Exercise intensity optimization for men with high cardiorespiratory fitness.

Exercise intensity is a key parameter for exercise prescription but the optimal range for individuals with high cardiorespiratory fitness is unknown. The aims of this study were (1) to determine optimal heart rate ranges for men with high cardiorespiratory fitness based on percentages of maximal oxygen consumption (%VO(2max)) and reserve oxygen consumption (%VO(2reserve)) corresponding to the ventilatory threshold and respiratory compensation point, and (2) to verify the effect of advancing age on the exercise intensities. Maximal cardiorespiratory testing was performed on 210 trained men. Linear regression equations were calculated using paired data points between percentage of maximal heart rate (%HR(max)) and %VO(2max) and between percentage of heart rate reserve (%HRR) and %VO(2reserve) attained at each minute during the test. Values of %VO(2max) and %VO(2reserve) at the ventilatory threshold and respiratory compensation point were used to calculate the corresponding values of %HR(max) and %HRR, respectively. The ranges of exercise intensity in relation to the ventilatory threshold and respiratory compensation point were achieved at 78-93% of HR(max) and 70-93% of HRR, respectively. Although absolute heart rate decreased with advancing age, there were no age-related differences in %HR(max) and %HRR at the ventilatory thresholds. Thus, in men with high cardiorespiratory fitness, the ranges of exercise intensity based on %HR(max) and %HRR regarding ventilatory threshold were 78-93% and 70-93% respectively, and were not influenced by advancing age.

Abnormal muscle metaboreflex control of sympathetic activity in never-treated hypertensive subjects.

BACKGROUND: Muscle metaboreflex control in hypertensive subjects has not been described yet. We investigated the integrity of muscle metaboreflex control of muscle sympathetic nerve activity (MSNA) and blood pressure (BP) in never-treated hypertensive subjects. METHODS: Eighteen hypertensive (42+/-1 years) and 22 normotensive subjects (38+/-1 years) were studied. The MSNA was measured by microneurography and forearm blood flow (FBF) by venous occlusion plethysmography. The BP was noninvasively monitored. RESULTS: Baseline MSNA was significantly increased in hypertensive subjects when compared with normal subjects (34+/-2 v 22+/-2 bursts/min, P<.001). Baseline FBF was significantly decreased in hypertensive subjects (2.66+/-0.2 v 2.05+/-0.1 mL/min/100 mL, P=.04). During moderate handgrip exercise (30% maximal voluntary contraction), MSNA levels were significantly higher in hypertensive subjects. However, MSNA responses were significantly lower in hypertensive subjects (1+/-3 v 10+/-2 bursts/100 heart beats, P = .001). Similarly, FBF responses were significantly lower in hypertensive subjects when compared with normotensive subjects (0.70+/-0.19 v 1.60+/-0.36 mL/min/100 mL, P=.04). During the postexercise circulatory arrest, when the metaboreflex control is isolated, MSNA levels returned toward baseline in hypertensive subjects (58+/-4 v 55+/-3 bursts/100 heart beats, P=.98). In contrast, in normotensive subjects, MSNA levels remained significantly elevated when compared with baseline (48+/-3 v 35+/-1 bursts/100 heart beats, P<.001). CONCLUSIONS: These findings suggest an association between hypertension and decreased muscle metaboreflex control of MSNA.

Effects of home-based exercise training on neurovascular control in patients with heart failure.

BACKGROUND: The effect of home-based exercise training on neurovascular control in heart failure patients is unknown. AIMS: To test the hypothesis that home-based training would maintain the reduction in muscle sympathetic nerve activity (MSNA) and forearm vascular resistance (FVR) acquired after supervised training. METHODS AND RESULTS: Twenty-nine patients (54+/-1.9 years, EF<40%) were randomised into two groups: untrained control (n=12) and exercise trained (n=17). Both groups underwent assessment of Quality of Life (QoL), MSNA, and forearm blood flow. The exercise group underwent a 4-month supervised training program followed by 4 months of home-based training. After the initial 4 months of training, patients in the exercise group showed a significant increase in peak VO(2) and reduction in MSNA, compared to the untrained group, but this was not maintained during 4 months of home-based training. In contrast, the decrease in FVR (56+/-3 vs. 46+/-4 vs. 40+/-2 U, p=0.008) and the improvement in QOL that were achieved during supervised training were maintained during home-based training. CONCLUSIONS: Home-based training following supervised training is a safe strategy to maintain improvements in QoL and reduction in FVR in chronic heart failure patients, but is an inadequate strategy to maintain fitness as estimated by peak VO(2) or reduction in neurohumoral activation.