Post-Exercise Neurovascular Control in Chronic Heart Failure Patients.

It remains unknown whether or not a reduction in muscle sympathetic nerve activity in heart failure patients is associated over time with the effects of long- or short-term repeated exercise. 10 chronic heart failure patients, age 49±3 years old, functional class I-III NYHA, ejection fraction <40% were randomly submitted to either an acute bout of moderate continuous exercise OR high-intensity interval exercise. Muscle sympathetic nerve activity (microneurography) and forearm blood flow (venous occlusion plethysmography) were evaluated pre- and post-exercise sessions. The moderate exercise consisted of cycle exercise at an intensity corresponding to anaerobic threshold. The interval exercise consisted of a 2-min cycle exercise at intensity corresponding to anaerobic threshold, followed by a 1-min exercise set at respiratory compensation point. Exercise capacity was evaluated by cardiopulmonary exercise test. The caloric expenditure in both sessions was 100 kcal. Baseline muscle sympathetic nerve activity and forearm blood flow levels were not different between sessions. Moderate or high-intensity exercise caused no significant changes in muscle sympathetic nerve activity and forearm blood flow. These findings suggest that the reduction in muscle sympathetic nerve activity and the increase in forearm blood flow provoked by exercise training in chronic heart failure patients are due to cumulative effects over time.

High levels of C-reactive protein are associated with reduced vagal modulation and low physical activity in young adults.

The purpose of this study was to examine the relationship between cardiac autonomic control derived from heart rate variability (HRV), high-sensitivity C-reactive protein (hs-CRP) and physical activity (PA) levels measured using accelerometers. A total of 80 healthy university students volunteered to participate in this study (20.56 ± 0.82 years, 1.36 ± 1.5 mg/L of hs-CRP). The participants were divided into groups based on tertiles of hs-CRP. Analysis of covariance adjusted to PA was used to assess group differences in HRV. Associations between hs-CRP, HRV indices and PA were analyzed using Pearson's correlation. The participants at the highest tertile of hs-CRP (tertile 3) had lower cardiac vagal modulation (SDNN, tertile 1=78.05 ± 5.9,tertile 2=82.43 ± 5.9,tertile 3=56.03 ± 6.1; SD1, tertile 1=61.27 ± 5.3, tertile 2=62.93 ± 5.4, tertile 3=40.03 ± 5.5). In addition, vagal indices were inversely correlated with hs-CRP but positively correlated with PA (SDNN r=-0.320, SD1 r=-0.377; SDNN r=0.304, SD1 r=0.299; P<0.05). Furthermore, the most physically active subjects had lower levels of hs-CRP and the highest levels of vagal modulation.