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1.
J Sci Med Sport ; 23(1): 41-47, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31466868

RESUMO

OBJECTIVES: To conduct a systematic review and a meta-analysis of studies exploring the effects of caffeine and/or sodium bicarbonate on performance in the Yo-Yo test. DESIGN: Systematic review and meta-analysis. METHODS: A total of six databases were searched, and random-effects meta-analyses were performed examining the isolated effects of caffeine and sodium bicarbonate on performance in the Yo-Yo test. RESULTS: After reviewing 988 search records, 15 studies were included. For the effects of caffeine on performance in the Yo-Yo test, the meta-analysis indicated a significant favoring of caffeine as compared with the placebo conditions (p=0.022; standardized mean difference [SMD]=0.17; 95% CI: 0.08, 0.32; +7.5%). Subgroup analyses indicated that the effects of caffeine were significant for the level 2 version of the Yo-Yo test, but not level 1. Four out of the five studies that explored the effects of sodium bicarbonate used the level 2 version of the Yo-Yo test. The pooled SMD favored the sodium bicarbonate condition as compared with the placebo/control conditions (p=0.007; SMD: 0.36; 95% CI: 0.10, 0.63; +16.0%). CONCLUSIONS: This review demonstrates that isolated ingestion of caffeine and sodium bicarbonate enhances performance in the Yo-Yo test. Given these ergogenic effects, the intake of caffeine and sodium bicarbonate before the Yo-Yo test needs to be standardized (i.e., either restricted or used in the same way before each testing session). Furthermore, the results suggest that individuals competing in sports involving intermittent exercise may consider supplementing with caffeine or sodium bicarbonate for acute improvements in performance.


Assuntos
Cafeína/administração & dosagem , Substâncias para Melhoria do Desempenho/administração & dosagem , Bicarbonato de Sódio/administração & dosagem , Desempenho Atlético , Exercício , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto
2.
Braz J Med Biol Res ; 52(12): e9169, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31826183

RESUMO

We investigated the effect of caffeine ingestion combined with a 2-wk sprint interval training (SIT) on training-induced reductions in body adiposity. Twenty physically-active men ingested either 5 mg/kg of cellulose as a placebo (PLA, n=10) or 5 mg/kg of caffeine (CAF, n=10) 60 min before each SIT session (13×30 s sprint/15 s of rest). Body mass and skinfold thickness were measured pre- and post-training. Energy expenditure was measured at rest, during exercise, and 45 min after exercise in the first SIT session. Body fat was similar between PLA and CAF groups at pre-training (P>0.05). However, there was a significant decrease in body fat after training in the CAF group (-5.9±4.2%, P<0.05) but not in PLA (1.5±8.0%, P>0.05). There was no difference in energy expenditure at rest and during exercise between PLA and CAF groups (P>0.05), but the post-exercise energy expenditure was 18.3±21.4% greater in the CAF than in the PLA group (P<0.05). In conclusion, caffeine ingestion before SIT sessions induced a body fat loss that may be associated with higher post-exercise energy expenditure.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Cafeína/administração & dosagem , Metabolismo Energético/efeitos dos fármacos , Treinamento Intervalado de Alta Intensidade , Consumo de Oxigênio/efeitos dos fármacos , Adulto , Método Duplo-Cego , Humanos , Masculino , Adulto Jovem
3.
PLoS One ; 14(12): e0226220, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31881028

RESUMO

STUDY OBJECTIVES: Normal timing and duration of sleep is vital for all physical and mental health. However, many sleep-related studies depend on self-reported sleep measurements, which have limitations. This study aims to investigate the association of physical activity and sociodemographic characteristics including age, gender, coffee intake and social status with objective sleep measurements. METHODS: A cross-sectional analysis was carried out on 82995 participants within the UK Biobank cohort. Sociodemographic and lifestyle information were collected through touch-screen questionnaires in 2007-2010. Sleep and physical activity parameters were later measured objectively using wrist-worn accelerometers in 2013-2015 (participants were aged 43-79 years and wore watches for 7 days). Participants were divided into 5 groups based on their objective sleep duration per night (<5 hours, 5-6 hours, 6-7 hours, 7-8 hours and >8 hours). Binary logistic models were adjusted for age, gender and Townsend Deprivation Index. RESULTS: Participants who slept 6-7 hours/night were the most frequent (33.5%). Females had longer objective sleep duration than males. Short objective sleep duration (<6 hours) correlated with older age, social deprivation and high coffee intake. Finally, those who slept 6-7 hours/night were most physically active. CONCLUSIONS: Objectively determined short sleep duration was associated with male gender, older age, low social status and high coffee intake. An inverse 'U-shaped' relationship between sleep duration and physical activity was also established. Optimal sleep duration for health in those over 60 may therefore be shorter than younger groups.


