Vagal modulation of heart rate during exercise: effects of age and physical fitness

• Published in: American journal of physiology. Heart and circulatory physiology 1998-02, Vol.274 (2), p.H424-H429
• Main Authors: Tulppo, Mikko P, Makikallio, Timo H, Seppanen, Tapio, Laukkanen, Raija T, Huikuri, Heikki V
• Format: Article
• Language: English
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.1998.274.2.h424

1  Department of Medicine, Division of Cardiology, University of Oulu, 90220 Oulu; and 2  Merikoski Rehabilitation and Research Center, 90100 Oulu, Finland This study was designed to assess the effects of age and physical fitness on vagal modulation of heart rate (HR) during exercise by analyzing the instantaneous R-R interval variability from Poincaré plots (SD1) at rest and at different phases of a bicycle exercise test in a population of healthy males. SD1 normalized for the average R-R interval (SD1 n ), a measure of vagal activity, was compared at rest and during exercise among subjects of ages 24-34 (young, n  = 25), 35-46 (middle-aged, n  = 30), and 47-64 yr (old, n  = 25) matched for peak O 2 consumption ( O 2 peak ) and among subjects with O 2 peak of 28-37 (poor, n  = 25), 38-45 (average, n  = 36), and 46-60 ml · kg 1 · min 1 (good, n  = 25) matched for age. SD1 n was higher at rest in the young subjects than in the middle-aged or old subjects (39 ± 14, 27 ± 16, and 21 ± 8, respectively; P