Heart Rate Variability In Athletes And Nonathletes At Rest And During Head-up Tilt.

The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV), differs during supine rest and head-up tilt (HUT) when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S) and 10 trained cyclists (C) were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70 masculine HUT. The major aerobic capacity of athletes was expressed by higher values of VO2 at anaerobic threshold and peak conditions (P < 0.05). At rest the athletes had lower heart rates (P < 0.05) and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians): 59.1 ms (S) vs 89.9 ms (C), P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians): 55.7 ms (S) vs 69.7 ms (C), P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups.38639-4

Chronically administered acetaminophen and the ischemia/reperfused myocardium

Male and female Hartley strain guinea pigs weighing 280 10 g were given acetaminophen-treated water ad libitum for 10 days. Sham-treated control animals were given similar quantities of untreated tap water (vehicle-treated control group). On Day 10, hearts were extracted, instrumented, and exposed to an ischemia (low-flow, 20 min)/reperfusion protocol. Our objective was to compare and contrast ventricular function, coronary circulation, and selected biochemical and histological indices in the two treatment groups. Left ventricular developed pressure in the early minutes of reperfusion was significantly greater in the presence of acetaminophen, e.g., at I min, 40 +/- 4 vs 21 +/- 3 mmHg (P<0.05). Coronary perfusion pressure was significantly less from 3 to 40 min of reperfusion in the presence of acetaminophen. Creatine kinase release in vehicle-treated hearts rose from 42 +/- 14 (baseline) to 78 +/- 25 units/liter by the end of ischemia. Corresponding values in acetaminophen-treated hearts were 36 8 and 44 +/- 14 units/liter. Acetaminophen significantly (P < 0.05) attenuated release of creatine kinase. Chemiluminescence, an indicator of the in vitro production of peroxynitrite via the in vivo release of superoxide and nitric oxide, was also significantly attenuated by acetaminophen. Electron microscopy indicated a well-preserved myofibrillar ultrastructure in the postischemic myocardium of acetaminophen-treated hearts relative to vehicle-treated hearts (e.g., few signs of contraction bands, little or no evidence of swollen mitochondria, and well-defined light and dark bands in sarcomeres with acetaminophen; opposite with vehicle). We conclude that chronic administration of acetaminophen provides cardioprotection to the postischemic, reperfused rodent myocardium.228667468

Acetaminophen in the post-ischemia reperfused myocardium

Acetaminophen was administered acutely at the onset of reperfusion after 20 min of low-flow, global myocardial ischemia in isolated, perfused guinea pig hearts (Langendortf) to evaluate its influence in the postischemia, reperfused myocardium. Similarly prepared hearts were treated with vehicle or with uric acid (another phenol for comparison). Functionally, acetaminophentreated hearts (0.35 mM) achieved significantly greater recovery during reperfusion. For example, left ventricular developed pressures at 40 min reperfusion were 38 +/- 3, 27 +/- 3, and 20 +/- 2 in the presence of acetaminophen (P < 0.05, relative to the other two groups), vehicle, and uric acid, respectively. Coronary perfusion pressures and calculated coronary vascular resistances, in the acetaminophen-treated hearts, were significantly lower at the same time (e.g., coronary perfusion pressures in the three groups, respectively, were 40 +/- 2 [P < 0.05], 51 &PLUSMN; 3, and 65 &PLUSMN; 12 mm Hg). Under baseline, control conditions, creatine kinase ranged from 12-15 units/liter in the three groups. It increased to 35-40 units/liter (P &LT; 0.05) during ischemia but was significantly reduced by acetaminophen during reperfusion (e.g., 5.3 &PLUSMN; 0.8 units/liter at 40 min). Oxidant-mediated chemiluminescence in all three treatment groups during baseline conditions and ischemia was similar (i.e., approximately 1.5-2.0 min for peak luminescence to reach its half maximal value). It took significantly more time during reperfusion for the oxidation of luminol in the presence of acetaminophen (&GT;20 min, P &LT; 0.05) than in its absence (3-8 min in uric acid- and vehicle-treated hearts). These results suggest that administration of acetaminophen (0.35 mM), at the onset of reperfusion, provides anti-oxidant-mediated cardioprotection in the postischemia, reperfused myocardium.227111031103

