrate greater lipid utilization and less carbohydrate and protein metabolism than equally trained and nourished males.
This study determined the effects of consuming three different amounts of liquid carbohydrate 4 h before exercise on the metabolic responses during exercise and on exercise performance. Four hours before exercise subjects consumed either 45 (L) or 156 (M) g of carbohydrate in isocaloric feedings and either 0 (P) or 312 (H) g of carbohydrate. Interval cycling was undertaken for 95 min, followed by a performance trial. Blood glucose had reached basal 1 h after all feedings; blood insulin had reached basal 3 h after ingestion of P, L, and M but was still 84% higher for H at the start of exercise. During exercise insulin averaged 48% higher for H than P. Blood glucose decreased 16% during exercise for P, L, and M, whereas for H there was a transient drop the first 15 min of exercise, after which glucose increased and remained constant throughout exercise. More carbohydrate oxidation occurred during exercise for H vs P, whereas results were similar for L and M. Ingestion of H improved performance by 15% as compared with P, whereas performance was similar for L and M. These results indicate that, despite elevated insulin at the start of and during exercise, consumption of 312 g of carbohydrate 4 h before moderately intense prolonged exercise can improve performance, perhaps via an enhancement of carbohydrate oxidation.
Growth hormone is a powerful anabolic hormone that affects all body systems and plays an important role in muscle growth. It is released from the anterior pituitary in response to a variety of stimuli including exercise, sleep, stress, and the administration of a variety of drugs and amino acids. Serum levels are variable and are dependent on such factors as age, sex, body composition and level of fitness. Animal experiments have shown that growth hormone can partially reverse surgically induced muscle atrophy and weakness. Growth hormone administration to normal animals leads to muscle hypertrophy, but this muscular growth is not accompanied by increased strength. Growth hormone excess leads to acromegaly, a disease with significant morbidity, including a myopathy in which muscles appear larger but are functionally weaker. Although there is no scientific evidence documenting an improvement in athletic performance following growth hormone supplementation, it is reported that this practice is becoming more widespread among athletes wishing to avoid detection with current doping control measures. There are anecdotal reports that athletes are injecting cadaveric or biosynthetic forms of growth hormone, both of which are associated with potentially serious complications. In addition, some athletes are ingesting drugs and amino acids in the belief that their endogenous growth hormone secretion will be increased. There have been no scientific studies on the effects of growth hormone supplementation, and the anecdotal reports have been equivocal, with some individuals reporting spectacular results while others report no change. Despite the lack of valid evidence for its efficacy and its potentially serious side effects, it has been predicted that growth hormone use may increase. Growth hormone use and abuse has the potential to dramatically change the future conduct of athletics and may prove to be a threat to the concept of fair competition.
Six male college students were tested under two experimental conditions; amphetamine and no amphetamine. Each subject was tested three times under each condition. A double-blind placebo-controlled approach was employed and on six consecutive Fridays the subjects received either a placebo or 15 mg of Dexedrine per 70 kg of body weight 2 hours prior to testing. The physiological components tested were strength, muscular power, running speed, acceleration, aerobic power, and anaerobic capacity. Other variables evaluated were pre-exercise and maximum heart rates, respiratory exchange ratio and time to exhaustion. Data analysis revealed significant increases in knee extension strength, acceleration, anaerobic capacity, time to exhaustion, and pre-exercise and maximum heart rates. The most revealing results were in the area of increased time to exhaustion during the Vo2max test presumably due to higher lactic acid tolerance, thus a possible rationale to substantiate the theory that this drug has the ability to mask fatigue. It may also be possible that the biochemical actions of the drug alter fatigue processes directly. The results demonstrate that amphetamines have no effect on aerobic power, but further research will be necessary to clarify the drug's influence on muscular power-dominated movements.
