Changes in systolic and diastolic time intervals during prolonged exercise. (Part 3).
- VernacularTitle:長時間運動中に起こる心周期分画の変動 （第３報）
- Author:
YOSHIHARU NABEKURA
;
TAKESHI NISHIYASU
;
SACHIKO HONMA
;
HARUO IKEGAMI
- Publication Type:Journal Article
- Keywords:
prolonged exercise;
systolic time intervals;
diastolic time;
stroke volume;
blood pressure
- From:Japanese Journal of Physical Fitness and Sports Medicine
1990;39(5):350-359
- CountryJapan
- Language:Japanese
-
Abstract:
A study was undertaken to elucidate the mechanism responsible for the specific changes in systolic time intervals (STIs), diastolic time (DT) and the ratio of total electromechanical systole to DT (QS2/DT), which were observed during prolonged exercise17, 19) Sixteen healthy male students performed short-term incremental maximal exercise and 40-min submaximal exercise with a work load requiring 65% of maximal oxygen consumption on a bicycle ergo-meter, Heart rate (HR), stroke volume (SV), blood pressure (BP), STIs and DT were calculated from electrocardiogram, phonocardiogram, derivative of ear densitogram, impedance cardiogram and finger arterial pressure wave.
1) During the short-term exercise, STIs, DT and QS2/DT changed rectilinearly in accordance with increased HR, whereas they changed in a specific zigzag pattern during the prolonged exercise.
2) During the prolonged exercise, SV and BP were lower than those during the short-term exercise, except for SV between 1 and 2 min after the start of the exercise. From 2 min onwards, left ventricular ejection time (LVET), QS2 and QS2/DT became smaller than those during the short-term exercise.
3) Differences between the measured values of LVET, pre-ejection period (PEP) and PEP/LVET and those predicted by multiple regression equations during the prolonged exercise were smaller than those during the short-term exercise.
From these findings, it was concluded that the specific changes observed in STIs, DT and QS2/DT during prolonged exercise are produced by decrease of SV and BP in the early stage, and probably influenced by a decrease in myocardial contractility in the late stage.