Baroreceptor reflex and integrative stress responses in chronic fatigue syndrome

Objective: Altered cardiovascular responses to mental and postural stressors have been reported in chronic fatigue syndrome (CFS). This study examined whether those findings may involve changes in baroreceptor reflex functioning. Methods: Chronotropic baroreceptor reflex (by sequential analysis) and cardiovascular stress responses were recorded during postural (5-minute of active standing) and cognitive (speech task) stress testing in patients with CFS grouped into cases with severe (N = 21) or less severe (N = 22) illness, and in 29 matched control subjects. Results: Patients with CFS had a greater decline in baroreceptor reflex sensitivity (BRS) during standing, although only those with severe CFS were significantly different from the controls. Systolic blood pressure declined during standing in the control group but was maintained in the CFS patients. In contrast, the patients with less severe CFS had blunted increases in blood pressure during the speech task, which could not, however, be explained by inadequate inhibition of the baroreceptor reflex, with all groups showing an appropriate reduction in BRS during the task. Conclusions: These results indicate that in CFS, deficiencies in orthostatic regulation, but not in centrally mediated stress responses, may involve the baroreceptor reflex. This study also suggests that classifying patients with CFS on illness severity may discriminate between patients with abnormalities in peripheral vs. central mechanisms of cardiovascular stress responses.65588989

Heart rate variability in athletes and nonathletes at rest and during head-up tilt

The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV), differs during supine rest and head-up tilt (HUT) when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S) and 10 trained cyclists (C) were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70º HUT. The major aerobic capacity of athletes was expressed by higher values of <img src="/img/revistas/bjmbr/v38n4/Vo.gif">at anaerobic threshold and peak conditions (P < 0.05). At rest the athletes had lower heart rates (P < 0.05) and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians): 59.1 ms (S) vs 89.9 ms (C), P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians): 55.7 ms (S) vs 69.7 ms (C), P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups

Study Of Cardiorespiratory Variables At The Anaerobic Threshold (at) In Trained And Sedentary Subjects

The AT is a parameter which signals the moment of equilibrium loss between the supply and demand of oxygen during the performance of dynamic exercise(DE). This physiological parameter is dependent on to the type of physical training and has been used in the evaluation of aerobic capacity. This study aimed to analyze the cardiorespiratory variables at the moment of the AT. DE tests were applied using a continuous protocoKCP) up to physical exhaustion with direct measurement of the oxygen uptakeCv'Oa ). The studied groups included: 5 sedentary subjects(S); 5 long distance runners(LDR) and; 5 weight lifters(WL). The values (medians) of cardiorespiratory variables determined at the AT were as follows: a) O2 (mI/kg/min.)=18.5(S), 20(WL) and 29.9(LDR)(p<0.05 between LDR and the other groups); bjheart rate (HR-bpm)=120(S),120(WL),120(LDR);c)AHR from rest to the AT=+36(S),+42(WL), and+66(LDR)(p<0.05 between LDR and S); d) power(watts)=50(S),100(WL),100(LDR)(p<0.05 between LDR and S); e) ventilation (l/min)=34.1(S),35.9(WL),40(LDR). These data have shown the occurrence of prominent cardiorespiratory adaptations with increase of aerobic power in LDR group, when compared to the other studied groups (S and WD.Research support: FAEP-UNICAMP& FAPESP. [email protected]

La pasta Fresca, ripiena e gli gnocchi nella cucina della tradizione regionale.

La pasta fresca, ripiena e gli gnocchi rappresentano un'eccelleza della cucina regionale italiana. La storia, e la tecnica di produzione di fettuccine, lasagne, trofie, bigoli, maltagliati, pici, cavatelli, orecchiette,gnocchi di patate, zucca e semolino, tanto per citare alcuni esempi, costituiscono un grande patrimonio della nostra gastronomi

Cardiorespiratory Responses To Incremental Exercise In Young And Middle-aged Sedentary Men

The general behavior of cardiorespiratory responses during incremental exercise are well established. However, these responses can be influenced by factors such as age, gender, physical performance, genetic factors and others. The purpose of this study was to verify the peak oxygen uptake (%Oi peak), the peak workload and the venn'latory anaerobic threshold (AT) in two groups of brazilian sedentary men: Gl (n=15) x=2lyr and 02 (n=10) 55=53 yr. Dynamic exercise tests were applied in a cicloergometer (Quinton, in sitting position) using a continuous protocol up to physical exhaustion, with direct measuremment of the VOi (MMCSensormedics). The results (medians) for the groups were: 02 peak (ml/Kg/min)= 38(G1) and 27.3(02) (p<0.05); WL peak(Watts)= 212(01) and 163(02) (p<0.05); AT(%VO2 peak)= 64%(G1) and 67.2%(G2). These results have shown that during incremental exercises most of the studied parameters were higher in the younger group, with the exception of AT (%O2 peak) which showed differences not statiscally significant. Research support: FAEP-UNICAMP, FAPESP & CAPES, e-mail: [email protected]