RESUMO
A comprehensive recent study by Trommelen et al. demonstrated that muscle tissue exhibits a greater capacity to incorporate exogenous exogenous protein-derived amino acids into bound muscle protein than was previously appreciated, at least when measured in "anabolically sensitive," recreationally active (but not resistance-trained), young men following resistance exercise. Moreover, this study demonstrated that the duration of the postprandial period is modulated by the dose of ingested protein contained within a meal, that is, the postexercise muscle protein synthesis response to protein ingestion was more prolonged in 100PRO than 25PRO. Both observations represent important scientific advances in the field of protein metabolism. However, we respectfully caution that the practical implications of these findings may have been misinterpreted, at least in terms of dismissing the concept of protein meal distribution as an important factor in optimizing muscle tissue anabolism and/or metabolic health. Moreover, based on emerging evidence, this idea that the anabolic response to protein ingestion has no upper limit does not appear to translate to resistance-trained young women.
Assuntos
Proteínas Alimentares , Exercício Físico , Proteínas Musculares , Músculo Esquelético , Período Pós-Prandial , Treinamento Resistido , Humanos , Proteínas Alimentares/administração & dosagem , Músculo Esquelético/metabolismo , Proteínas Musculares/metabolismo , Exercício Físico/fisiologia , Masculino , Feminino , Aminoácidos/administração & dosagem , Aminoácidos/metabolismo , Fenômenos Fisiológicos da Nutrição Esportiva , Recuperação após o ExercícioRESUMO
Compared with adult athletes, rather little is known about supplementation behavior in adolescent athletes. This study's aim was to determine elite adolescent athletes' supplement use and sources of information relating thereto. A total of 430 (87%) of 496 questioned athletes returned the anonymized questionnaire. Thereof, 84% consumed at least one weekly supplement and 97% indicated some supplement intake during the previous 4 weeks. On average, 13.3 supplement servings were consumed per week. The 25th, 50th, and 75th percentile was 4.5, 10.5, and 20.0 servings per week, with a maximum of 67. The most prevalent supplements in use were multimineral products (41% of all athletes), multivitamins (34%), Vitamin C (34%), and Vitamin D (33%). Male athletes consumed significantly more Vitamin C and D, sports drinks, protein powder, and recovery products compared with female athletes; whereas, women consumed more iron supplements. The three most important motives for supplement use were recovery support (40%), health maintenance (39%), and performance enhancement (30%). The most frequent answers to the question "who recommended that you use supplements" were family/friends (36%), a physician (27%), and a trainer/coach (25%). The main three information sources about the supplements in use were the persons who recommended the supplementation (56%), the internet (25%), and information provided by supplement suppliers (11%). A positive doping attitude was associated with the consumption of performance enhancing supplements (p = .017). In conclusion, this study among elite adolescent Swiss athletes indicates a widespread and large-scale use of dietary supplements, which was associated with a low level of information quality.
Assuntos
Atletas , Esportes , Adolescente , Adulto , Suplementos Nutricionais , Feminino , Humanos , Masculino , Inquéritos e Questionários , Suíça , VitaminasRESUMO
The aim of this study was to investigate whether caffeine and/or sodium citrate have an ergogenic effect on the 1,500-m exercise performance in elite wheelchair athletes. A placebo-controlled, randomized, cross-over and double-blind study design was conducted with the four treatments placebo, caffeine, sodium citrate and the combination of caffeine and sodium citrate. Nine healthy, elite wheelchair-racing athletes (median: [min; max] age: 28 y [23; 54]; height: 173 cm [165; 188]; weight: 62.9 kg [48.9; 68.4], category T53/54) completed the study. All athletes were national team members, including several Paralympic Games, World and European Championship medalists. The athletes performed a 1,500-m time trial four times on a wheelchair training roller. Time to complete 1,500-m, pH, bicarbonate and sodium concentration as well as lactate concentration were measured. The time to complete 1,500-m was not significantly different between the four treatments (placebo: 170.6 s [141.7; 232.0]; caffeine: 179.5 s [134.8; 239.6]; sodium citrate: 178.3 s [136.4; 247.1]; combination: 177.6 s [136.1; 256.2]). However, pH and bicarbonate concentrations were significantly increased with sodium citrate ingestion compared with placebo. Moreover, maximal lactate concentrations were significantly higher in the caffeine and the combination treatment compared with placebo. The supplementation with sodium citrate and/or caffeine did not provide an ergogenic effect on the 1,500-m exercise performance in wheelchair elite athletes.
Assuntos
Desempenho Atlético/fisiologia , Cafeína/farmacologia , Citratos/farmacologia , Pessoas com Deficiência , Esforço Físico/efeitos dos fármacos , Esportes , Cadeiras de Rodas , Adulto , Atletas , Bicarbonatos/sangue , Estimulantes do Sistema Nervoso Central/farmacologia , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Concentração de Íons de Hidrogênio , Ácido Láctico/sangue , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Citrato de Sódio , Adulto JovemRESUMO
There is a consensus claiming an ergogenic effect of carbohydrates ingested in the proximity of or during a performance bout. However, in performance studies, the protocols that are used are often highly standardized (e.g. fasted subjects, constant exercise intensity with time-to-exhaustion tests), and do not necessarily reflect competitive real-life situations. Therefore, we aimed at systematically summarizing all studies with a setting mimicking the situation of a real-life competition (e.g., subjects exercising in the postprandial state and with time-trial-like performance tests such as fixed distance or fixed time tests). We performed a PubMed search by using a selection of search terms covering inclusion criteria for sport, athletes, carbohydrates, and fluids, and exclusion criteria for diseases and animals. This search yielded 16,658 articles and the abstract of 16,508 articles contained sufficient information to identify the study as non-eligible for this review. The screening of the full text of the remaining 150 articles yielded 17 articles that were included in this review. These articles described 22 carbohydrate interventions covering test durations from 26 to 241 min (mostly cycling). We observed no performance improvement with half of the carbohydrate interventions, while the other half of the interventions had significant improvement between 1% and 13% (improvement with one of five interventions lasting up to 68 min and with 10 of 17 interventions lasting between 70 and 241 min). Thus, when considering only studies with a setting mimicking real-life competition, there is a mixed general picture about the ergogenic effect of carbohydrates ingested in the proximity of or during a performance bout with an unlikely effect with bouts up to perhaps 70 min and a possible but not compelling ergogenic effect with performance durations longer than about 70 min.
Assuntos
Desempenho Atlético/fisiologia , Carboidratos da Dieta/administração & dosagem , Suplementos Nutricionais , Exercício Físico/fisiologia , Atletas , Humanos , Metanálise como Assunto , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
The previously separate dietary protein recommendations for strength and endurance athletes are no longer supported, and the daily intake for adult athletes suggested by most of the entities is about 1.5 g · kg(-1) body mass with a range of perhaps 1.0 to 2.0 g · kg(-1) body mass. This recommendation is a broad landmark that needs to be adapted to the individual circumstances of the athlete. Research of the past decade indicates a beneficial effect with respect to a positive net muscular protein balance if athletes ingest some protein before an exercise bout. The amount of protein to be ingested to elicit the highest benefit is about 10 to 20 g · h(-1), but due to the insufficient amount of available data, it is not possible yet to rank different protein types or sources according to their anabolic potential. A simple way to translate the nutrient-based recommendations is the Swiss Food Pyramid for Athletes, which ensures a sufficient intake of energy, and all macro- and micronutrients in relation to the volume and intensity of the daily exercise.
Assuntos
Atletas , Proteínas Alimentares/metabolismo , Promoção da Saúde , Adulto , Aminoácidos/administração & dosagem , Aminoácidos/metabolismo , Composição Corporal , Proteínas Alimentares/administração & dosagem , Suplementos Nutricionais , Exercício Físico , Comportamento Alimentar , Humanos , Política Nutricional , Necessidades Nutricionais , Esportes , SuíçaRESUMO
The purpose of this study was to examine the effects of three-week consumption of green tea extract (GTE) supplementation on time trial performance and metabolism during cycling in endurance athletes. Nine endurance-trained men participated in this double-blind and placebo-controlled cross-over study. At the end of the supplementation period with GTE (159 mg/day total catechins) or placebo, respectively, subjects cycled at 50 % of the individual maximal power output for 2 hours, followed by a 30-minute time trial. Respiratory gas exchange, fatty acids, 3-beta-hydroxybutyrate, lactate, glucose, interleukin-6, thiobarbituric acid reactive substances, creatine kinase, and C-reactive protein (CRP) were measured 1 hour before, during, and 1 hour after the exercise test. Blood lipids were measured at rest before cycling. There was no significant effect on performance, energy metabolism, or any other measured parameter, except for CRP, which was significantly reduced (p = 0.045) after GTE supplementation compared to placebo. GTE supplementation did not affect time trial performance and energy metabolism in endurance-trained men in the non-fasting state. Further studies with athletes, particularly in the fed state, but with higher GTE doses, are needed to address the question whether green tea may influence energy metabolism and performance in athletes.
