HR max test and fresh perspectives

Of late I thought my training might benefit from the incorporation of heart rate training. I hope that brining this into my training will help me train at the correct intensity and complementarily develop both my aerobic and anaerobic systems. So first things first, I would need to determine my maximum heart rate. There are numerous ways of doing this, some involving scientists and a treadmill. I went for one I found on the Marius Bakken website. My HR max 'target' was 190. Following a fifteen minute warm up I embarked on the first of five one minute intervals. Every minute for the next three minutes I aimed to increase my HR by ten bpm, reaching 180 at the end of the fourth minute. It was getting really tough now. The final minute is an all out effort to get the HR as high as you can. I maxed at 185. This seemed a bit low, considering that last year I saw 190 at the end of 5k; so, I went out in the afternoon and did the 'Hadd' HR test. This involves a good warm up, followed by 800m all out, a two minute recovery and 400m all out. This elicited a max HR of 183. I am unsure how advisable it is to two HR max tests in a day and whether it affects the results of any subsequent effort. One thing is certain- I do not fancy doing one again any time soon. Running until you think you will black out is not pleasant. So, 185 it is. I subsequently read that as your aerobic fitness improves it is more difficult to reach your true max HR and that if your fitness declines you will reach a higher HR quicker, and of course be moving at a significantly slower pace. The first real workout with this approach rook place last Thursday, a twelve mile run, with seven at tempo effort. The average pace for these miles was 06:43 and average HR of 163 or 88% max HR. I was happy enough with this pace considering the >90% humidity and 24C/74F temperatures. Interestingly, before the summer I would have considered 163bpm as only slightly greater effort than marathon pace - if even. However, these tempo miles definitely felt like half Marathon pace. I am a little hopeful that if the environmental conditions were better my splits could be twenty to twenty-five seconds faster. If this is correct, a big if, then it suggests that either I was overtraining in the past, or I am in significantly better shape than I was before the summer. If it's incorrect, then I am in poor shape. In short, I have no idea what kind if shape I am in, but the point of the move to HR training is to receive more objective feedback on my training and prevent either under or overtraining. If nothing else it will bring fresh perspectives to training.