Electrocardiography, Dr. D. Penney




Table 19. DETERMINATION OF HEART RATE
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The comparison of two ECG strips; one a sedentary 35 yr.-old vs. a 23 yr.-old long distance runner. [paper speed is standard (25 mm/sec.); large horizontal squares 0.2 sec.; small squares 0.04 sec.)

Method 1:

Measure R-R interval -

HR = ( 60 sec./min ) / ( R-R sec. / cycle )

For sedentary: ( 60 sec./min. ) / ( 0.75 sec. / cycle ) = 80 cycles/min

vs. runner = 44 cycles/min.

Note: ECG strip has 1 mV calibration signal superimposed, giving 2 squares, or 1 cm deflection. __________________________________________________________________________________



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