Assuntos
Desempenho Atlético/fisiologia , Suplementos Nutricionais , Metabolismo Energético , Resistência Física/fisiologia , Extratos Vegetais/administração & dosagem , Chá/química , Ciclismo , Proteína C-Reativa/análise , Estudos Cross-Over , Método Duplo-Cego , Teste de Esforço , Frequência Cardíaca , Humanos , Mediadores da Inflamação/sangue , Lipídeos/sangue , Masculino , Consumo de Oxigênio , Extratos Vegetais/química , Fatores de TempoRESUMO
BACKGROUND: The aim of this study was to screen the prevalence of supplement use in Swiss fitness center users and what information sources they consulted. METHODS: Customers of 10 fitness centers were screened with a quantitative questionnaire. RESULTS: Eighty two percent of the 417 fitness center users consumed at least one supplement per week. Supplement intake correlated with training frequency (rs = 0.253, p < 0.001). The most prevalent products were protein supplements (used by 49% of the study population), magnesium (34%), and multi-micronutrient supplements (31%). The average number of supplement servings per week among consumers was 17.1 (SD: 16.1, median: 11.0) and the average number of different products used was 6.9 (SD: 4.4, median: 6.0). The most frequently used information sources were the coach/trainer (28%), the website of the supplement seller (26%), and training peers (24%). Thirty seven percent were informed or informed themselves about potential risks associated with the supplement used. The leading reasons for selecting the information source were the desire for scientific-based information followed by the education level of the informing person. CONCLUSIONS: A high prevalence of supplement intake among Swiss fitness center users was associated with a low level of information quality and a low prevalence of risk information. A discrepancy between a desire for high quality evidence-based information and a contrasting behavior was detected.
Assuntos
Comportamento do Consumidor/estatística & dados numéricos , Suplementos Nutricionais/estatística & dados numéricos , Academias de Ginástica , Conhecimentos, Atitudes e Prática em Saúde , Comportamentos de Risco à Saúde , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Necessidades Nutricionais , Prevalência , Inquéritos e Questionários , Suíça , Adulto JovemRESUMO
The consumption of green tea has been generally associated with beneficial effects on human whole-body metabolism and recent investigations with animals indicate favorable effects of green tea extracts (GTE) on energy metabolism during exercise and aerobic exercise performance. Therefore, the purpose of this study was to examine the effects of a three-week supplementation with GTE on human energy metabolism during submaximal cycling exercise. In a randomized, double-blind crossover setting, ten healthy endurance-trained men exercised for 2 hours at 50 % W(max) before and after three weeks of placebo or GTE supplementation (GTE containing about 160 mg x day(-1) total catechins, of which about 70 mg x day(-1) was epigallocatechin-3-gallate). The GTE supplementation did not influence indices of fat and energy metabolism (fatty acids, 3-beta-hydroxybutyrate, triacylglycerol, low-density-lipoprotein cholesterol, total cholesterol, lactate, glucose, oxygen uptake, respiratory exchange ratio, energy expenditure), inflammation processes (interleukin-6, C-reactive protein), and oxidative stress (thiobarbituric-acid reactive substances, oxidized low-density-lipoprotein cholesterol), but plasma creatine kinase concentration at rest and during exercise was significantly lower (p = 0.039) and high-density-lipoprotein cholesterol concentration at rest was significantly higher (p = 0.043) compared to placebo. In conclusion, these results suggest only slight effects on whole-body metabolism after supplementation with GTE.
