Consumption of energy drinks on cardiovascular and metabolic response and performance. Is there an effect? / Consumo de bebidas energéticas sobre la respuesta cardiovascular, metabólica y rendimiento. ¿Hay efecto?

Over the years, the search for nutritional strategies that promote improved sports performance has increased. Among the available options, energy drinks appear as potential nutritional resources for this purpose, because they offer, in addition to caffeine, substances that act synergistically to improve performance, such as taurine, carbohydrates, amino acids, vitamins and minerals, promoting improved performance for both amateur and professional athletes. The aim of the study was to verify the effects of ingesting energy drinks with (ED1) and without carbohydrates (ED0) containing 2 mg·kg-1 of caffeine, and a decaffeinated placebo (PL) on cardiovascular, metabolic and performance parameters during cycling. Twelve male cyclists (age = 24.4 ± 6.6 years old) volunteered to participate in this study. The protocol consisted of three experimental sessions of 60 min of continuous cycling (65-75% of VO2maxE) followed by time-trial 6 km. The subjects ingested ED1, ED0 or a placebo drink (PL) 40 min before beginning the exercise. The heart rate (HR), blood pressure (BP), plasma glucose and lactate concentrations, and the time taken to complete the 6 km time-trial were evaluated. The time taken to complete the time-trial was significantly higher (p < 0.05) in the PL group than in the groups ED1 and ED0. This time significantly decreased after the ED1 consumption relative to that for the ED0 consumption. Heart rate, systolic and diastolic arterial pressure and in the plasma glucose and lactate concentrations were similar in all the considered groups. These results demonstrate that ED1 consumption appears to be more effective at maximizing performance during the last 6 km.(AU)

Con el paso de los años, se ha incrementado la búsqueda de estrategias nutricionales que promuevan un mejor rendimiento deportivo. Entre las opciones disponibles, las bebidas energéticas aparecen como potenciales recursos nutricionales para este fin, pues ofrecen, además de la cafeína, sustancias que actúan sinérgicamente para mejorar el rendimiento, como taurina, carbohidratos, aminoácidos, vitaminas y minerales, promoviendo un mejor rendimiento para atletas tanto aficionados como profesionales. El objetivo del estudio fue verificar los efectos de la ingestión de bebidas energéticas con (ED1) y sin carbohidratos (ED0) que contienen 2 mg · kg-1 de cafeína y un placebo descafeinado (PL) sobre los parámetros cardiovasculares, metabólicos y de rendimiento durante el ciclismo. Doce ciclistas varones (edad = 24,4 ± 6,6 años) participaron voluntariamente en este estudio. El protocolo consistió en tres sesiones experimentales de 60 min de ciclismo continuo (65-75% del VO2max) seguidas de una prueba contrarreloj de 6 km. Los sujetos ingirieron ED1, ED0 o una bebida placebo (PL) 40 minutos antes de comenzar el ejercicio. Se registró la frecuencia cardíaca (FC), la presión arterial (PA), las concentraciones plasmáticas de glucosa y lactato y el tiempo necesario para completar la prueba contrarreloj de 6 km. El tiempo necesario para completar la contrarreloj en el grupo PL fue significativamente mayor (p <0,05) que en los grupos ED1 y ED0. Este tiempo disminuyó significativamente después del consumo de ED1 en relación con el consumo de ED0. La frecuencia cardíaca, la presión arterial sistólica y diastólica y las concentraciones plasmáticas de glucosa y lactato fueron similares en todos los grupos. Estos resultados demuestran que el consumo de ED1 parece ser más eficaz para maximizar el rendimiento durante los últimos 6 km.(AU)

Effects of Different Conditioning Activities on 100-m Dash Performance in High School Track and Field Athletes.

This study compared the effects of different conditioning activities on the 100-m dash performance of 11 male, high school track and field athletes (mean age = 16.3; SD = 1.2 years). Participants performed a 100-m dash seven minutes after each of four randomized conditioning protocols, with each condition and 100-m dash separated by 3-10 days. The conditioning protocols were (a) control, no conditioning activity; (b) weighted plyometric, three sets of 10 repetitions of alternate leg bounding with additional load of 10% of the body mass; (c) free sprint, two 20-m sprints; and (d) resisted sprint (RS), two 20-m resisted sprints using an elastic tubing tool. We obtained session ratings of perceived exertion (SRPE) immediately after each conditioning protocol. There were no significant differences between any of the three experimental conditioning activities on 100-m sprint time, but the RS protocol improved 100-m sprint time compared with the control (no conditioning) protocol ( p < .001). The RS also led to greater sprint velocity and higher SRPE compared with the control condition ( p < .01). There was no significant association between SRPE and 100-m performance ( p = .77, r = .05). These results suggest a benefit for young male track and field athletes to the elastic tubing warm-up activities prior to the 100-m dash.

[Effects of glycemic index on energy balance]. / Efeitos do índice glicêmico no balanço energético.

The prevalence of obesity has increased over the last decades. Associated to this, there has been observed a chance in the dietetic pattern of the population in general, related to the increase in carbohydrate consumption. According to some authors, the glycemic index (GI) of food may affect body composition and body weight. The purpose of this review was to evaluate the effects of GI on appetite, satiety, and body composition. Based on the scientific evidences reviewed, it was possible to verify that the majority of the studies that observed a positive effect of GI in that matter have a lot of methodological limitations. Well-designed studies have not observed any benefit of GI on these parameters. Therefore, it is concluded that GI has little application in clinical practice, as a useful tool to control satiety, reduce appetite, and consequently, to reduce the prevalence of obesity.

Efeitos do índice glicêmico no balanço energético / Effects of glycemic index on energy balance

A prevalência da obesidade vem crescendo nas últimas décadas. Associado a este fato, tem-se observado uma mudança no padrão dietético da população em geral, no que diz respeito a um maior consumo de carboidratos. Segundo alguns autores, o índice glicêmico (IG) dos alimentos afeta a composição e o peso corporal. A presente revisão de literatura teve como objetivo avaliar os efeitos do IG sobre apetite, saciedade e composição corporal. A partir das evidências científicas analisadas, foi possível constatar que a maioria dos estudos que atribuem efeitos positivos ao IG é cercada de limitações metodológicas. Estudos bem delineados não observaram benefícios do IG sobre os parâmetros citados acima. Diante disso, conclui-se que o IG apresenta pouca aplicabilidade na prática clínica, como uma ferramenta capaz de controlar a saciedade, reduzir o apetite e, conseqüentemente, a prevalência de obesidade.

The prevalence of obesity has increased over the last decades. Associated to this, there has been observed a chance in the dietetic pattern of the population in general, related to the increase in carbohydrate consumption. According to some authors, the glycemic index (GI) of food may affect body composition and body weight. The purpose of this review was to evaluate the effects of GI on appetite, satiety, and body composition. Based on the scientific evidences reviewed, it was possible to verify that the majority of the studies that observed a positive effect of GI in that matter have a lot of methodological limitations. Well-designed studies have not observed any benefit of GI on these parameters. Therefore, it is concluded that GI has little application in clinical practice, as a useful tool to control satiety, reduce appetite, and consequently, to reduce the prevalence of obesity.