The fast pace of a heart. Normally, a heart pace of an adult should be about 60 or 100 beats per minute. If a person has a faster pulse when having a rest, it is called tachycardia. The pace, in this case, can be either slower or faster from time to time. In other words, the heartbeat can fluctuate in a low diapason, high diapason or both simultaneously. Thus, the heart works in a different way when the person is stressed or has an infection. It all has a very simple explanation – our heart is trying to activate our immune system to make the oxygen circulate in blood faster by the mean of blood pumping increase. The heart tries to speed up body recovery process.