Assuntos
Camellia sinensis/química , Catequina/análogos & derivados , Metabolismo Energético , Metabolismo dos Lipídeos , Resistência Física/fisiologia , Esforço Físico/fisiologia , Extratos Vegetais/administração & dosagem , Adiposidade , Adulto , Análise de Variância , Ciclismo , Biomarcadores/análise , Catequina/administração & dosagem , Catequina/análise , HDL-Colesterol/sangue , Creatina Quinase/sangue , Estudos Cross-Over , Suplementos Nutricionais , Método Duplo-Cego , Teste de Esforço , Humanos , Inflamação/metabolismo , Masculino , Estresse Oxidativo , Extratos Vegetais/química , Adulto JovemRESUMO
Background: A detrimental consequence of diet-induced weight loss, common in athletes who participate in weight cutting sports, is muscle loss. Dietary omega-3 polyunsaturated fatty acids (n-3PUFA) exhibit a protective effect on the loss of muscle tissue during catabolic situations such as injury-simulated leg immobilization. This study aimed to investigate the influence of dietary n-3PUFA supplementation on changes in body composition and muscle strength following short-term diet-induced weight loss in resistance-trained men. Methods: Twenty resistance-trained young (23 ± 1 years) men were randomly assigned to a fish oil group that supplemented their diet with 4 g n-3PUFA, 18 g carbohydrate, and 5 g protein (FO) or placebo group containing an equivalent carbohydrate and protein content (CON) over a 6 week period. During weeks 1-3, participants continued their habitual diet. During week 4, participants received all food items to control energy balance and a macronutrient composition of 50% carbohydrate, 35% fat, and 15% protein. During weeks 5 and 6, participants were fed an energy-restricted diet equivalent to 60% habitual energy intake. Body composition and strength were measured during weeks 1, 4, and 6. Results: The decline in total body mass (FO = -3.0 ± 0.3 kg, CON = -2.6 ± 0.3 kg), fat free mass (FO = -1.4 ± 0.3 kg, CON = -1.2 ± 0.3 kg) and fat mass (FO = -1.4 ± 0.2 kg, CON = -1.3 ± 0.3 kg) following energy restriction was similar between groups (all p > 0.05; d: 0.16-0.39). Non-dominant leg extension 1 RM increased (6.1 ± 3.4%) following energy restriction in FO (p < 0.05, d = 0.29), with no changes observed in CON (p > 0.05, d = 0.05). Dominant leg extension 1 RM tended to increase following energy restriction in FO (p = 0.09, d = 0.29), with no changes in CON (p > 0.05, d = 0.06). Changes in leg press 1 RM, maximum voluntary contraction and muscular endurance following energy restriction were similar between groups (p > 0.05, d = 0.05). Conclusion: Any possible improvements in muscle strength during short-term weight loss with n-3PUFA supplementation are not related to the modulation of FFM in resistance-trained men.
RESUMO
OBJECTIVE: This study investigated the influence of regular endurance training on the glycemic index (GI) of a breakfast cereal in women as previous results from men indicate that endurance training may influence the GI. METHODS: Subjects were 17 sedentary (SE) and 19 endurance trained (ET) healthy, young, adult women of normal body mass index. All subjects performed two tests with the reference food glucose and two tests with a breakfast cereal in a randomized order. Capillary and venous whole blood glucose as well as venous plasma insulin was measured. RESULTS: The GI did not differ between SE and ET, irrespective of its calculation from the capillary (mean +/- standard error: 61.4 +/- 4.3 and 69.5 +/- 4.7 for SE and ET respectively, p = 0.21) or the venous blood glucose (60.8 +/- 8.1 and 64.4 +/- 6.2, p = 0.72). The insulinemic index did not differ between the SE and ET subjects (p = 0.75). CONCLUSION: The results come along with many other data, indicating that the GI seems to be independent of subject-specific factors, but are in contrast to previous results obtained with men where we found a GI dependence on the training state.
Assuntos
Índice Glicêmico/fisiologia , Resistência Física/fisiologia , Adulto , Área Sob a Curva , Glicemia/análise , Glicemia/fisiologia , Estudos Cross-Over , Feminino , Humanos , Insulina/sangue , Insulina/fisiologiaRESUMO
OBJECTIVE: Hyperhydration and exercise-associated hyponatremia (EAH) are critical issues during endurance events. We studied a cohort of marathon runners to examine EAH's prevalence in a marathon with a short time limit and to investigate underlying mechanisms that may be responsible for its development. DESIGN: Observational cohort study. SETTING: 2006 Zurich Marathon (cool and rainy weather, time limit of 5 hours). PARTICIPANTS: 167 marathon runners were recruited the month before the race. MAIN OUTCOME MEASURES: Body mass, plasma sodium, and osmolality were measured just before the start and immediately after the race. Fluid intake during the race was ascertained by a recall questionnaire. RESULTS: Five subjects (3 %) developed asymptomatic EAH, and no symptomatic EAH was found. Body mass change during the race correlated similarly with postrace sodium levels (r = -0.72, P < 0.0001) and with sodium change during the race (r = -0.66, P < 0.0001). Postrace sodium levels correlated significantly with sodium change during the race (r = 0.74, P < 0.0001). Fluid intake correlated significantly (r = -0.43, P < 0.0001) with plasma sodium change between the start and finish of the race. Postrace sodium levels and postrace osmolality were significantly correlated (r = 0.68, P < 0.0001). CONCLUSION: In this study we observed a relatively low incidence of EAH in subjects running the marathon in around 2.5 to 5 hours and in a cool environment. Plasma sodium change during the race and postrace sodium levels correlated with body mass change. There was also a direct correlation between fluid intake and plasma sodium change during the race.