Assuntos
Acelerometria/instrumentação , Cafeína/administração & dosagem , Exercício/fisiologia , Sono/fisiologia , Adulto , Idoso , Estudos Transversais , Feminino , Monitores de Aptidão Física , Humanos , Estilo de Vida , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Autorrelato , Reino Unido
4.
J Sports Med Phys Fitness ; 59(9): 1435-1441, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31610637

RESUMO

BACKGROUND: This study investigated the effects of coffee ingestion with supplemental caffeine (CAF) on serum testosterone (T) responses to exercise in recreationally strength-trained males. METHODS: Subjects ingested 6 mg/kg body weight of caffeine via 12 ounces of coffee (CAF) supplemented with anhydrous caffeine or decaffeinated (DEC) coffee prior to exercise in a randomized, within-subject, crossover design. The exercise session consisted of 21 minutes of high-intensity interval cycling (alternating intensities at power outputs associated with 2.0 mmol/L lactate for two minutes and 4.0 mmol/L lactate for one minute) followed by resistance exercise (seven exercises, three sets of ten repetitions, 65% 1RM, one-minute rest periods). Subjects also completed repetitions to fatigue tests and soreness scales to determine muscle recovery 24 hours following the exercise. RESULTS: T was elevated immediately and 30-minutes post-exercise by 20.5% and 14.3% respectively (P<0.05). There was no main effect for treatment and no exercise x treatment interaction. There were no differences in repetitions to fatigue or soreness between treatments (P>0.05). No relationships were observed between T and any proxy of recovery. CONCLUSIONS: While past literature suggests caffeine may enhance T post-exercise, data from the current study suggest that augmented T response is not evident following anhydrous caffeine added to coffee. The duration of T elevation indicates that this protocol is beneficial to creating long-lasting increases in serum testosterone.


Assuntos
Cafeína/metabolismo , Treinamento Intervalado de Alta Intensidade/métodos , Treinamento de Resistência/métodos , Testosterona/sangue , Adulto , Cafeína/administração & dosagem , Café , Estudos Cross-Over , Humanos , Ácido Láctico/sangue , Masculino , Adulto Jovem
5.
J Int Soc Sports Nutr ; 16(1): 37, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31477133

RESUMO

The timing of macronutrient ingestion in relation to exercise is a purported strategy to augment muscle accretion, muscle and athletic performance, and recovery. To date, the majority of macronutrient nutrient timing research has focused on carbohydrate and protein intake. However, emerging research suggests that the strategic ingestion of various ergogenic aids and micronutrients may also have beneficial effects. Therefore, the purpose of this narrative review is to critically evaluate and summarize the available literature examining the timing of ergogenic aids (caffeine, creatine, nitrates, sodium bicarbonate, beta-alanine) and micronutrients (iron, calcium) on muscle adaptations and exercise performance. In summary, preliminary data is available to indicate the timing of caffeine, nitrates, and creatine monohydrate may impact outcomes such as exercise performance, strength gains and other exercise training adaptations. Furthermore, data is available to suggest that timing the administration of beta-alanine and sodium bicarbonate may help to minimize known untoward adverse events while maintaining potential ergogenic outcomes. Finally, limited data indicates that timed ingestion of calcium and iron may help with the uptake and metabolism of these nutrients. While encouraging, much more research is needed to better understand how timed administration of these nutrients and others may impact performance, health, or other exercise training outcomes.


Assuntos
Desempenho Atlético/fisiologia , Exercício , Micronutrientes/administração & dosagem , Substâncias para Melhoria do Desempenho/administração & dosagem , Fenômenos Fisiológicos da Nutrição Esportiva , Cafeína/administração & dosagem , Cálcio na Dieta/administração & dosagem , Creatina/administração & dosagem , Humanos , Ferro/administração & dosagem , Nitratos/administração & dosagem , Bicarbonato de Sódio/administração & dosagem , Fatores de Tempo , beta-Alanina/administração & dosagem
7.
Nutrients ; 11(9)2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31492050

