Effect of long-duration isometric muscle contractions on the R spike peripheral pulse wave time interval
Rehfeldt, H.; Kramer, H.; Schröder, R.
Zeitschrift für die Gesamte Hygiene und ihre Grenzgebiete 33(11): 595-597
1987
ISSN/ISBN: 0049-8610 PMID: 3439238 Document Number: 301812
Due to methodical difficulties in non-invasive blood pressure measurement in field investigations the work-induced cardiovascular reactions are often described by considering only the heart rate. In order to get additional information about vascular activity, the interval between R-wave and consecutive pulse wave was derived during sustained isometric contractions together with blood pressure and heart rate. There were no marked changes in heart rate throughout the 15 min handgrip contractions at 13% MVC despite increasing blood pressure and increasing EMG activity. The ECG-pulse delay decreased significantly in course of the contraction period and returned to rest values within 5 min after the end of the contractions. These results lead to the conclusion that the load-induced cardiovascular responses in sustained isometric contractions cannot be described sufficiently by considering only the heart rate and that the ECG-pulse interval continuously picked up throughout the work providing additional important information.