O objectivo do presente estudo foi avaliar o comportamento da força muscular e a participação dos indicadores de hipertrofia, nos ganhos de força após 32 semanas de treinamento com pesos (TP), prescrito por zona alvo de repetições máximas, em mulheres na pós-menopausa. Participaram desta pesquisa 14 mulheres saudáveis e não ativas fisicamente. O TP teve frequência semanal de três vezes, em dias alternados. A composição corporal foi mensurada pela técnica das dobras cutâneas. Os indicadores de hipertrofia foram representados pela massa magra total e regional: área muscular do braço (AMB) e coxa (AMC). A força muscular foi avaliada pelo teste de uma repetição máxima nos exercícios leg press horizontal e rosca direta. Para análise estatística foi utilizado o teste de Friedman. Os resultados mostraram que a força muscular apresentou aumentos graduais e significantes durante a intervenção, que houve aumento da AMB e não houve diferença nos valores de AMC. A rosca direta mostrou forte associação com a AMB durante todos os momentos do estudo. Já o leg press pareceu estar mais efetivamente associado ao componente neural de ganhos de força, visto que a AMC não apresentou modificações significantes. Após 32 semanas de TP a força muscular aumentou significantemente, independentemente dos ganhos de massa magra.

The aim of the present study was to evaluate muscle strength and hypertrophy indicators on increases of strength after 32 weeks of resistance training (RT), prescribed by the target of maximum repetitions in postmenopausal women. Fourteen physically inactive healthy women participated in this study. Three times a week they participated on RT. Body composition was measured by the technique of skinfold thickness. The hypertrophy indicators were represented by total and regional lean mass: arm muscle area (AMA) and thigh muscle area (TMA). Muscle strength was assessed through the test of one maximum repetition in exercises of horizontal leg press and arm curl. Statistical analysis was performed using the Friedman test. Results showed increases in muscle strength, AMA but not in TMA. Arm curl was strongly correlated to AMA. Leg press seemed to be associated to neural components of increases in strength. Muscle strength significantly increased after 32 weeks of RT regardless of increases in lean mass.

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.

The purpose of the present study was to evaluate the effects of aerobic physical training (APT) on heart rate variability (HRV) and cardiorespiratory responses at peak condition and ventilatory anaerobic threshold. Ten young (Y: median = 21 years) and seven middle-aged (MA = 53 years) healthy sedentary men were studied. Dynamic exercise tests were performed on a cycloergometer using a continuous ramp protocol (12 to 20 W/min) until exhaustion. A dynamic 24-h electrocardiogram was analyzed by time (TD) (standard deviation of mean R-R intervals) and frequency domain (FD) methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF) frequencies and as the LF/HF ratio. Control (C) condition: HRV in TD (Y: 108, MA: 96 ms; P<0.05) and FD - LFa, HFa - was significantly higher in young (1030; 2589 ms²/Hz) than in middle-aged men (357; 342 ms²/Hz) only during sleep (P<0.05); post-training effects: resting bradycardia (P<0.05) in the awake condition in both groups; VO2 increased for both groups at anaerobic threshold (P<0.05), and at peak condition only in young men; HRV in TD and FD (a and nu) was not significantly changed by training in either groups. The vagal predominance during sleep is reduced with aging. The resting bradycardia induced by short-term APT in both age groups suggests that this adaptation is much more related to intrinsic alterations in sinus node than in efferent vagal-sympathetic modulation. Furthermore, the greater alterations in VO2 than in HRV may be related to short-term APT.

We investigated the effects of aerobic training on the efferent autonomic control of heart rate (HR) during dynamic exercise in middle-aged men, eight of whom underwent exercise training (T) while the other seven continued their sedentary (S) life style. The training was conducted over 10 months (three 1-h sessions/week on a field track at 70-85% of the peak HR). The contribution of sympathetic and parasympathetic exercise tachycardia was determined in terms of differences in the time constant effects on the HR response obtained using a discontinuous protocol (4-min tests at 25, 50, 100 and 125 watts on a cycle ergometer), and a continuous protocol (25 watts/min until exhaustion) allowed the quantification of the parameters (anaerobic threshold, VO2 AT; peak O2 uptake, VO2 peak; power peak) that reflect oxygen transport. The results obtained for the S and the T groups were: 1) a smaller resting HR in T (66 beats/min) when compared to S (84 beats/min); 2) during exercise, a small increase in the fast tachycardia (<FONT FACE="Symbol">D</font>0-10 s) related to vagal withdrawal (P<0.05, only at 25 watts) was observed in T at all powers; at middle and higher powers a significant decrease (P<0.05 at 50, 100 and 125 watts) in the slow tachycardia (<FONT FACE="Symbol">D</font>1-4 min) related to a sympathetic-dependent mechanism was observed in T; 3) the VO2 AT (S = 1.06 and T = 1.33 l/min) and VO2 peak (S = 1.97 and T = 2.47 l/min) were higher in T (P<0.05). These results demonstrate that aerobic training can induce significant physiological adaptations in middle-aged men, mainly expressed as a decrease in the sympathetic effects on heart rate associated with an increase in oxygen transport during dynamic exercise.