RESUMO

BACKGROUND: this study examined the effects of caffeine supplementation on anaerobic performance, neuromuscular efficiency and upper and lower extremities fatigue in Olympic-level boxers. METHODS: Eight male athletes, members of the Spanish National Olympic Team, were enrolled in the study. In a randomized double-blind, placebo-controlled, counterbalanced, crossover design, the athletes completed 2 test sessions after the intake of caffeine (6 mg·kg-1) or placebo. Sessions involved initial measures of lactate, handgrip and countermovement jump (CMJ) performance, followed by a 30-seconds Wingate test, and then final measures of the previous variables. During the sessions, electromiography (EMG) data were recorded on the gluteus maximus, biceps femoris, vastus lateralis, gastrocnemius lateral head and tibialis anterior. RESULTS: caffeine enhanced peak power (6.27%, p < 0.01; Effect Size (ES) = 1.26), mean power (5.21%; p < 0.01; ES = 1.29) and reduced the time needed to reach peak power (-9.91%, p < 0.01; ES = 0.58) in the Wingate test, improved jump height in the CMJ (+2.4 cm, p < 0.01), and improved neuromuscular efficiency at peak power in the vastus lateralis (ES = 1.01) and gluteus maximus (ES = 0.89), and mean power in the vastus lateralis (ES = 0.95) and tibialis anterior (ES = 0.83). CONCLUSIONS: in these Olympic-level boxers, caffeine supplementation improved anaerobic performance without affecting EMG activity and fatigue levels in the lower limbs. Further benefits observed were enhanced neuromuscular efficiency in some muscles and improved reaction speed.


Assuntos
Boxe , Cafeína/administração & dosagem , Suplementos Nutricionais , Contração Muscular/efeitos dos fármacos , Fadiga Muscular/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Substâncias para Melhoria do Desempenho/administração & dosagem , Resistência Física/efeitos dos fármacos , Estudos Cross-Over , Método Duplo-Cego , Humanos , Masculino , Músculo Esquelético/fisiologia , Fatores de Tempo , Adulto Jovem
8.
J Int Soc Sports Nutr ; 16(1): 38, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31488190

RESUMO

BACKGROUND: Caffeine (CAF) supplementation could have a positive impact on physical performance and sport abilities. Nevertheless, the CAF-induced, dose-dependent influence on discipline-specific performance and combat activity in combat sports have not been sufficiently investigated. The aim of this study was to examine the effect of single ingestion of 3, 6, or 9 mg/kg body weight of CAF and placebo (PLA) on judo-specific performance and sparring combat activities. METHODS: In a randomised double-blind placebo-controlled cross-over design, acute pre-exercise supplementation with CAF (3, 6, or 9 mg/kg body weight) and placebo PLA in 22 male highly-trained judoists was examined. The study protocol involved five separate testing sessions using the Special Judo Fitness Test (SJFT) with heart rate monitoring, three judo sparring combats and evaluation of the rate of perceived exertion (RPE) using the Borg scale. RESULTS: Six and 9 mg/kg CAF improved SJFT performance, while 9 mg/kg increased combat activity. Three mg/kg CAF lacked any apparent positive ergogenic effect. Among athletes, who include CAF-containing products in their habitual diet (consumers), only 9 mg/kg CAF effectively enhanced SJFT performance, while in those who do not consume CAF-containing products at regular basis (non-consumers), the enhancing effect was achieved even at 6 mg/kg. CONCLUSIONS: Regarding combat sports, higher (6-9 mg/kg) than currently recommended CAF dosages (3-6 mg/kg) are apparently more effective in terms of judo-specific performance. However, the ergogenic CAF effect is not only dose-dependent, but it is also related to customary CAF consumption. TRIAL REGISTRATION: Clinical Trials Gov, NCT03822663 . Registered 28 January 2019 - Retrospectively registered.


Assuntos
Desempenho Atlético/fisiologia , Cafeína/farmacologia , Artes Marciais/fisiologia , Substâncias para Melhoria do Desempenho/farmacologia , Adolescente , Adulto , Cafeína/administração & dosagem , Estudos Cross-Over , Relação Dose-Resposta a Droga , Método Duplo-Cego , Teste de Esforço , Humanos , Masculino , Substâncias para Melhoria do Desempenho/administração & dosagem , Adulto Jovem
9.
Anticancer Res ; 39(9): 4653-4657, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31519563

RESUMO

BACKGROUND/AIM: Osteosarcoma is a recalcitrant neoplasm which occurs predominantly in adolescents and young adults. Recently, using a patient-derived orthotopic xenograft (PDOX) model of malignant soft-tissue sarcoma (STS), we showed that oral recombinant methioninase (o-rMETase), in combination with caffeine, was more efficacious than o-rMETase alone in inhibiting STS tumor growth. In the present report, we determined the efficacy of o-rMETase combined with oral caffeine on a cisplatinum (CDDP)-resistant osteosarcoma PDOX model. MATERIALS AND METHODS: Osteosarcoma PDOX models were randomly divided into seven treatment groups (6 mice in each group): untreated control; CDDP alone; o-rMETase alone; o-rMETase with caffeine; CDDP plus o-rMETase; CDDP plus caffeine; and CDDP plus o-rMETase with caffeine. Tumor size and body weight were measured throughout the treatment. RESULTS: Tumors regressed after treatment with CDDP plus o-rMETase with caffeine. Tumors treated with CDDP plus o-rMETase with caffeine also had the most necrosis. CONCLUSION: The combination of o-rMETase and caffeine together with first-line chemotherapy was efficacious for drug-resistant osteosarcoma and has clinical potential in the treatment of this highly-resistant neoplasm.