Normal aging is characterized by detrimental changes in body composition, muscle strength, and somatotropic function. Reduction in muscle strength contributes to frailty and risk for fracture in the elderly. Although older adults increase muscle strength as a result of resistance exercise training, the strength gains quickly level off, with only modest increases thereafter despite continued training. To investigate whether age-related deficits in the somatotropic axis limit the degree to which muscle strength can improve with resistance training in older individuals, we conducted a double blind, placebo-controlled exercise trial. Eighteen healthy elderly men (65-82 yr) initially underwent progressive weight training for 14 weeks to invoke a trained state. Subjects were then randomized to receive either 0.02 mg/kg BW.day recombinant human GH (rhGH) or placebo, given sc, while undertaking a further 10 weeks of strength training. Sequential measurements were made of muscle strength (one repetition maximum), body composition (dual energy x-ray absorptiometry), and circulating levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3. For each exercise, strength increased for both groups (P = 0.0001) through 14 weeks of training, with little improvement thereafter. Increases in muscle strength ranged from 24-62% depending on the muscle group. Baseline plasma IGF-I concentrations were similar in both groups (mean +/- SEM, 106 +/- 9 micrograms/L), approximately half that observed in healthy young adults. In the rhGH group, IGF-I levels increased to 255 +/- 32 micrograms/L at week 15 and 218 +/- 21 micrograms/L at week 24 (P < 0.001). In the placebo group, IGF-I increased slightly to 119 +/- 6 micrograms/L at 24 weeks. IGF-binding protein-3 also increased in the rhGH group (P < 0.05). rhGH had no effect on muscle strength at any time, and no systematic difference in muscle strength was observed between groups throughout the study. Body weight did not change in either group, but lean body mass increased, and fat mass decreased (P < 0.05) in the rhGH group. Supplementation with rhGH does not augment the response to strength training in elderly men. These results suggest that deficits in GH secretion do not underlie the time-dependent leveling off of muscle strength seen with training in the elderly and provide no support for the popular view of GH as an ergogenic aid.
Athletes and researchers could benefit from a simple and universally accepted technique to determine whether humans are well-hydrated, euhydrated, or hypohydrated. Two laboratory studies (A, B) and one field study (C) were conducted to determine if urine color (Ucol) indicates hydration status accurately and to clarify the interchangeability of Ucol, urine osmolality (Uosm), and urine specific gravity (Usg) in research. Ucol, Uosm, and Usg were not significantly correlated with plasma osmolality, plasma sodium, or hematocrit. This suggested that these hematologic measurements are not as sensitive to mild hypohydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, Ucol was strongly correlated with Usg and Uosm. It was concluded that (a) Ucol may be used in athletic/industrial settings or field studies, where close estimates of Usg or Uosm are acceptable, but should not be utilized in laboratories where greater precision and accuracy are required, and (b) Uosm and Usg may be used interchangeably to determine hydration status.
The selection and utilisation of metabolic substrates during endurance exercise are regulated by a complex array of effectors. These factors include, but are not limited to, endurance training and cardiorespiratory fitness, exercise intensity and duration, muscle morphology and histology, hormonal factors and diet. Although the effects of these factors on substrate utilisation patterns are well understood, the variation in substrate utilisation during endurance exercise between males and females is not. Because of the extreme heterogeneity in exercise protocols and individuals studied, the differences in substrate utilisation between males and females remain somewhat inconclusive. Regardless of heterogeneity, if the results from studies are interpreted collectively, an apparent gender difference in the selection and metabolism of substrates can be seen in sedentary individuals. However, this difference between genders diminishes as the level of cardiorespiratory fitness is increased to that of highly trained individuals.
During rest and lower intensity exercise, the preferential metabolism of lipid occurs with a concomitant sparing of muscle glycogen. However, as the intensity of exercise is increased, the relative contribution of carbohydrate also increases. The exercise intensity at which the shift from lipid to carbohydrate is determined and regulated by the previously mentioned factors. Because the intensity and duration of exercise play a predominant role, the variation in exercise protocols poses a methodological concern when interpreting previous research.
When attempting to compare the metabolism of substrates during endurance exercise, appropriate selection and interpretation of measurement techniques are necessary. Measurement techniques include the nonprotein respiratory exchange ratio, muscle and fat biopsies and the measurement of various blood metabolites, such as free fatty acids and glycerol. Similarly, in vitro analysis of lipolytic activity has also been demonstrated in males and females in response to varying levels of female gonadotrophic hormones.
When comparing the substrate utilisation patterns between males and females, the area of hormonal regulation has received less attention. Often the catecholamine response to endurance exercise is measured; however, the gonadotrophic hormones, particularly those of the female, have received less attention when comparing genders. Indeed, the regulatory nature of the female gonadotrophic hormones has been demonstrated. Collectively, the effects of elevated estrogen, as in the luteal phase of menstruation, appear to promote lipolytic activity. Estrogen-mediated lipolytic activation occurs by apparently altering the sensitivity to lipoprotein lipase and by increasing the levels of human growth hormone (somatropin), an activator of lipolysis. Similarly, lipolytic activity appears to decrease under situations of lower estrogen levels (i.e. during the follicular phase of menstruation and in males). In addition, other cellular mechanisms which may influence substrate utilisation include the response of the insulin receptor to varying levels of female gonadotrophic hormones. Insulin binding capacity is decreased in response to elevated levels of estrogen.
