Abstract
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.
Key word
sympathetic nerve activity - muscle blood flow - acute exercise