Assuntos
Antimetabólitos Antineoplásicos/administração & dosagem , Cafeína/administração & dosagem , Liases de Carbono-Enxofre/administração & dosagem , Cisplatino/administração & dosagem , Resistencia a Medicamentos Antineoplásicos , Administração Oral , Animais , Modelos Animais de Doenças , Humanos , Camundongos , Osteossarcoma/diagnóstico por imagem , Osteossarcoma/tratamento farmacológico , Osteossarcoma/patologia , Carga Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
10.
Med Hypotheses ; 131: 109301, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31443771

RESUMO

Caffeine is a well-established ergogenic aid, with its performance-enhancing effects replicated across a variety of exercise types. Caffeine exerts its performance-benefits through many mechanisms, including acting as an adenosine receptor antagonist, and serving to reduce sensations of fatigue and pain. One potential mechanism that is currently underexplored is whether caffeine's bitter taste mediates some of its ergogenic effects, which is discussed in this article. Previous research has demonstrated that bitter tastants have the ability to enhance performance, and this effect is mediated by bitter taste receptors in the mouth and gastrointestinal tract. Additionally, the ability to detect bitter tastes is subject to individual variation, raising the potential that the demonstrated inter-individual response to a standardised caffeine dose is potentially driven by differences in taste response. Finally, it appears that some of caffeine's performance-enhancing effects are driven by expectancy. As bitter taste may serve as a signal that caffeine has been ingested, it is possible that some of the expectancy effects of caffeine ingestion are driven by its bitter taste. These aspects all have potentially important implications for future research, as well as for how athletes and coaches utilise caffeine around competition, both of which are explored in depth here.


Assuntos
Cafeína/farmacologia , Modelos Biológicos , Substâncias para Melhoria do Desempenho/farmacologia , Receptores Acoplados a Proteínas-G/efeitos dos fármacos , Paladar , Antecipação Psicológica , Desempenho Atlético , Variação Biológica Individual , Cafeína/administração & dosagem , Cafeína/química , Carboidratos/administração & dosagem , Carboidratos/farmacologia , Sinais (Psicologia) , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/fisiologia , Humanos , Modelos Psicológicos , Antissépticos Bucais , Substâncias para Melhoria do Desempenho/química , Receptores Acoplados a Proteínas-G/fisiologia , Percepção Gustatória/genética
11.
Anim Reprod Sci ; 208: 106120, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31405478

RESUMO

Intra-partum asphyxia is the most common non-infectious etiology limiting the performance of neonate piglets. Previous studies indicate caffeine (orally and subcutaneously) reverses the effects of intra-partum asphyxia in neonate piglets. In this study, there was investigation of whether use of a novel therapeutic protocol for administering caffeine subcutaneously to pregnant sows would improve the newborn piglets' vitality, physio-metabolic profiles and body weight gain. Sows were randomly divided into two groups (n = 10 each). Caffeine or NaCl 0.9% was administered 2 days pre-farrowing. Physio-metabolic profiles were measured using blood from the anterior vena cava. The vitality of piglets was evaluated immediately after birth. Piglets (n = 180) were weighed at birth and on days 7, 14 and 21 of lactation. Caffeine positively affected the vitality of the piglets, as indicated by greater vitality scores than that for the control group (8.72 ±â€¯0.12 compared with 7.28 ±â€¯0.16, P < 0.001). Metabolic values were similar between groups, but pO2 values were greater in the piglets with greater vitality scores treated with caffeine (19.10 ±â€¯0.82 compared with 14.49 ±â€¯1.42, P < 0.01), indicating increased respiratory rates. Body weight gain at day 21 was greater in the piglets treated with caffeine that had greater vitality scores than the control piglets having greater vitality scores (6.87 ±â€¯0.18 compared with 6.52 ±â€¯0.25 kg, P < 0.05). Caffeine administration before birth improves the vitality and respiratory capacity of piglets, increasing their adaptation to extra-uterine environment.


