K Imai, H Sato, M Hori, H Kusuoka, H Ozaki, H Yokoyama, H Takeda, M Inoue, T Kamada
OBJECTIVES: Vagally mediated heart rate recovery after exercise was assessed in patients with chronic heart failure and in well trained athletes by analyzing the postexercise heart rate decay. BACKGROUND: Vagal reactivation is an important cardiac deceleration mechanism after exercise. However, alterations of this mechanism under pathologic conditions have not been characterized because of the lack of a specific index. METHODS: To find a vagally mediated component of heart rate recovery, the time constants of the beat-by-beat heart rate decay for the first 30 s (T30) and the first 120 s (T120) after exercise were obtained at six levels of exercise in eight normal volunteers: 1) at maximal exercise, 2) at anaerobic threshold, 3) at anaerobic threshold with propranolol administration, 4) at anaerobic threshold with atropine administration, 5) at anaerobic threshold with concomitant administration of both drugs, and 6) at 50% of anaerobic threshold...
November 15, 1994: Journal of the American College of Cardiology