Electrocardiograms of healthy men after strenuous exercise.

Between August 1954 and May 1957, 682 R.A.F. officers and men volunteered for a study of the electrocardiogram after exercise. Of these, 660 were selected because they had no symptoms, no clinical or radiological evidence of heart disease, a diastolic blood pressure of below 100 mm. Hg, and a normal 12-lead electrocardiogram taken at rest. Certain minor electrocardiographic changes that are believed to have a good prognosis when unaccompanied by other evidence of heart disease (Packard et al., 1954; Manning, 1954) did not disqualify. The frequency of these changes was as follows:-Wolff-Parkinson-White syndrome (1), complete right bundle-branch block (2), incomplete right bundle-branch block (33), P-R of 0-2 to 0-23 sec, (11), and left axis deviation (10). In addition, slurring of R in lead I was present in 5 and minor anomalies of the T wave in 25. Four hundred and fifteen of the men were officers and 245 airmen. Their ages ranged from 19 to 54 years (mean 37T2±5 6 years). A preliminary account of the first 540 cases has been published (Acheson, 1957) and a follow-up study is in progress.