RATE OF COMPRESSION

The AHA sets the optimal rate at 100 compressions per minute. This is equal to a duration of a single compression of 0.6 seconds. The duration of each compression is the length of time from the start of one compression to the start of the next compression. In keeping with the guidelines we allow a variation either side of this figure so that durations from 0.5 - 0.7 seconds are reported as being correct. 

Optimal rate assures the best possible blood flow and tissue oxygenation.  As the rate falls below 100/minute forward blood flow slows. As the rate increases beyond 100/minute, rescuer fatigue increases. This increases other errors, such as slower rate and incomplete chest recoil. Research suggests that a bit too fast is better than a bit too slow.

Establish a rhythm. Some people count; some people establish their own internal rhythm; some people follow an external prompt.

SmartMan© samples the rate 100 times each second. Results report the rate of compressions grouped by times.

The majority of people perform compressions a bit too fast.
A group of people has a problem with being too slow.
Greater variations in rate arise the longer you perform compressions due to fatigue.