Heart Rate Readings - Too High

I have now completed around four or five 10K training runs in around the 44 or 45 minute mark.  The one thing I have noticed is that my heart rate reading is averaging around 152 bpm.  Prior to injury I was covering that distance in roughly the same time, but with at least 10 beats per minute lower i.e. 142 bpm.  I remembered it took a while to steady my heart rate the last time I was out injured.  This tells me I am nowhere near ready too return to racing.  My aim for 2012 is to curtail my races to around twelve or so.  One a month seems reasonable and hopefully this will avoid the lengthy injuries I've incurred over these last three years.