100% more than your resting heart rate? Where did you get this info from? If that were the case, my RHR is at 42bpm, I'd only be working at 84 bpm!
67 BPM for a resting heart rate is just below the average male, however it is elevated for someone involved in fitness. HIIT will bring it down significantly. The idea behind HIIT is to exercise in intervals to your max. So you would be looking at eventually getting your heart rate way up - around 180-190+ bpm (having a max at 201 for your age). The harder you push the more benefits you are going to obtain from this style of cardio by demanding more from your anaeobic system.
Bare in mind though that you shouldn't go all out right from the get go. If you've never trained to your max before, start off with a medium-high intensity and gradually become more and more intense. This is so it's not a complete shock to your system and you don't end up in the bathroom for half an hour on your first attempt. Also, ensure that you are in sound medical condition before attempting this style of cardio.
I used to suffer from asthma and the first time I attempted HIIT I suffered a mild attack because I pushed too hard. Whilst it only lasted for about 30 seconds, it was pretty intense. After that, I gradually increased the intensity. Now my fitness levels have gone through the roof the asthma has completely dissapeared - I push to my max every single time - very big health benefits associated with this style of cardio
