Alaric

Not quite true. You are correct about the sino-atrial node having a major role: it's a collection of cells that can create a rhythmical pacemaker potential spontaneously, and is a big influence on the heartrate. However, the CNS does also have a huge role in regulating the heart rate, through both parasympathetic (vagus) nerves and sympathetic (from the sympathetic trunk) nerves. The vagus nerve acts on the SA node, releasing a neurotransmitter (acetylcholine) that slows the generation of action potentials by the node, overall slowing the heartbeat. (Side note: atropine, a drug given sometimes during a cardiac arrest, blocks these neurotransmitters from binding the heart cells, thereby preventing the Vagus nerve from slowing the heartrate.) The sympathetic nerves coming from T2-T4 of the spine are more diffuse in their effect, hitting the entire heart and releasing the neurotransmitter norepinephrine. It can increase the heartrate, force of contraction and speed of electrical conduction within the heart. (This is why beta-blockers can be used to slow down the heartrate, by preventing norepinephrine from binding to the heart.)

Thanks for the warm welcome guys, appreciate it!

Hey everyone, I'm a 23 year old student studying medicine at the moment. My background is about 6 years Tang Soo Do, 3 years BJJ, 2 years Muay Thai and a smattering of boxing I picked up from sparring with friends who trained in it. I'm a bit out of practice following a back injury 4 years ago, but am finally getting back into it once more. Starting training in BJJ and MMA very soon. Outside of that, very interested in music, have a passing interest in weightlifting, and have started running: a 10k run is looming at the start of May. Take care, Alaric

It's more common in kids, but still possible in adults. "28% of the cases were aged over 18 years, with the oldest reported in a 44-year-old woman."-http://www.medscape.com/viewarticle/555448_3 Agreed.

Agreed. There's also another thing that may be of interest, which used to be used a lot by medics duing cardiac arrest, called the 'precordial thump.' http://en.wikipedia.org/wiki/Precordial_thump In this they basially used a hammerfist to the sternum, but done in a very specific way so as to minimise injury. The concussion can cause a small amount of depolarisation that can restore sinus rhythm, if you're very lucky. Long story short, trama to the chest can cause changes in heart activity. Of course, this is rare. Look at all the boxers or MMA guys who trade blows to the mediastinum and walk away fine. I don't think that anyone can argue that someone like Tyson or Rutten can't generate more power than the guy showing 'dim mak' in Fight Science. And there is no particular technique, the entire phenomenon is predicated simply on hitting the right place (mediastinum) at the right time (ventricular repolarisation/T-wave). So it's possible to stop/start the heart with blows, but very difficult and exceedingly rare. Plus, the element of chance involved (Hitting at just the right time in the cardiac cycle) makes it untenable as an actual technique.

Chi and chi knockouts are areas that interest me immensely. I'll confess to being a skeptic, not just of 'no-touch' knockouts, but of the whole concept of chi. I'm hoping to get the 'Truth about Chi' thread going again, so if you guys want to discuss it there, it'd probably be best. As regards the chi knockouts, here's an fun video you may have seen before. Long story short: a kiai master who demonstrates his powers upon a mob of his hapless students accepts a challenge from a MMA fighter, and gets pwned. Hardly conclusive evidence that no-touch knockouts don't exist, but a worthwhile reminder that there's lots of charlatans out there in it for the money and renown.

Well this area interests me greatly, so maybe a bit of minor thread necromancy is in order. The major difficulty I have with chi/qi is getting a solid definition of what it actually is. It's generally very diffuse, with as many interpretations as there are people. If you believe Wikipedia (and you shouldn't) the closest interpretation of qi is 'energy'. People above me have mentioned this plenty, in addition to 'aura' and 'life force'. It's apparently a form of energy that we all have, and can be channeled and tapped into to grant boons to the user. Some are pretty simple and plausible, like increased focus and concentration. Others not so much, like 'levitation', 'iron skin' and 'no-touch knockouts.' I'm a reductionist. I like to figure things out by breaking them down into smaller pieces. Before I start, I'd like anyone who's intersted to point out anything wrong with what I've written so far, or maybe offer alternative interpretations.