Assuntos
Animais Recém-Nascidos/fisiologia , Cafeína/farmacologia , Suínos , Ganho de Peso/efeitos dos fármacos , Ração Animal/análise , Animais , Cafeína/administração & dosagem , Estimulantes do Sistema Nervoso Central/administração & dosagem , Estimulantes do Sistema Nervoso Central/farmacologia , Dieta/veterinária , Feminino , Gravidez , Prenhez
12.
Nutrients ; 11(8)2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31443220

RESUMO

BACKGROUND: The main goal of this study was to assess the acute effects of the intake of 9 and 11 mg/kg/ body mass (b.m.) of caffeine (CAF) on maximal strength and muscle endurance in athletes habituated to caffeine. METHODS: The study included 16 healthy strength-trained male athletes (age = 24.2 ± 4.2 years, body mass = 79.5 ± 8.5 kg, body mass index (BMI) = 24.5 ± 1.9, bench press 1RM = 118.3 ± 14.5 kg). All participants were habitual caffeine consumers (4.9 ± 1.1 mg/kg/b.m., 411 ± 136 mg of caffeine per day). This study had a randomized, crossover, double-blind design, where each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 9 mg/kg/b.m. (CAF-9) and 11 mg/kg/b.m. (CAF-11) of caffeine. In each experimental session, participants underwent a 1RM strength test and a muscle endurance test in the bench press exercise at 50% 1RM while power output and bar velocity were measured in each test. RESULTS: A one-way repeated measures ANOVA revealed a significant difference between PLAC, CAF-9, and CAF-11 groups in peak velocity (PV) (p = 0.04). Post-hoc tests showed a significant decrease for PV (p = 0.04) in the CAF-11 compared to the PLAC group. No other changes were found in the 1RM or muscle endurance tests with the ingestion of caffeine. CONCLUSION: The results of the present study indicate that high acute doses of CAF (9 and 11 mg/kg/b.m.) did not improve muscle strength nor muscle endurance in athletes habituated to this substance.


Assuntos
Atletas , Cafeína/administração & dosagem , Café , Comportamento Alimentar , Força Muscular/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Adulto , Cafeína/efeitos adversos , Estudos Cross-Over , Método Duplo-Cego , Humanos , Masculino , Polônia , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
13.
BMC Cancer ; 19(1): 689, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31307409

RESUMO

BACKGROUND: While multiagent chemotherapy has dramatically improved the prognosis of sarcoma, the novel chemotherapeutics have hardly developed over the past 30 years. Caffeine can induce apoptosis, delays in cell cycle progression and can enhance the cytocidal effects of anti-cancer agents. Citrate has been reported to enhance the cytocidal effect of cisplatin in gastric cancer in vitro. However its effect in sarcoma cells had not been reported. METHODS: This study was designed to evaluate whether the addition of caffeine, citrate, or caffeine citrate to cisplatin improved its cytocidal effect (cell survival, proliferation, and apoptosis) on human osteosarcoma (HOS), human fibrosarcoma (HT1080) and murine osteosarcoma (LM8) cell lines. We also tested the various combinations in a mouse heterotopic transplantation model in vivo. In cell survival assay, combination index (CI) of caffeine citrate was calculated as a combination of anhydrous caffeine and citric acid, and the synergy was evaluated (CI < 1.0). RESULTS: In all cell lines, cisplatin combined with caffeine citrate significantly reinforced the anticancer effect compared with cisplatin alone, combination of cisplatin and anhydrous caffeine, and combination of cisplatin and citric acid. Moreover, CI was < 1.0 in all conditions. The anticancer agent reinforcement effect of caffeine citrate was synergy of anhydrous caffeine and citric acid. In cell proliferation and cell cycle assay revealed that caffeine citrate had most strong effect as a combination drug than caffeine and citric acid in inducing G0/G1 cell-cycle arrest with subsequent suppressed cell proliferation. In mitochondrial depolarization and caspase 3/7 activity assay revealed that caffeine citrate had most strong effect as a combination drug than caffeine and citric acid in apoptosis associated with decreased mitochondrial membrane potential. In vivo, three different drug concentrations were tested, and cisplatin combined with caffeine citrate was found to have the strongest antitumor effect. CONCLUSIONS: This is the first report demonstrating that caffeine citrate has a significantly greater potentiating effect on cisplatin than adding either caffeine or citric acid. The combination of cisplatin with caffeine citrate is a novel treatment that might hold promise for improving the outcome of osteosarcoma and fibrosarcoma, which up till now has generally not responded well to chemotherapy.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Cafeína/uso terapêutico , Estimulantes do Sistema Nervoso Central/uso terapêutico , Cisplatino/uso terapêutico , Citratos/uso terapêutico , Quimioterapia Combinada , Fibrossarcoma/tratamento farmacológico , Osteossarcoma/tratamento farmacológico , Animais , Antineoplásicos/administração & dosagem , Apoptose/efeitos dos fármacos , Cafeína/administração & dosagem , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/administração & dosagem , Cisplatino/administração & dosagem , Citratos/administração & dosagem , Sinergismo Farmacológico , Feminino , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Camundongos Nus , Resultado do Tratamento , Carga Tumoral , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Nutrients ; 11(7)2019 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-31330804

