The purpose of this study was to develop a compact portable ECG recorder for sports medicine and to evaluate ECG findings during various types of competitive sports with the recorder.
　The recorder with a microcomputer was down sized (124×70×22 mn, 200g) and easy to record ECGs at highly dynamic exercise.
　ECGs were recorded for 10 ~ 15 min during various types of competitive sports from 94 students and 99 apparently healthy middle aged subjects. Sports were classified into highly dynamic and highly static, highly dynamic, and highly static types.
　Incidence of arrhythmia was greater than 50% in kendo, running (sprint), fencing and tennis for students, and in kendo, naginata, running, ping-pong, judo and weight traning for middle aged subjects. The most common arrhythmia was supraventricular premature beat (students 36%, middle aged 37%) and the next was ventricular premature beat (students 9%, middle aged 24%).
　Incidence of arrhythmia was greater in middle aged subjects than in students for ventricular premature beats (middle aged 24%, students 9%) and runs of sapraventricular premature beats (middle aged 7%, students 1%).
　Greater incidence of runs of supraventricular premature beats was observed in highly dynamic and static (7%) and highly static (8%) sports compared with highly dynamic (1%) sports.

DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE