Static Apnea (Breath Holding) Experiments

"How long can I hold my breath?", is the question. Here are my test results:

Attempt 1	55 sec. Got panicky and was surprised how short it was.
Attempt 2	2 min. Spend time relaxing and deep breathing before.
Attempt 3	2:30 min. Did some internet research on techniques
Attempt 4	3:36 min. No alcohol for a week, a day’s rest since excessing. It was an extremely intense and somewhat unpleasant experience. My fingers started tingling at about 3 min. By the end my fore arms where numb and aching.
Attempt 5	3:54 min. Final breath hold after completing CO2 and O2 tables http://goo.gl/tG3Yl

Room to improve? Certainly, I mean, experienced freedivers go for 5 to 8 min. It seems a bit daunting though. As far as I understand I need to do:

1. Meditate before starting and get heart rate down to at least 60 bpm before starting. In my last attempt I started at 80 bpm which is quite high, and dropped to 40 by the end of the 3:36 min.
2. Do dynamic apnea training. Swimming  drills while holding my breath. e.g. Underwater lengths, freestyle breathing every 9th stroke. 5 dolphin kick per 1 breast stroke breath.
3. Static apnea exercises. http://goo.gl/tG3Yl
4. Strengthen diaphragm to enable greater long volume.
5. Learn to pack - a technique for swallowing additional air into the lungs.
6. Go on a freediving course.

Related: About freediving