Parallel to the regulatory effects of the female gonadotrophic levels is the menstrual status of endurance-trained females. When females progressively increase training volume, menstrual dysfunction becomes increasingly apparent. Thus, those females classified as endurance trained may vary in menstrual function from eumenorrhoeic to oligomenorrhoeic to ultimately amenorrhoeic. Since menstrual dysfunction may accompany endurance training, the circulating levels of female gonadotrophic hormones diminish to abnormally low levels. In response to subnormal levels of gonadotrophic hormones, the metabolism of energy substrates will probably change.
Additional areas that may influence substrate utilisation include muscle morphology and histology. However, differences in the metabolic selection of substrates between genders do not appear to be appreciably affected by these variables. In terms of fibre type distribution, muscle morphology is similar between males and females. Although males have a tendency to retain greater muscle fibre diameter, the overall fibre type distribution is comparable between similarly trained males and females. Males reportedly have slightly higher succinate dehydrogenase enzyme activity regardless of training status. However, malate dehydrogenase activity is similar between genders. Therefore, it appears that muscle enzyme activity is more affected by training status than by gender. Furthermore, when matched for cardiorespiratory fitness level, males and females show few appreciable differences.
When considering whether there are differences between males and females in terms of the selection and utilisation of metabolic substrates during exercise, numerous factors are involved: research methodology, training status, muscle morphology and histology, particularly endocrine function.
To evaluate the effect of calcium supplementation on bone acquisition in adolescent white girls.
A randomized, double-blind, placebo-controlled trial of the effect of 18 months of calcium supplementation on bone density and bone mass.
Ninety-four girls with a mean age of 11.9 + 0.5 years at study entry.
University hospital in a small town.
Calcium supplementation, 500 mg/d calcium as calcium citrate malate; controls received placebo pills.
Bone mineral density and bone mineral content of the lumbar spine and total body were measured by dual-energy x-ray absorptiometry and calcium excretion from 24-hour urine specimens.
Calcium intake from dietary sources averaged 960 mg/d for the entire study group. The supplemented group received, on average, an additional 354 mg/d of calcium. The supplemented group compared with the placebo group had greater increases of lumbar spine bone density (18.7% vs 15.8%; P = .03), lumbar spine bone mineral content (39.4% vs 34.7%; P = .06), total body bone mineral density (9.6% vs 8.3%; P = .05), and 24-hour urinary calcium excretion (90.4 vs 72.9 mg/d; P = .02), respectively.
Increasing daily calcium intake from 80% of the recommended daily allowance to 110% via supplementation with calcium citrate malate resulted in significant increases in total body and spinal bone density in adolescent girls. The increase of 24 g of bone gain per year among the supplemented group translates to an additional 1.3% skeletal mass per year during adolescent growth, which may provide protection against future osteoporotic fracture.
This study examined the effect of the sodium content of drinks on the rehydration process after exercise. Six healthy male volunteers were dehydrated by a mean (SEM) of 1.9(0.0) % of body mass by intermittent cycle exercise in a warm (32 degrees C), humid (54% RH) environment. Subjects exercised on four occasions at weekly intervals with each trial beginning in the morning, 3 h after a standard breakfast. Over a 30-min period beginning 30 min after the end of exercise, subjects ingested one of the four test drinks in a volume equivalent to 1.5 times their body mass loss. Drink composition was constant except for the sodium (and matching anion) content. Sodium content of drinks A, B, C and D was 2, 26, 52 and 100 mmol.l-1, respectively. Treatment order was randomised using a four-way crossover incomplete block design. Blood and urine samples were obtained before exercise, immediately before and after the rehydration period and at 0.5, 1.5, 3.5 and 5.5 h after the end of the rehydration period. Data were analysed by parametric or non-parametric statistical tests are appropriate. The volume of fluid consumed was the same on all trials [2045(45) ml]. From the 1.5-h sample onwards, a significant treatment effect on cumulative urine output was apparent, with the volume excreted being inversely related to the sodium content of the drink consumed. By the end of the trial, subjects were in net negative fluid balance on trials A [by 689(124) ml] and B [by 359(87) ml]; on trials C [-2(79) ml] and D [+98(67) ml], subjects were approximately euhydrated. Cumulative urinary sodium output was higher on treatment D than on the other trials after 5.5 h. Plasma volume was lower after exercise than before; on trials B, C and D, plasma volume was higher than the pre-exercise value from 0.5 h after the end of the rehydration period onwards. On trial A, plasma volume was higher than the pre-exercise value at 3.5 and 5.5 h after the end of the rehydration period. At 1.5 h after the end of the rehydration period, the increase in plasma volume was greater on trials C and D than on trial A. These results suggest that the fraction of the ingested fluid that was retained was directly related to the sodium concentration.