RESUMO

The aim was to evaluate the effect of caffeine (CAF) and extra virgin coconut oil (CO), isolated or combined, on running performance in runners. Methods: A randomized, placebo-controlled, and crossover study was conducted with thirteen recreational runners aged 18-40. All volunteers performed a 1600 m time trial at a 400 m track, each ingesting four different substances: (1) placebo (water), (2) decaffeinated coffee plus isolated CAF (DECAF + CAF), (3) decaffeinated coffee plus isolated CAF plus soy oil (DECAF + CAF + SO), and (4) decaffeinated coffee plus isolated CAF plus extra virgin coconut oil (DECAF + CAF + CO). The substances were ingested 60 min before the trials, the order of the situations was randomized, and there were one-week intervals between them. At the end of the trials, the Borg scale was applied to evaluate the rating of perceived exertion (RPE) and the time was measured. Results: Our data did not show differences in running time among the trials (placebo: 7.64 ± 0.80, DECAF + CAF: 7.61 ± 1.02, DECAF + CAF + SO: 7.66 ± 0.89, and DECAF + CAF + CO: 7.58 ± 0.74 min; p = 0.93), nor RPE (placebo: 6.15 ± 2.03, DECAF + CAF: 6.00 ± 2.27, DECAF + CAF + SO: 6.54 ± 2.73, and DECAF + CAF + CO: 6.00 ± 2.45 score; p = 0.99). Lactate concentrations (placebo: 6.23 ± 2.72, DECAF + CAF: 4.43 ± 3.77, DECAF + CAF + SO: 5.29 ± 3.77, and DECAF + CAF + CO: 6.17 ± 4.18 mmol/L; p = 0.55) also was not modified. Conclusion: Our study shows that ingestion of decaffeinated coffee with the addition of isolated CAF and extra virgin CO, either isolated or combined, does not improve 1600 m running times, nor influence RPE and lactate concentrations in recreational runners. Thus, combination of coffee with CO as a pre-workout supplement seems to be unsubstantiated for a short-distance race.


Assuntos
Cafeína/administração & dosagem , Cafeína/farmacologia , Óleo de Coco/administração & dosagem , Óleo de Coco/farmacologia , Recreação , Corrida , Adolescente , Adulto , Estudos Cross-Over , Suplementos Nutricionais , Humanos , Fatores de Tempo , Adulto Jovem
15.
J Strength Cond Res ; 33(9): 2308-2320, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31343547

RESUMO

Winwood, PW, Pritchard, HJ, Wilson, D, Dudson, M, and Keogh, JWL. The competition-day preparation strategies of strongman athletes. J Strength Cond Res 33(9): 2308-2320, 2019-This study provides the first empirical evidence of the competition-day preparation strategies used by strongman athletes. Strongman athletes (n = 132) (mean ± SD: 33.7 ± 8.1 years, 178.2 ± 11.1 cm, 107.0 ± 28.6 kg, 12.8 ± 8.0 years general resistance training, 5.9 ± 4.8 years strongman implement training) completed a self-reported 4-page internet survey on their usual competition-day preparation strategies. Analysis of the overall group and by sex, age, body mass, and competitive standard was conducted. Ninety-four percent of strongman athletes used warm-ups in competition, which were generally self-directed. The typical warm-up length was 16.0 ± 8.9 minutes, and 8.5 ± 4.3 minutes was the perceived optimal rest time before the start of an event. The main reasons for warming up were injury prevention, to increase activation, and increase blood flow/circulation, temperature, and heart rate. Athletes generally stated that competition warm-ups were practiced in training. Dynamic stretching, foam rolling, and myofascial release work were performed during warm-ups. Warm-up intensity was monitored using the rate of perceived exertion, perceived speed of movement, and training load (as a percentage of 1 repetition maximum). Cognitive strategies were used to improve competition performance, and psychological arousal levels needed to increase or be maintained in competition. Electrolyte drinks, caffeine, and preworkout supplements were the commonly used supplements. These data will provide strongman athletes and coaches some insight into common competition-day preparation strategies, which may enhance competition performances. Future research could compare different competition-day preparation strategies in an attempt to further improve strongman competition performance and injury prevention.


