A Ballistocardiographic study of healthy young adult males.

Ballistocardiograms were obtained from 319 well-screened young soldiers on an electrically equalized electromagnetic ballistocardiograph. The records were analyzed for the basic pattern and for variations. The conventional criteria of normal were confirmed. The most frequently observed variation consisted of changes in complexes written during expiration which, when of sufficient degree, resemble those described as abnormal. Prominent L waves were also common. Variations of the J and K waves were rare. A grade 1 or 2 abnormality was noted on 22 records, but when respiration was suspended, only three remaiined questionably abnormal.