Effect of moderate physical exercise on noninvasive cardiac autonomic tests in healthy volunteers

Background: In addition to the assessment of extreme cardiovascular reserve , new methodology is needed which is sensitive enough to detect subtle impr ovement in cardiovascular fitness in cardiac patients. Aim: This study mode lled subtle clinical improvement by a moderate physical activity programme in healthy volunteers and investigated whether the improved fitness is dete ctable by non-invasive tests of cardiac autonomic status. Methods: Twenty h ealthy volunteers (ten women, mean age 39.6+/-7.8 years) were divided into two groups of five women and five men in each. One group (the active group) was subjected to a moderate physical training programme for 6 months. The other group (the passive group) served as controls and continued with a pre dominantly sedentary Lifestyle. Twice before commencing the exercise progra mme and regularly afterwards, subjects were investigated by a series of non -invasive autonomic tests including controlled respiration, active postural change, isometric handgrip, and Valsalva manoeuvre. A continuous three lea d semi-orthogonal electrocardiogram and continuous blood pressure monitorin g was obtained. Statistical descriptors of heart rate and blood pressure, s pectral descriptors of their modulation, and baroreflex index giving the pr oportion between simultaneous heart rate and blood pressure changes were ob tained from each test. Results: Although the exercise programme was not ext ensive enough to be detected in changes of the baseline heart: rate, the mi nimum RR interval during the Vasalva manoeuvre prolonged significantly with exercise in the active group. The mean arterial diastolic pressure decreas ed significantly. High frequency components of RR interval modulations decr eased in supine controlled respiration and increased in standing controlled respiration and a trend towards an increase of both high frequency and low frequency components of diastolic arterial pressure modulations was noted with exercise. Baroreflex index assessed from Vasalva manoeuvre increased s ignificantly. Conclusion: The study suggests that a selected set of non-inv asive autonomic tests is sensitive enough to depict moderate improvement in cardiovascular fitness and that a multivariate assessment of cardiovascula r fitness based on these tests might be applicable to monitoring chronic ca rdiac patients subjected to different clinical management modes. (C) 1999 E lsevier Science ireland Ltd. All rights reserved.