Ambulatory ECG recording during competitive parachute jumping in apparently healthy young men: more evidence for intermittent vagal dominance during enhanced sympathetic activity.
Using two-channel 24-hour ambulatory ECG recording we studied seven healthy young men during one day of parachute jumping competition (day 1), as compared to one control day (day 2). A symptom limited exercise test was also performed on day 2. Maximal heart rates attained during exercise testing were of the same order as during parachute jumping. In the phases just prior to 'exit', short periods of striking sinus arrhythmia with slow atrial rhythm were present in 3 subjects. Only one of these had slow atrial rhythm during the control day. Atrial and ventricular premature complexes, when present, disappeared with higher heart rates under all circumstances. No AV conduction disturbances were found.
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D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology; D001359:Aviation; D004562:Electrocardiography; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D008297:Male; D013312:Stress, Physiological / Q000150:complications