Effect of Resistance Training on Blood Pressure and Autonomic Responses in Treated Hypertensives.

Trevizani, GA, Seixas, MB, Benchimol-Barbosa, PR, Vianna, JM, da Silva, LP, and Nadal, J. Effect of resistance training on blood pressure and autonomic responses in treated hypertensives. J Strength Cond Res 32(5): 1462-1470, 2018-This study evaluated the effect of resistance training (RT) on heart rate variability (HRV) and on blood pressure (BP) responses to acute and short-term exposure in treated hypertensive (HT) subjects. Twenty-one men participated in the study, 8 HT under drug treatment regimen and achieving adequate BP control before inclusion and 13 normotensive (NT). The RT protocol consisted of 12 sessions with eight exercises (leg extension, leg press, leg curl, bench press, seated row, triceps push-down, seated calf flexion, and seated arm curl) performed for two sets of 15-20 repetitions with 50% of one repetition maximum with 2-minute rest intervals in between sets, 3×/week. Heartbeat measurements were taken before and after RT, and BP was measured at the beginning and at the end of each session after 10-minute rest. The repeated measures analysis of variance (effect: group vs. training) evaluated BP and HRV responses. Effect size (ES) calculation measured the magnitude of the RT effect on these variables. There was a statistically significant reduction in postexercise systolic BP in both groups (p = 0.040), without significant change in resting BP along RT (p = 0.159). Regarding HRV, it was observed a reduced sympathetic-vagal balance (training interaction vs. group: p = 0.058, ES = -0.83) in HT subjects. Resistance training promotes a significant acute reduction of BP in the HT and NT groups and provides a slight benefit of cardiac autonomic balance in the HT.

Further comments on oral transmission of Chagas' disease in Brazil: epidemiology, geographical distribution and viability of the infective parasite.

In 2006, Brazilian government received the international certificate of interruption of the vectorial transmission of Chagas' disease. However, outbreaks reported in Brazilian Amazon rainforest bear a regular occurrence and represents a relevant regional epidemiological gauge. The wild life cycle of the Chagas' disease transmission (i.e., triatomine-marsupial cycle) is present outside the previously reported endemic belt, ubiquitously, as infective triatomines can be demonstrated in Palm trees widespread all over the Amazon rainforest. As humans invade the rainforest, one is incidentally caught up and further becomes' an active part of American trypanosomiasis wild life cycle.

Ionic mechanisms and vectorial model of early repolarization pattern in the surface electrocardiogram of the athlete.

BACKGROUND: The electrocardiogram (ECG) of the athlete displays particular characteristics as a consequence of both electrophysiological and autonomic remodeling of the heart that follows continued physical training. However, doubts persist on how these changes directly interact during ventricular activation and repolarization ultimately affecting surface ECG waveforms in athletes. OBJECTIVE: This article considers an in deep rationale for the electrocardiographic pattern known as early repolarization based on both electrophysiological mechanisms at cellular level and the vectorial theory of the cardiac activation. METHODS: The mechanism by which the autonomic remodeling influences the cardiac electrical activation is reviewed and an insight model of the ventricular repolarization based on ionic models and the vectorial theory of the cardiac activation is proposed. RESULTS: Considering the underlying processes related to ventricular electrical remodeling, we propose that, in athletes' heart: 1) vagal modulation increases regional electrophysiological differences in action potential phases 1 and 2 amplitudes, thus enhancing a voltage gradient between epicardial and endocardial fibers; 2) this gradient affects depolarization and repolarization timing sequences; 3) repolarization wave front starts earlier on ventricular wall and partially overcomes the end of depolarization causing an upward displacement of the J-point, ST segment elevation, and inscription of magnified T-waves amplitudes leading to characteristic surface ECG waveform patterns. CONCLUSIONS: In athletes, the association between epicardial to endocardial electrophysiological differences and early repolarization ECG pattern can be demonstrated by the vectorial theory of the ventricular activation and repolarization.

Detection of incipient left ventricular hypertrophy in mild to moderate arterial hypertension with normal electrocardiogram and echocardiogram: a new use for signal-averaged electrocardiography.

OBJECTIVE: To assess signal-averaged electrocardiogram (SAECG) for diagnosing incipient left ventricular hypertrophy (LVH). METHODS: A study with 115 individuals was carried out. The individuals were divided as follows: GI - 38 healthy individuals; GII - 47 individuals with mild to moderate hypertension and normal findings on echocardiogram and ECG; and GIII - 30 individuals with hypertension and documented LVH. The magnitude vector of the SAECG was analyzed with the high-pass cutoff frequency of 40 Hz through the bidirectional four-pole Butterworth high-pass digital filter. The mean quadratic root of the total QRS voltage (RMST) and the two-dimensional integral of the QRS area of the spectro-temporal map were analyzed between 0 and 30 Hz for the frequency domain (Int FD), and between 40 and 250 Hz for the time domain (Int TD). The electrocardiographic criterion for LVH was based on the Cornell Product. Left ventricular mass was calculated with the Devereux formula. RESULTS: All parameters analyzed increased from GI to GIII, except for Int FD (GII vs GIII) and RMST log (GII vs GIII). Int TD showed greater accuracy for detecting LVH with an appropriate cutoff > 8 (sensitivity of 55%, specificity of 81%). Positive values (> 8) were found in 56.5% of the G II patients and in 18.4% of the GI patients (p< 0.0005). CONCLUSION: SAECG can be used in the early diagnosis of LVH in hypertensive patients with normal ECG and echocardiogram.