Assuntos
Comportamento Competitivo , Esportes , Exercício de Aquecimento , Adulto , Nível de Alerta , Bebidas/estatística & dados numéricos , Cafeína/administração & dosagem , Suplementos Nutricionais/estatística & dados numéricos , Eletrólitos/administração & dosagem , Feminino , Frequência Cardíaca , Humanos , Masculino , Massagem , Exercícios de Alongamento Muscular , Esforço Físico , Treinamento de Resistência , Descanso , Esportes/fisiologia , Esportes/psicologia , Inquéritos e Questionários , Adulto Jovem
17.
Nutrients ; 11(6)2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31242545

RESUMO

Mixed martial arts (MMA) is a combat sport where competitors utilize strikes (punches, kicks, knees, and elbows) and submission techniques to defeat opponents in a cage or ring. The aim of this study was to investigate the effect of acute caffeine ingestion on punching performance by professional MMA athletes. The study used a double-blind, counterbalanced, crossover design. Eleven professional MMA competitors (27.6 ± 4.3 years and 83.5 ± 7.8 kg of body weight) ingested a dose of caffeine (5 mg·kg-1) or placebo 60 min prior to three sets of punching. Each set consisted of 15 s, at which participants were asked to perform straight punches with maximum strength and frequency with his dominant arm. After each set, a 45 s recovery time was applied. Using a force transducer attached to a cushioned plate, the punch frequency, and mean and maximal punch force was measured. The readiness to invest in both physical (RTIPE) and mental (RTIME) effort was assessed prior to the protocol, and the rating of perceived exertion (RPE) was recorded after. Caffeine ingestion did not result in increased punching frequency, mean and maximum punch force, RTIPE, RTIME, and RPE when compared to the placebo condition. Based on these results, acute caffeine ingestion did not improve punching performance in professional MMA athletes.


Assuntos
Atletas , Desempenho Atlético , Cafeína/administração & dosagem , Estimulantes do Sistema Nervoso Central/administração & dosagem , Artes Marciais , Adulto , Brasil , Estudos Cross-Over , Método Duplo-Cego , Nível de Saúde , Humanos , Masculino , Força Muscular , Fatores de Tempo , Adulto Jovem
18.
J Cardiovasc Magn Reson ; 21(1): 33, 2019 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-31230593

RESUMO

BACKGROUND: Adenosine is used in stress perfusion cardiac imaging to reveal myocardial ischemia by its vasodilator effects. Caffeine is a competitive antagonist of adenosine. However, previous studies reported inconsistent results about the influence of caffeine on adenosine's vasodilator effect. This study assessed the impact of caffeine on the myocardial perfusion reserve index (MPRI) using adenosine stress cardiovascular magnetic resonance imaging (CMR). Moreover, we sought to evaluate if the splenic switch-off sign might be indicative of prior caffeine consumption. METHODS: Semiquantitative perfusion analysis was performed in 25 patients who underwent: 1) caffeine-naïve adenosine stress CMR demonstrating myocardial ischemia and, 2) repeat adenosine stress CMR after intake of caffeine. MPRI (global; remote and ischemic segments), and splenic perfusion ratio (SPR) were assessed and compared between both exams. RESULTS: Global MPRI after caffeine was lower vs. caffeine-naïve conditions (1.09 ± 0.19 vs. 1.24 ± 0.19; p <  0.01). MPRI in remote myocardium decreased by caffeine (1.24 ± 0.19 vs. 1.49 ± 0.19; p <  0.001) whereas MPRI in ischemic segments (0.89 ± 0.18 vs. 0.95 ± 0.23; p = 0.23) was similar, resulting in a lower MPRI ratio (=remote/ischemic segments) after caffeine consumption vs. caffeine-naïve conditions (1.41 ± 0.19 vs. 1.64 ± 0.35, p = 0.01). The SPR was unaffected by caffeine (SPR 0.38 ± 0.19 vs. 0.38 ± 0.18; p = 0.92). CONCLUSION: Caffeine consumption prior to adenosine stress CMR results in a lower global MPRI, which is driven by the decreased MPRI in remote myocardium and underlines the need of abstinence from caffeine. The splenic switch-off sign is not affected by prior caffeine intake.


