Heart Rate and a zero reading

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Just a quick question before I leave for work :)

Sometimes while working out I will glance at my heart rate monitor and it will shoe 00 does this affect mt average HR for the duration on my workout? I have an older model polar (B3) so far it has been pretty consistant with my average rate (I then plug my number on a different site to gte my caloric burn) mostly I am just curious,

Thanks Everyone!
~Winter