Missed my Long Run

Christmas finally took it's toll and I finished off last year and started this year with a forced rest day caused by flu like symptoms.  I wasn't feeling too good on Friday and almost couldn't be arsed going for a run and when waking on Saturday morning my waking heart rate was almost 20 beats higher than usual so I knew something was a brewing.  With a long train journey ahead of me I decided not to run my planned hilly 30K and consoled myself with the thoughts of a quiet 30K on New Years Day around North Kerry to start 2012.
I took it relatively easy on Saturday (NYE) and drank very little but on waking the following morning my heart rate was still elevated.  Still tempted to go out for even a shorter run I knew it best to put the effort into recovering as it's at times like this that you are liable to 'overtraining'.  Overtraining is caused by doing more than your body is capable of doing and it's easier to bounce back from a flu than it is to bounce back from overtraining.
Today Monday my heart rate was still slightly elevated but lower than the previous 2 days so I decided to go for an easy run and just to be on the safe side I ran it in my recovery zone and even at that it still felt like quite an effort.
When your heart rate is elevated at rest it takes less effort to get into your training zone and if you measure your run by pace you may be pushing your body more than it can handle by trying to stick with your usual pace.  It's this increased intensity that can lead to overtraining.
Your heart rate can tell you a lot if you learn how to listen.  With regular monitoring you will begin to notice a trend and it's variations in this trend that will tell you what you need to know.