Assuntos
Adenosina/administração & dosagem , Cafeína/administração & dosagem , Circulação Coronária/efeitos dos fármacos , Imagem Cinética por Ressonância Magnética , Isquemia Miocárdica/diagnóstico por imagem , Imagem de Perfusão do Miocárdio/métodos , Antagonistas de Receptores Purinérgicos P1/administração & dosagem , Vasodilatação/efeitos dos fármacos , Vasodilatadores/administração & dosagem , Idoso , Cafeína/efeitos adversos , Feminino , Humanos , Hiperemia , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/fisiopatologia , Valor Preditivo dos Testes , Estudos Prospectivos , Antagonistas de Receptores Purinérgicos P1/efeitos adversos , Reprodutibilidade dos Testes
19.
Nutrients ; 11(7)2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31252655

RESUMO

BACKGROUND: Previously studies confirm ergogenic effects of caffeine (CAF); however there is no available scientific data regarding the influence of acute CAF intake on power output in athletes habitually consuming CAF. The main goal of this study was to assess the acute effect of 3, 6, 9 mg/kg/b.m. doses of CAF intake on power output and bench press bar velocity in athletes habitually consuming CAF. METHODS: The study included 15 healthy strength-trained male athletes (age = 26.8 ± 6.2 years, body mass = 82.6 ± 9.7 kg; BMI = 24.8 ± 2.7; bench press 1RM = 122.3 ± 24.5 kg). All participants were habitual caffeine consumers (5.2 ± 1.2 mg/kg/b.m.; 426 ± 102 mg of caffeine per day). This study had a randomized, crossover, double-blind study design where each participant performed four different experimental sessions, with one week interval between each trial. In every experimental session participants performed bench press, three sets of five repetitions at 50% 1RM. The power output and bar velocity assessments under four different conditions: a placebo (PLAC), and three doses of caffeine ingestion: 3 mg/kg/b.m. (CAF-3), 6 mg/kg/b.m. (CAF-6) and 9 mg/kg/b.m. (CAF-9). RESULTS: The statistical significance was set at p < 0.05. The repeated measures ANOVA between PLAC and CAF-3; CAF-6; CAF-9 revealed no statistically significant differences in power output and velocity of the bar during the bench press exercise. A large effect size (ES) in mean power-output was found between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak power-output was found between PLAC and CAF-6 in Set 2, and between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak velocity was found between PLAC and CAF-9 in Sets 1-3. CONCLUSION: The results of the present study indicate that acute doses of CAF before exercise does not have a significant effect on power output and bar velocity in a group of habitual caffeine users.


Assuntos
Atletas , Cafeína/administração & dosagem , Estimulantes do Sistema Nervoso Central/administração & dosagem , Força Muscular/efeitos dos fármacos , Treinamento de Resistência , Adulto , Estudos Cross-Over , Método Duplo-Cego , Hábitos , Humanos , Masculino , Polônia , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
20.
Nutrients ; 11(5)2019 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31035471

RESUMO

The consumption of high levels of dietary caffeine has increased in children and adolescents. Human and animal studies have shown that chronic intake of high doses of caffeine affects serum glucocorticoid levels. Given that glucocorticoids play a role in peripubertal organ growth and development, chronic high doses of caffeine during puberty might impair maturation of the adrenal glands. To evaluate any effects of caffeine exposure on growing adrenal glands, 22-day-old male (n = 30) and female Sprague Dawley rats (n = 30) were divided into three groups (n = 10/group); group 1 received tap water (control) and groups 2 and 3 received water containing 120 and 180 mg/kg/day caffeine, respectively, via gavage for 4 weeks. At the end of the experiment, adrenal glands were weighed and processed for histological analysis. Relative adrenal weights increased in both groups of caffeine-fed males and females, whereas absolute weights were decreased in the females. In the female caffeine-fed groups the adrenal cortical areas resembled irregularly arranged cords and the medullary area was significantly increased, whereas no such effects were seen in the male rats. Our results indicate that the harmful effects of caffeine on the adrenal glands of immature rats differ between females and males. Although female rats seemed to be more susceptible to damage based on the changes in the microarchitecture of the adrenal glands, caffeine affected corticosterone production in both female and male rats. In addition, increased basal adrenocorticotropic hormone levels in caffeine-fed groups may reflect decreased cortical function. Therefore, caffeine may induce an endocrine imbalance that disturbs the establishment of the hypothalamo-pituitary adrenal axis during puberty, thereby leading to abnormal stress responses.


Assuntos
Glândulas Suprarrenais/efeitos dos fármacos , Cafeína/efeitos adversos , Maturidade Sexual , Glândulas Suprarrenais/patologia , Hormônio Adrenocorticotrópico/sangue , Animais , Cafeína/administração & dosagem , Corticosterona/sangue , Relação Dose-Resposta a Droga , Feminino , Masculino , Tamanho do Órgão , Ratos , Ratos Sprague-Dawley
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