Acute physiological response to indoor cycling with and without hydration; case and self-control study.

INTRODUCTION: Oral rehydration drinks help maintain physical capacity and hydration during exercise. OBJECTIVE: Evaluate, in a case and self-control study, the effectiveness of three hydration and exercise protocols on work capacity and physical and psychosomatic stress during indoor cycling (InC). METHODS: 14 middle-aged eutrophic men participated in three controlled randomly and not sequentially hydration (~278 mL 6/c 15 min) and exercise (InC/90 min) protocols: No liquids, plain water, or sports drinks (SD). The response variables were: Body temperature (BT), heart rate (HR), and mean blood pressure (MBP). The covariables: Distance traveled (DT), ergometer resistance (R), body fat (BF), difference in body weight between tests (rBW), and age of the participants. The differences between protocols were evaluated using GLM Repeated Measures, the independence of associations by multiple linear regression. RESULTS: In non-liquids, the subjects showed higher BT, HR, and MBP than when they drank plain water or SD (p < 0.01). Work capacity was the same in the three hydration protocols. BT was the most sensitive variable detected by the hydration status of the subjects. 34%, 99%, and 21% of the associated variance to HR, MBP, and BT was explained by DT + BT, BT + BF, and ΔBW + age + R + DT + BF, respectively. CONCLUSIONS: Liquid intake with or without electrolytes does not affect work capacity, and they are equally effective as hydration sources during =?90 min of InC at strong and very strong intensities. Body temperature is the most sensitive variable detected by the subject's hydration status during exercise.

Introducción: Las bebidas de re-hidratación oral ayudan a mantener la capacidad física y el nivel de hidratación durante el ejercicio. Objetivo: Evaluar en un estudio de casos y autocontroles la efectividad de tres protocolos de hidratación y ejercicio sobre la capacidad de trabajo, estrés físico y psicosomático durante el ciclismo de sala (CiS). Métodos: 14 varones eutróficos de mediana edad participaron de manera aleatoria y no consecutiva en tres protocolos de hidratación controlada (~278 mL 6/c 15 min) y ejercicio (CiS/90 min): No líquidos, agua corriente o bebida deportiva (BD). Las variables respuesta fueron: Temperatura corporal (TC), frecuencia cardiaca (FC) y presión sanguínea media (PSM). Las covariables: distancia recorrida (DR), resistencia del ergómetro (R) grasa corporal (GC), pérdida de peso al final del ejercicio ( PC) y edad de los participantes. Las diferencias entre los protocolos fueron evaluadas por GLM de Medidas Repetidas, la independencia de las asociaciones por regresión lineal múltiple. Resultados: En no líquidos, los sujetos presentaron mayor TC, FC y PSM que cuando ingirieron agua corriente o BD (p < 0,01). La capacidad de trabajo fue igual en los tres protocolos de hidratación. La TC fue la variable más sensible que detectó el estado de hidratación de los sujetos. El 34%, 99% y 21% de la varianza asociada a FC, PSM y TC lo explicaron DR + TC, TC + GC, y ?PC + edad + R + DR + GC respectivamente. Conclusiones: La ingesta de líquidos con o sin electrolitos no afecta la capacidad de trabajo y son igualmente efectivos como medios de hidratación durante =?90 min de Cis a intensidades pesadas y muy pesadas. La TC es la variable más sensible que detecta el estado de hidratación de los sujetos durante el ejercicio.

Effects of dietary Spirulina on vascular reactivity.

There are several reports suggesting that Spirulina (Arthrospira) may have a beneficial effect in the prevention of cardiovascular diseases. Here we review the results of studies on the effects of dietary Spirulina on the vasomotor reactivity of aortic rings excised from either lean or obese Wistar rats. We also review preliminary results on the effects of Spirulina intake on plasma lipids and blood pressure in humans. The results of the former studies strongly suggest that Spirulina induces a tone-related increase in the synthesis/release of nitric oxide by the endothelium as well as an increase in the synthesis/release of a vasodilating cyclooxygenase-dependent metabolite of arachidonic acid and/or a decrease in the synthesis/release of a vasoconstricting eicosanoid by the endothelium. In humans, Spirulina maxima intake decreases blood pressure and plasma lipid concentrations, especially triacylglycerols and low-density lipoprotein-cholesterol, and indirectly modifies the total cholesterol and high-density lipoprotein-cholesterol values.

Effects of single sessions of low-intensity continuous and moderate-intensity intermittent exercise on blood lipids in the same endurance runners.

The factors responsible for the acute effects of exercise on blood lipids are not well known, and there have been few studies comparing different kinds of exercise in the same population. The concentration of blood lipids was evaluated in this study at the end and at post-24h of two 14km/90min single exercise sessions: continuous exercise (CE) at 44.5+/-5.6% VO(2max) and intermittent exercise (IE) at 39-72% VO(2max), in subjects with high levels of aerobic training. Fourteen male athletes (endurance runners) took part in this study and each completed a 24h dietary record. The O(2) uptake and CO(2) production were recorded, and blood lactate and blood lipids were measured. The results showed that triacylglycerols were not modified by any kind of exercise. Total cholesterol was increased at the end of both exercises: 7.04% for CE (p<0.001) and 4.23% for IE (p=0.001). High-density lipoprotein cholesterol was increased at the end of IE: 11.38% (p=0.03) and low-density lipoprotein cholesterol was increased only at the end of CE: 7.45% (p=0.006). The increase of lipids for CE was negatively correlated with aerobic fitness indicators (heart rate and %HRmax at lactate threshold), and was positively associated with energy expenditure. For IE, %HRmax and lactate were negatively correlated, and the respiratory exchange ratio was positively correlated, with the lipid increase. We conclude that in trained male athletes, a 14km run in 90min induced different changes of lipid profile if the exercise was done continuously or intermittently, and that in CE the extent of these increases was influenced by aerobic fitness.