Assuntos
Hiponatremia/fisiopatologia , Corrida/fisiologia , Equilíbrio Hidroeletrolítico/fisiologia , Adulto , Estudos de Coortes , Ingestão de Líquidos , Feminino , Humanos , Hiponatremia/diagnóstico , Hiponatremia/epidemiologia , Incidência , Masculino , Pessoa de Meia-Idade , Suíça/epidemiologiaRESUMO
Background: Iron status is a determinant of physical performance, but training may induce both low-grade inflammation and erythropoiesis, exerting opposing influences on hepcidin and iron metabolism. To our knowledge, the combined effects on iron absorption and utilization during training have not been examined directly in humans. Objective: We hypothesized that 3 wk of exercise training in recreational male runners would decrease oral iron bioavailability by increasing inflammation and hepcidin concentrations. Design: In a prospective intervention, nonanemic, iron-sufficient men (n = 10) completed a 34-d study consisting of a 16-d control phase and a 22-d exercise-training phase of 8 km running every second day. We measured oral iron absorption and erythroid iron utilization using oral 57Fe and intravenous 58Fe tracers administered before and during training. We measured hemoglobin mass (mHb) and total red blood cell volume (RCV) by carbon monoxide rebreathing. Iron status, interleukin-6 (IL-6), plasma hepcidin (PHep), erythropoietin (EPO), and erythroferrone were measured before, during, and after training. Results: Exercise training induced inflammation, as indicated by an increased mean ± SD IL-6 (0.87 ± 1.1 to 5.17 ± 2.2 pg/mL; P < 0.01), while also enhancing erythropoiesis, as indicated by an increase in mean EPO (0.66 ± 0.42 to 2.06 ± 1.6 IU/L), mHb (10.5 ± 1.6 to 10.8 ± 1.8 g/kg body weight), and mean RCV (30.7 ± 4.3 to 32.7 ± 4.6 mL/kg) (all P < 0.05). Training tended to increase geometric mean iron absorption by 24% (P = 0.083), consistent with a decreased mean ± SD PHep (7.25 ± 2.14 to 5.17 ± 2.24 nM; P < 0.05). The increase in mHb and erythroid iron utilization were associated with the decrease in PHep (P < 0.05). Compartmental modeling indicated that iron for the increase in mHb was obtained predominantly (>80%) from stores mobilization rather than from increased dietary absorption. Conclusions: In iron-sufficient men, mild intensification of exercise intensity increases both inflammation and erythropoiesis. The net effect is to decrease hepcidin concentrations and to tend to increase oral iron absorption. This trial was registered at clinicaltrials.gov as NCT01730521.
Assuntos
Eritropoese/fisiologia , Exercício Físico/fisiologia , Hepcidinas/sangue , Inflamação/epidemiologia , Ferro/metabolismo , Corrida/fisiologia , Adulto , Índices de Eritrócitos , Eritrócitos/metabolismo , Hemoglobinas/análise , Humanos , Interleucina-6/sangue , Ferro/sangue , Ferro/farmacocinética , Isótopos de Ferro/sangue , Isótopos de Ferro/farmacocinética , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio , Estudos ProspectivosRESUMO
The glycemic index (GI) represents the relative postprandial blood glucose response to the ingestion of a food containing carbohydrate. Although regular physical exercise may influence glucose metabolism, it is not yet known if chronically performed exercise also affects the GI. The objective of this study was, therefore, to determine the GI of common meals (three breakfast cereals: B, C, D) in healthy, nonsmoking young males 2 who were either endurance-trained (n = 12) or sedentary (n = 11). Glucose was used as the reference food. The GI value between the endurance-trained and sedentary subjects differed significantly (p < 0.01). Pair-wise comparisons between endurance-trained and sedentary subjects within the different test meals were significant for test meal D (p = 0.002), marginally non-significant for meal C (p = 0.052) and not significant for meal B (p = 0.204). These results suggest that the GI of some complex foods may depend on the training status of healthy young subjects.
