Your max heart rate is what it is. You can be very fit and have a high rate or very unfit and have a low rate. It has nothing to do with your fitness, ability or even your love life, its personal to you. Yes it may drop bit by bit as you get older but it does remain very consistent.
The oft used 220 - age is only true for about 80% of the people.
I have hit 182 in runs but the 220 - age says I should be 168. A better formula (about 90% of people fit this) is 205 - half your age which would give you 185 rather than 180.
When you start your run your heart rate can be high for the first part especially if you are unfit, but it tends to steady down when your heart knows what is expected from it.
Your resting rate however can vary wildly depending upon your level of fatigue, health or stress. If you have set your HRM up with this figure I would say measure it over several days. I have gone between 45 and 56 in one week. it can also be a good way to see if you are over doing it or coming down with a cold.