Effects of the ethanolic extract of Spirulina maxima on endothelium dependent vasomotor responses of rat aortic rings.

Dietary Spirulina decreases, endothelium-dependently, the responses to vasoconstrictor agonists and increases the endothelium-dependent, agonist-induced, vasodilator responses of rat aorta rings. The aim of this study was to analyze, in vitro, the effects of a raw ethanolic extract of Spirulina maxima on the vasomotor responses of rat aortic rings to phenylephrine and to carbachol. On rings with endothelium, the extract produced the following effects: (a) a concentration-dependent (60-1000 microg/ml) decrease of the contractile response to phenylephrine; (b) a rightward shift and a decrease in maximal developed tension, of the concentration--response curve to phenylephrine; (c) a concentration dependent relaxation of phenylephrine-precontracted rings. These effects were blocked by L-NAME, and not modified by indomethacin. The extract had no effect on the concentration-response curve to carbachol of rings with endothelium. On endothelium-denuded rings the extract caused a significant rightward shift of the concentration response curve to phenylephrine without any effect on maximal tension development. In the presence of the extract, indomethacin induced a marked decrease in the maximal phenylephrine-induced tension of endothelium-denuded rings. These results suggest that the extract increases the basal synthesis/release of NO by the endothelium and, also, the synthesis/release of a cyclooxygenase-dependent vasoconstricting prostanoid by vascular smooth muscle cells.

Studies on the preventive effect of Spirulina maxima on fatty liver development induced by carbon tetrachloride, in the rat.

The aim of the present work was to assess if the feeding of either the oil extract of Spirulina maxima or of its defatted fraction would prevent fatty liver development, induced in rats by a single intraperitoneal dose of carbon tetrachloride (CCl4). Liver and serum lipids were evaluated 4 days after treatment with this agent. Concentration of liver lipids did not differ in rats fed on a purified diet either without or with one of the fractions of Spirulina, except for total cholesterol, which showed a slight increase in the group receiving the oil extract of Spirulina. However, after CCl4 treatment, liver total lipids and triacylglycerols were significantly lower in rats fed on a diet containing any fraction of Spirulina (defatted or the oil fraction) than in rats without Spirulina in their diet. Furthermore, the increased liver cholesterol values, induced by CCl4 treatment, were not observed in rats receiving Spirulina. In addition, rats receiving whole Spirulina in their diet and treated only with the vehicle showed an increase in the percentage of HDL values. The changes in VLDL and LDL induced by CCl4 treatment were not observed in the whole Spirulina group. Furthermore, after CCl4 treatment the values of the liver microsomal thiobarbituric acid-reactive substances were lower in the whole Spirulina group than in the control group. These results support the potential hepatoprotective role of Spirulina.

Spirulina maxima prevents induction of fatty liver by carbon tetrachloride in the rat.

The aim of the present work was to assess the capacity of Spirulina maxima to prevent fatty liver development induced in rats by an intraperitoneal single dose (1 ml/kg) of carbon tetrachloride. Liver and serum lipids were quantified two or four days after treatment with this agent. Liver lipid concentration did not differ in rats fed on a purified diet with or without Spirulina. However, after carbon tetrachloride treatment, liver triacylglycerols were significantly lower in rats fed on a diet with Spirulina 5% than in rats without Spirulina in their diet (P < 0.05). Furthermore, the increased liver cholesterol values, induced by carbon tetrachloride treatment, were not observed in rats that received Spirulina. These results support the potential hepatoprotective role of Spirulina.

Effects of dietary Spirulina maxima on endothelium dependent vasomotor responses of rat aortic rings.

The aim of this study was to evaluate the effects of Spirulina maxima on vasomotor responses of aorta rings from male Wistar rats fed on a purified diet. For this purpose, the animals (weighing 200-240 g) were allocated randomly in two groups. One receiving purified control diet (A) and the other receiving purified diet containing 5% Spirulina (B). Purified diets were according to American Institute of Nutrition guidelines and adjusted to Spirulina protein content. All animals were fed (20 g/day/rat) during two weeks, receiving water ad libitum and 12 h. light-dark cycles. Spirulina maxima effects were evaluated by concentration-response (CR) curves of aorta rings with or without endothelium to phenylephrine (PE), both in presence and absence of indomethacin (Indom) or indomethacin plus L-NAME (Indom. + L-NAME), and to carbachol (CCh). Aorta rings with endothelium from group B showed, relative to corresponding rings from group A: 1) a significant decrease in the maximal tension developed in response to PE. 2) this decrease was reverted by Indom. 3) Indom. + L-NAME induced an additional increase in the contractile responses to PE. 4) a significant shift to the left of the CR curve to CCh. No significant differences were observed in the tension developed in response to PE in rings without endothelium from either group. These results suggest that Spirulina maxima may decrease vascular tone by increasing the synthesis and release of both a vasodilating cyclooxygenase-dependent product of arachidonic acid and nitric oxide, as well as by decreasing the synthesis and release of a vasoconstricting eicosanoid from the endothelial cells.