Yes since your heart rate fluctuates based upon your activity level. Resting heart rate varies greatly from your active heart rate. The P wave and the QRS complex represent depolarization of the atrial and ventricular muscle respectively. Why does the QRS complex have the larger amplitude? The QRS complex correlates with the action needed to push blood back out away from the heart that requires higher pressure. Heart rate was calculated based upon the peak-to-peak interval of the R waves.