Assuntos
Exercício Físico/fisiologia , Índice Glicêmico/fisiologia , Adulto , Glicemia/análise , Dieta , Grão Comestível , Jejum , Alimentos , Humanos , Masculino , Resistência Física/fisiologiaRESUMO
Dietary nitrate has been reported to lower oxygen consumption in moderate- and severe-intensity exercise. To date, it is unproven that sodium nitrate (NaNO3(-); NIT) and nitrate-rich beetroot juice (BR) have the same effects on oxygen consumption, blood pressure, and plasma nitrate and nitrite concentrations or not. The aim of this study was to compare the effects of different dosages of NIT and BR on oxygen consumption in male athletes. Twelve healthy, well-trained men (median [minimum; maximum]; peak oxygen consumption: 59.4 mL·min(-1)·kg(-1) [40.5; 67.0]) performed 7 trials on different days, ingesting different nitrate dosages and placebo (PLC). Dosages were 3, 6, and 12 mmol nitrate as concentrated BR or NIT dissolved in plain water. Plasma nitrate and nitrite concentrations were measured before, 3 h after ingestion, and postexercise. Participants cycled for 5 min at moderate intensity and further 8 min at severe intensity. End-exercise oxygen consumption at moderate intensity was not significantly different between the 7 trials (p = 0.08). At severe-intensity exercise, end-exercise oxygen consumption was ~4% lower in the 6-mmol BR trial compared with the 6-mmol NIT (p = 0.003) trial as well as compared with PLC (p = 0.010). Plasma nitrite and nitrate concentrations were significantly increased after the ingestion of BR and NIT with the highest concentrations in the 12-mmol trials. Plasma nitrite concentration between NIT and BR did not significantly differ in the 6-mmol (p = 0.27) and in the 12-mmol (p = 0.75) trials. In conclusion, BR might reduce oxygen consumption to a greater extent compared with NIT.
Assuntos
Beta vulgaris/química , Exercício Físico , Sucos de Frutas e Vegetais/análise , Nitratos/administração & dosagem , Consumo de Oxigênio/efeitos dos fármacos , Raízes de Plantas/química , Adulto , Atletas , Pressão Sanguínea/efeitos dos fármacos , Índice de Massa Corporal , Estudos Cross-Over , Suplementos Nutricionais , Relação Dose-Resposta a Droga , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Nitratos/sangue , Nitritos/sangue , Método Simples-Cego , Adulto JovemRESUMO
In this case study, we evaluated the effect of colocation on the drug development process using value-stream mapping (VSM) on the Novartis Campus in Basel, Switzerland. We compared a colocated team with a control group that was not colocated. The data showed that colocation was not associated with increased process speed in terms of lead lines. However, the colocated team communicated more and reported beneficial experiences, such as faster working processes or improved mutual understanding. VSM workshops revealed not only performance indicators about colocation, but also enhanced communication and cooperation through the evolving discussion.
Assuntos
Descoberta de Drogas/organização & administração , Indústria Farmacêutica/organização & administração , Eficiência Organizacional , Pesquisa Biomédica , Comunicação , Comportamento Cooperativo , Humanos , Local de TrabalhoRESUMO
PURPOSE: To examine the influence of dietary protein on lean body mass loss and performance during short-term hypoenergetic weight loss in athletes. METHODS: In a parallel design, 20 young healthy resistance-trained athletes were examined for energy expenditure for 1 wk and fed a mixed diet (15% protein, 100% energy) in the second week followed by a hypoenergetic diet (60% of the habitual energy intake), containing either 15% (approximately 1.0 g x kg(-1)) protein (control group, n = 10; CP) or 35% (approximately 2.3 g x kg(-1)) protein (high-protein group, n = 10; HP) for 2 wk. Subjects continued their habitual training throughout the study. Total, lean body, and fat mass, performance (squat jump, maximal isometric leg extension, one-repetition maximum (1RM) bench press, muscle endurance bench press, and 30-s Wingate test) and fasting blood samples (glucose, nonesterified fatty acids (NEFA), glycerol, urea, cortisol, free testosterone, free Insulin-like growth factor-1 (IGF-1), and growth hormone), and psychologic measures were examined at the end of each of the 4 wk. RESULTS: Total (-3.0 +/- 0.4 and -1.5 +/- 0.3 kg for the CP and HP, respectively, P = 0.036) and lean body mass loss (-1.6 +/- 0.3 and -0.3 +/- 0.3 kg, P = 0.006) were significantly larger in the CP compared with those in the HP. Fat loss, performance, and most blood parameters were not influenced by the diet. Urea was higher in HP, and NEFA and urea showed a group x time interaction. Fatigue ratings and "worse than normal" scores on the Daily Analysis of Life Demands for Athletes were higher in HP. CONCLUSIONS: These results indicate that approximately 2.3 g x kg(-1) or approximately 35% protein was significantly superior to approximately 1.0 g x kg(-1) or approximately 15% energy protein for maintenance of lean body mass in young healthy athletes during short-term hypoenergetic weight loss.
Assuntos
Índice de Massa Corporal , Proteínas Alimentares/administração & dosagem , Ingestão de Energia/fisiologia , Esportes , Redução de Peso/fisiologia , Adolescente , Adulto , Composição Corporal , Exercício Físico/fisiologia , Humanos , Masculino , Adulto JovemRESUMO
Cinnamon and vinegar or acetic acid were reported to reduce the postprandial blood glucose response. We hypothesized that the combination of these substances might result in an additive effect. Therefore, we determined the 2-hour postprandial blood glucose and satiety response to a milk rice meal supplemented with either cinnamon or acetic acid on their own or in combination. Subjects (n = 27) consumed the meal on 4 occasions as either pure (control trial), with 4 g cinnamon, 28 mmol acetic acid, or the combination of cinnamon + acetic acid. Blood glucose and satiety were assessed before eating and 15, 30, 45, 60, 90, and 120 minutes postprandially. At 15 minutes, the combination of cinnamon + acetic acid resulted in a significantly reduced blood glucose concentration compared with the control meal (P = .021). The incremental area under the blood glucose response curve over 120 minutes did, however, not differ between the trials (P = .539). The satiety score of the cinnamon + acetic acid trial was significantly higher than that in the control trial at 15 (P = .024) and 30 minutes (P = .024), but the incremental area under the curve of the satiety response did not differ (P = .116) between the trials. In conclusion, the significant effect of the combination of cinnamon and acetic acid on blood glucose and satiety immediately after meal intake indicated an additive effect of the 2 substances. Whether larger doses of cinnamon and acetic acid may result in a more substantial additive effect on blood glucose or satiety remains to be investigated.
Assuntos
Ácido Acético/farmacologia , Glicemia/metabolismo , Cinnamomum zeylanicum , Preparações de Plantas/farmacologia , Saciação/efeitos dos fármacos , Adulto , Animais , Área Sob a Curva , Sinergismo Farmacológico , Quimioterapia Combinada , Feminino , Humanos , Masculino , Leite , Oryza , Período Pós-Prandial , Adulto JovemRESUMO
Food-guide pyramids help translate nutrient goals into a visual representation of suggested food intake on a population level. No such guidance system has ever been specifically designed for athletes. Therefore, the authors developed a Food Pyramid for Swiss Athletes that illustrates the number of servings per food group needed in relation to the training volume of an athlete. As a first step, an average energy expenditure of 0.1 kcal . kg(-1) . min(-1) for exercise was defined, which then was translated into servings of different food groups per hour of exercise per day. Variable serving sizes were defined for athletes' different body-mass categories. The pyramid was validated by designing 168 daily meal plans according to the recommendations of the pyramid for male and female athletes of different body-mass categories and training volumes of up to 4 hr/d. The energy intake of the meal plans met the calculated reference energy requirement by 97% +/- 9%. The carbohydrate and protein intakes were linearly graded from 4.6 +/- 0.6-8.5 +/- 0.8 g . kg(-1) . d(-1) and 1.6 +/- 0.2-1.9 +/- 0.2 g . kg(-1) . d(-1), respectively, for training volumes of 1-4 hr of exercise per day. The average micronutrient intake depended particularly on the dietary energy intake level but was well above the dietary reference intake values for most micronutrients. No tolerable upper intake level was exceeded for any micronutrient. Therefore, this Food Pyramid for Swiss Athletes may be used as a new tool in sports nutrition education (e.g., teaching and counseling).